I have a question that I need help with. I have a set that has desaturated red that I just cant push any farther. its close but not quite there yet. my delta E measures lower when reds value for Y, calculated from the Rec 709 chart, is higher than it is supposed to be. when I try to dial down the value to get it closer to where the correct value is, the delta E gets higher. I thought it would get lower. the color point on the cie diagram stays in the same position. whats going on here. according to delta E it would seem like I should adjust the gain for red up to compensate for its desaturation. is this correct. or should I ignore delta E and get that gain as close as possible. I hope i'm making sense.

I have a question that I need help with. I have a set that has desaturated red that I just cant push any farther. its close but not quite there yet. my delta E measures lower when reds value for Y, calculated from the Rec 709 chart, is higher than it is supposed to be. when I try to dial down the value to get it closer to where the correct value is, the delta E gets higher. I thought it would get lower. the color point on the cie diagram stays in the same position. whats going on here. according to delta E it would seem like I should adjust the gain for red up to compensate for its desaturation. is this correct. or should I ignore delta E and get that gain as close as possible. I hope i'm making sense.This is a complicated subject. The "correct" brightness for a color is an ambiguous target.

First, it can be correct relative to a specified gamut (e.g., Rec. 709) or correct relative to what is expected for a non-standard gamut. Those 2 numbers generally won't be the same. In particular, a non-standard gamut such as you describe with a desaturated red will expect a somewhat brighter red.

Second dE is an ambiguous term. There is not one, but several, dE formulas. Only the 1976 formulas (CIELUV and CIELAB) predict the type of reverse interaction between saturation and brightness you have noticed. Others do not.

This is a complicated subject. The "correct" brightness for a color is an ambiguous target.... First, it can be correct relative to a specified gamut (e.g., Rec. 709) or correct relative to what is expected for a non-standard gamut. Those 2 numbers generally won't be the same. In particular, a non-standard gamut such as you describe with a desaturated red will expect a somewhat brighter red.

Is there some program or spreadsheet out there that recalculates the correct Luma targets (red's level versus white's measurement) to aim for based on your individual set's xy coordinates for the primaries?

My set has fairly oversaturated red and green vs. Rec 709's xy points. So if I am understanding your explanation above, if I adjust red to get 21% of white's measurement, I might be actually off in terms of correct Color setting for my set?

C.

Is there some program or spreadsheet out there that recalculates the correct Luma targets (red's level versus white's measurement) to aim for based on your individual set's xy coordinates for the primaries?

My set has fairly oversaturated red and green vs. Rec 709's xy points. So if I am understanding your explanation above, if I adjust red to get 21% of white's measurement, I might be actually off in terms of correct Color setting for my set?The math for this is published in the Dec. issue of Widescreen Review. I did post a spreadsheet here some time ago, but I don't recall where.

Is there some program or spreadsheet out there that recalculates the correct Luma targets (red's level versus white's measurement) to aim for based on your individual set's xy coordinates for the primaries?

My set has fairly oversaturated red and green vs. Rec 709's xy points. So if I am understanding your explanation above, if I adjust red to get 21% of white's measurement, I might be actually off in terms of correct Color setting for my set?

C.

To answer your first question, C, yes there is. Both CalMAN and Progressive Labs' software package (CA-6X) offer the ability to do custom RGB transforms/color targets based on your set's actual primaries. This is very handy for sets like my old Mits CRT RPTV, which has no ability to adjust primaries. It's especially useful for knowing where the secondaries should be, since they are calculated from the primaries, and you won't be trying to hit secondary targets based on primary values that don't match what you have.

I am calibrationg to the rec709 standard and as far as I was aware the cie 1931 gaumat was what I was using. I am using color hcfr and it is set to rec709. to my understanding and what I see of the cie Diagram, I thought that color hcfr would automatically use cie 1931. if that is the case than it would seem that according to what you have said I should not be seeing the results I am describing. the blue on my set is consistantly desaturated on these sets.(probably an inaccurate color wheel). I have a Mitsubishi wd-65835. I am obviously missing something here. my sensor isn't the best (eyeone lt) but these results are repeatable. any other words of wisdom?

I am calibrationg to the rec709 standard and as far as I was aware the cie 1931 gaumat was what I was using. I am using color hcfr and it is set to rec709. to my understanding and what I see of the cie Diagram, I thought that color hcfr would automatically use cie 1931. if that is the case than it would seem that according to what you have said I should not be seeing the results I am describing. the blue on my set is consistantly desaturated on these sets.(probably an inaccurate color wheel). I have a Mitsubishi wd-65835. I am obviously missing something here. my sensor isn't the best (eyeone lt) but these results are repeatable. any other words of wisdom?

goto accupel.com and click on hdg4000 manual and download the display calculator. punch in the actual x y measurments of your primaries and it will tell you what the Y of your primaries should be and what the x y Y of your secondaries should be based on your primaries x y position.

goto accupel.com and click on hdg4000 manual and download the display calculator. punch in the actual x y measurments of your primaries and it will tell you what the Y of your primaries should be and what the x y Y of your secondaries should be based on your primaries x y position.

http://www.accupel.com/HDG4000_manuals.html

At the bottom is the software. Thanks!

cool little program. it definitely will allow you to experiment but I'm not seeing where it will tell me anything that colorhcfr wouldn't. perhaps I'm not using it right yet. one question, is 50 ire gray the grey the program is expecting?

so we are all going on the assumption that the Y value should be different if the color in question is not the correct saturation for the color gamut. according to how I am understanding this, that isn't the case unless we are using cie 1974 but color hcfr is using cie 1931 and that is what I am using. this, of course still leaves the question of why I am getting bad delta E at close to the correct Y value.

I am calibrationg to the rec709 standard and as far as I was aware the cie 1931 gaumat was what I was using. I am using color hcfr and it is set to rec709. to my understanding and what I see of the cie Diagram, I thought that color hcfr would automatically use cie 1931. if that is the case than it would seem that according to what you have said I should not be seeing the results I am describing. the blue on my set is consistantly desaturated on these sets.(probably an inaccurate color wheel). I have a Mitsubishi wd-65835. I am obviously missing something here. my sensor isn't the best (eyeone lt) but these results are repeatable. any other words of wisdom?I think that you are confusing different gamuts (SMPTE-C vs. Rec. 709, for example) with different color spaces that depict those gamuts (1931 xy vs. 1976 u'v', for example). You can display the Rec. 709 gamut in either of these color spaces, though the 1976 version is more perceptually uniform.

BTW, an undersaturated blue on these displays is not uncommon.

cool little program. it definitely will allow you to experiment but I'm not seeing where it will tell me anything that colorhcfr wouldn't. perhaps I'm not using it right yet. one question, is 50 ire gray the grey the program is expecting?

so we are all going on the assumption that the Y value should be different if the color in question is not the correct saturation for the color gamut. according to how I am understanding this, that isn't the case unless we are using cie 1974 but color hcfr is using cie 1931 and that is what I am using.

No when it says grey it's talking about your white point since "white" is just 100% grey.

http://www.accupel.com/HDG4000_manuals.html

At the bottom is the software. Thanks!

Yow! I forgot about Greg's cool little calculator. Sorry, guys.:o

Yow! I forgot about Greg's cool little calculator. Sorry, guys.:oMe too.

cool little program. it definitely will allow you to experiment but I'm not seeing where it will tell me anything that colorhcfr wouldn't. perhaps I'm not using it right yet. one question, is 50 ire gray the grey the program is expecting?

so we are all going on the assumption that the Y value should be different if the color in question is not the correct saturation for the color gamut. according to how I am understanding this, that isn't the case unless we are using cie 1974 but color hcfr is using cie 1931 and that is what I am using. this, of course still leaves the question of why I am getting bad delta E at close to the correct Y value.

Y is your light output. It in itself doesn't have an effect on Delta E.

Daniel

Y is your light output. It in itself doesn't have an effect on Delta E.That is correct only for gray scale measurements. For pri/sec color the brightness of the color has a profound impact on dE.

Thank you for the clarification :)

That is correct only for gray scale measurements. For pri/sec color the brightness of the color has a profound impact on dE.

dE can be 2-D or 3-D and it "works" for gray or colors - any point within a color space. It is merely an expression of how "far" a measured point is from a reference/target point within any given color space. If the reference point is expressed in 2 dimensions (xy or uv most commonly), dE is only expressing that 2-D difference and L or Y could be way off. If all 3 dimensions are included in the measurement and reference point, dE can be a 3-D expression. A dEuv formula implies that this is only a 2-D calculation, which is not influenced by L or X. On the other hand a dEuvL calculation would require all 3 coordinates (for the target and measurement) and WOULD be influenced by L or X.

We (calibrators) don't typically USE dE with grayscale measurements, but we could if the software being used was setup that way. Before starting, you'd have to enter a Gamma target value along with a reference white measurement so L or Y target values could be calculated for each step in the grayscale. This is all done in the AccuPel Calculator tool and in CalMAN without ever coming out and expressing the actual dE number... you do get a target value for L or Y and it's up to you to adjust Y or L to get as close as possible to the target value. So you use the dE concept without ever seeing the number or how it affects the 2-D dE number you DO see... assuming you are working with something that allows adjusting L or Y for each grayscale step and primary/secondary color, like a Lumagen Radiance XD video processor. What's interesting is that there are more products out there now with 3-D control over primaries (and 2-D control over secondaries) than there are products with 10-step grayscale luminance controls. Most often we get a Gamma setting that may or may not produce the desired end result for step-by-step luminance.

dE can be 2-D or 3-D and it "works" for gray or colors - any point within a color space. It is merely an expression of how "far" a measured point is from a reference/target point within any given color space. If the reference point is expressed in 2 dimensions (xy or uv most commonly), dE is only expressing that 2-D difference and L or Y could be way off. If all 3 dimensions are included in the measurement and reference point, dE can be a 3-D expression. A dEuv formula implies that this is only a 2-D calculation, which is not influenced by L or X. On the other hand a dEuvL calculation would require all 3 coordinates (for the target and measurement) and WOULD be influenced by L or X.

We (calibrators) don't typically USE dE with grayscale measurements, but we could if the software being used was setup that way. Before starting, you'd have to enter a Gamma target value along with a reference white measurement so L or Y target values could be calculated for each step in the grayscale. This is all done in the AccuPel Calculator tool and in CalMAN without ever coming out and expressing the actual dE number... you do get a target value for L or Y and it's up to you to adjust Y or L to get as close as possible to the target value. So you use the dE concept without ever seeing the number or how it affects the 2-D dE number you DO see... assuming you are working with something that allows adjusting L or Y for each grayscale step and primary/secondary color, like a Lumagen Radiance XD video processor. What's interesting is that there are more products out there now with 3-D control over primaries (and 2-D control over secondaries) than there are products with 10-step grayscale luminance controls. Most often we get a Gamma setting that may or may not produce the desired end result for step-by-step luminance.

Doug:

I can't quite tell whether I agree with this or not.

First, you correctly point out that dE can be 2-D or 3-D. Using that terminology, then the correct methodology is to use 2-D measurements with the grayscale and 3-D measurements with pri./sec. colors. There are very good reasons for this which we can discuss further if you like.

Second, having made that distinction, I am not sure what you mean when you write that "We (calibrators) don't typically USE dE with grayscale measurements. . . ." I assume what you meant to say here was we don't typically use 3-D measurements for the grayscale. Again, there are very good reasons for this.

Third, I really don't know what you mean when you write that "Before starting, you'd have to enter a Gamma target value along with a reference white measurement so L or Y target values could be calculated for each step in the grayscale. This is all done in the AccuPel Calculator tool. . . ."

This is NOT how Greg's Display Calibration app handles dE for gray scale measurements. The app has two tabs, one for gray scale and one for color gamut. In the grayscale section, the dE values calculated are strictly 2-D. You can change the target gamma to anything you like and that does not affect the dE calculation, as shown below. In fact, the app allows you the ability to enter the measured Y values in the grayscale section only for the purpose of seeing the gamma. It has no effect on dE. On the other hand, under the color gamut tab, changes in L certainly do affect the calculated dE value because here the app uses a 3-D calculation. This is the correct implementation, which is why I wrote that Y is relevant for color measurements, but not for grayscale.

http://home.comcast.net/%7Etlhuffman/accupel1.gif

http://home.comcast.net/%7Etlhuffman/accupel2.gif

Second, having made that distinction, I am not sure what you mean when you write that "We (calibrators) don't typically USE dE with grayscale measurements. . . ." I assume what you meant to say here was we don't typically use 3-D measurements for the grayscale.

Yes, of course, 3-D dE is not used with grayscale adjustments. Typo on my part, should have specified.



Third, I really don't know what you mean when you write that "Before starting, you'd have to enter a Gamma target value along with a reference white measurement so L or Y target values could be calculated for each step in the grayscale. This is all done in the AccuPel Calculator tool. . . ."

You cut the quote off a little prematurely...

"... and in CalMAN without ever coming out and expressing the actual [3-D] dE number... you do get a target value for L or Y and it's up to you to adjust Y or L to get as close as possible to the target value."

My point being, a 3-D dE COULD have been used - everything you need for the calculation is there, it's just that there was a decision made to use a 2-D dE number with L or Y target and measurement shown separately. Which is the right thing to do when there are no controls for L or Y for each grayscale step - which is either universal or nearly universal in video displays. A device like the Lumagen Radiance XD has 3-D adjustments for each step in the grayscale but a 3-D dE number doesn't tell you anything about the direction you are "off" in (nor does a 2-D dE number for that matter) so using a 3-D dE number even if the device has 3-D controls isn't going to make the cal any easier. The best tools give you graphical or data feedback so you know whether a color is dominant or luminance is off... makes it easier to know which control to adjust and what direction to go in.


This is NOT how Greg's Display Calibration app handles dE for gray scale measurements. The app has two tabs, one for gray scale and one for color gamut. In the grayscale section, the dE values calculated are strictly 2-D. You can change the target gamma to anything you like and that does not affect the dE calculation, as shown below. In fact, the app allows you the ability to enter the measured Y values in the grayscale section only for the purpose of seeing the gamma. It has no effect on dE. On the other hand, under the color gamut tab, changes in L certainly do affect the calculated dE value because here the app uses a 3-D calculation. This is the correct implementation, which is why I wrote that Y is relevant for color measurements, but not for grayscale.

My point is/was that Y is as relevant for grayscale as it is for color. Only we tend to think of Y in terms of Gamma and that historically we haven't had step-by-step control of Y. Including Y in color measurement dEs is no more or less helpful to calibrators than not including Y in the color dEs. You could just as easily have 2-D dE calculations for color and a separate Y - for a truly functional CMS with 3 sliders per color, that would actually make adjusting the color points easier for R, G, and B since each of those colors would have a slider that affects Y only (you hope).

In the end, a 3-D dEs for grayscale measurements would/will tell you exactly the same thing as a 3-D dE for a color... how far the measured point is from the reference point. For colors, your reference point is established by SMPTE-C or Rec 709. For grayscale, your xy reference points are always the same and your Y reference point is established by your white and/or black points and your target Gamma. 3-D dEs are problematic for that simple reason that if the dE is 6... the error can be in any direction. Just because they are used with colors doesn't make them any easier to use... frankly, I'd be perfectly happy with 2-D dE plus Y for colors also.

I guess my point was that dE is a simple expression that can be 2-D or 3-D in any color space. What we do with it as calibrators is not the limitation - it's a convention, either habitual or for good reason (or both). A point on the grayscale can just as easily have a 2-D or 3-D dE number associated with it if that's what you want to do - though you may have to make your own spreadsheet to do so. [in fact, you could even have a 1-dimensional dE... a dE for x, a dE for y, a dE for Y - but you still wouldn't know the direction of the error].

You cut the quote off a little prematurely...

"... and in CalMAN without ever coming out and expressing the actual [3-D] dE number... you do get a target value for L or Y and it's up to you to adjust Y or L to get as close as possible to the target value."Doug: I cut the quote off at that point intentionally. I don't dispute that CalMan offers this as an option. I have already argued at length with Bill Blackwell about this. What I disputed was your misleading claim that CalMan AND Greg's Display Calibration app offer this as though there were some general consensus on the point, when in fact CalMan is an outlier on this issue. I merely objected to your lumping them together in this regard as though they were the same. OK, enough on that.

My point being, a 3-D dE COULD have been used - everything you need for the calculation is there, it's just that there was a decision made to use a 2-D dE number with L or Y target and measurement shown separately. Which is the right thing to do when there are no controls for L or Y for each grayscale step - which is either universal or nearly universal in video displays. A device like the Lumagen Radiance XD has 3-D adjustments for each step in the grayscale but a 3-D dE number doesn't tell you anything about the direction you are "off" in (nor does a 2-D dE number for that matter) so using a 3-D dE number even if the device has 3-D controls isn't going to make the cal any easier. The best tools give you graphical or data feedback so you know whether a color is dominant or luminance is off... makes it easier to know which control to adjust and what direction to go in.

My point is/was that Y is as relevant for grayscale as it is for color. Only we tend to think of Y in terms of Gamma and that historically we haven't had step-by-step control of Y. Including Y in color measurement dEs is no more or less helpful to calibrators than not including Y in the color dEs. You could just as easily have 2-D dE calculations for color and a separate Y - for a truly functional CMS with 3 sliders per color, that would actually make adjusting the color points easier for R, G, and B since each of those colors would have a slider that affects Y only (you hope).

In the end, a 3-D dEs for grayscale measurements would/will tell you exactly the same thing as a 3-D dE for a color... how far the measured point is from the reference point. For colors, your reference point is established by SMPTE-C or Rec 709. For grayscale, your xy reference points are always the same and your Y reference point is established by your white and/or black points and your target Gamma. 3-D dEs are problematic for that simple reason that if the dE is 6... the error can be in any direction. Just because they are used with colors doesn't make them any easier to use... frankly, I'd be perfectly happy with 2-D dE plus Y for colors also.

I guess my point was that dE is a simple expression that can be 2-D or 3-D in any color space. What we do with it as calibrators is not the limitation - it's a convention, either habitual or for good reason (or both). A point on the grayscale can just as easily have a 2-D or 3-D dE number associated with it if that's what you want to do - though you may have to make your own spreadsheet to do so. [in fact, you could even have a 1-dimensional dE... a dE for x, a dE for y, a dE for Y - but you still wouldn't know the direction of the error].I said in my last post that I wasn't sure if I disagreed with you or not. Now I am sure I do. You make several claims here.

1. You COULD use 3-D dE for grayscale if you wanted to to.
2. The only reason that 3-D isn't used for grayscale is because of a lack of controls.
3. Y is equally important for grayscale dE as it is for color dE.

I think that these are fair summaries. If not, then please correct them. Let's take them one at a time.

1. Of course, one can use 3-D dE for grayscale. The fact that CalMan does it is conclusive evidence that it is possible. This issue isn't whether it is technically feasible, but whether doing so is a good idea. I think that it is abundantly clear that it is not. So clear, in fact, that I am surprised that I find myself having this debate for the second time in a month.

2. The lack of controls is not relevant at all. There are, in fact, MORE options for control of the Y parameter for white in high-end AV equipment than there is for color. Point-by-point gamma adjustment, such as what the Lumagen offers is available in other products as well, including the new JVC line of LCoS PJs. However, this degree of control of the brightness of color is unheard of. Many CMS's leave Brightness off entirely, and the ones that offer some adjustment (Lumagen incuded) offer it at one global level only. So, the industry has not adopted the practice of using Y in grayscale dE, despite the presence of quite a bit of adjustibility, especially relative to what's been available for color.

3. The issue isn't whether the Y component is important for grayscale in general. Of course, it is. The issue is whether the Y component should be included in dE calculations for the grayscale. These are related, but separate, issues. I only dispute the latter.

So it all comes to whatever reasons can be offered for or against doing so. I think that the reasons are overwhelmingly in favor of NOT doing so.

1. If you include Y in dE calculations for white, then it leads to a peculiar situation in which the same color of white at different levels of stimulus has a different dE, indeed radically different dEs, rendering the entire metric effectively meaningless. Let's take the quite green x0.311, y0.341. This results in

R91
G103
B93

From a calibration standpoint, this is an unacceptible grayscale error by any reasonable standard. Or, is it? SMPTE has specified 4 dE (in Lab units) as the outer limit of color error. If we include Y in our grayscale calculation of dE, then, assuming a 2.2 gamma, at 20% and 30% stimulus x0.311, y0.341 is a perfectly acceptable result, because the Lab dE at those levels using this methodology would be 2.5 and 3.3, respectively, and that assumes a perfect gamma response. This is true despite the fact that at 90% stimulus, the same color of white has a dE of 7.5.

Doug, this is a ludicrous result. I know of no reputable calibrator, including you, who would accept x0.311, y0.341 as an acceptible target for gray scale calibration, but that is precisely what this methodology would have us do at the low end--that is, if we are to take dE seriously. And that's my point. If you use this methodology, then dE for white is rendered nearly meaningless.

There are other reasons as well, but this one consideration is so compelling that all other factors are secondary.

Doug: I cut the quote off at that point intentionally. I don't dispute that CalMan offers this as an option. I have already argued at length with Bill Blackwell about this. What I disputed was your misleading claim that CalMan AND Greg's Display Calibration app offer this as though there were some general consensus on the point, when in fact CalMan is an outlier on this issue. I merely objected to your lumping them together in this regard as though they were the same. OK, enough on that.

Yes, Tom, we've gone over this. Here (http://www.avsforum.com/avs-vb/showthread.php?t=1087084). I'm still waiting on the answers to a few questions. But then, I'm an outlier, apparently. So is the CIE, but I guess they aren't important. SMPTE isn't either, as well, apparently, but they are beside the point. As I said, your beef is with the CIE, not us, but let's see if anything has sunk in, or if you are going to continue publishing both misleading and ironic articles. I only have two questions here, and then I'll go away.

1. If you include Y in dE calculations for white, then it leads to a peculiar situation in which the same color of white at different levels of stimulus has a different dE, indeed radically different dEs, rendering the entire metric effectively meaningless. Let's take the quite green x0.311, y0.341. This results in

R91
G103
B93

From a calibration standpoint, this is an unacceptible grayscale error by any reasonable standard. Or, is it? SMPTE has specified 4 dE (in Lab units) as the outer limit of color error. If we include Y in our grayscale calculation of dE, then, assuming a 2.2 gamma, at 20% and 30% stimulus x0.311, y0.341 is a perfectly acceptable result, because the Lab dE at those levels using this methodology would be 2.5 and 3.3, respectively, and that assumes a perfect gamma response. This is true despite the fact that at 90% stimulus, the same color of white has a dE of 7.5.

Doug, this is a ludicrous result. I know of no reputable calibrator, including you, who would accept x0.311, y0.341 as an acceptible target for gray scale calibration, but that is precisely what this methodology would have us do at the low end--that is, if we are to take dE seriously. And that's my point. If you use this methodology, then dE for white is rendered nearly meaningless.

1) Given that either flavor of the 1976 formula is basically a modified Cartesian distance, why is color error based on a (-0.002, +0.012) difference in white irrelevant for changes in luminance, but the same magnitudes of error in red, green or blue should use luminance?

2) Why is someone who is purporting to be an expert in color error talking about things in the xy plane, which is nowhere close to being perceptually uniform with respect to saturation and hue?

And this time, answer the above questions. Don't try to distract people by talking about me. Let's actually talk about the actual theory and practice this time.

Bill

By the way, if anyone is curious what SpectraCal really recommends for its customers, Derek posted it here:
http://www.avsforum.com/avs-vb/showpost.php?p=15130318&postcount=7

Yes, Tom, we've gone over this. Here (http://www.avsforum.com/avs-vb/showthread.php?t=1087084). I'm still waiting on the answers to a few questions. But then, I'm an outlier, apparently. So is the CIE, but I guess they aren't important. SMPTE isn't either, as well, apparently, but they are beside the point. As I said, your beef is with the CIE, not us, but let's see if anything has sunk in, or if you are going to continue publishing both misleading and ironic articles. I only have two questions here, and then I'll go away.Bill, CIE establishes general standards for color. It does not get into the weeds of how specific industries implement those standards. If the CIE has published standards for how to use dE in grayscale evaluation, then I'd love to read it. If you are correct, then the entire video industry ignores CIE. Not just me. Again, this is not personal. I don't have a beef against you or against Derek. Aside from being more than a little over-sensitive, you seem like a nice guy. This a substantive disagreement not a pissing match.

1) Given that either flavor of the 1976 formula is basically a modified Cartesian distance, why is color error based on a (-0.002, +0.012) difference in white irrelevant for changes in luminance, but the same magnitudes of error in red, green or blue should use luminance?

2) Why is someone who is purporting to be an expert in color error talking about things in the xy plane, which is nowhere close to being perceptually uniform with respect to saturation and hue?

And this time, answer the above questions. Don't try to distract people by talking about me. Let's actually talk about the actual theory and practice this time.This is called projection. You make a series of rather personal, sarcastic, and not very professional comments and then accuse me of "talking about you." As Doug has already commented on above, I went to almost comical lengths to avoid mentioning you.

I have already explained at length why a correct implementation of dE includes considering luminance for color and ignoring it for white in our previous debate and I summarized again just above. If anyone is interested in a more comprehensive list of reasons, you only need consult the thread you link to above. I don't see much point in repeating it again. However, I just realized that you had continued with that thread, so I'll now go back to that and answer all of your substantive questions there. I'll try to ignore the personal stuff.

I've got a question for you. Can you name one reputable calibrator--just one--who would consider x0.311, y0.341 an acceptable result for grayscale calibration at 20 or 30 stim? Can you name a single commercial publication that cites grayscale dE that uses this methodology? Just one?

Why am I talking about things in the xy plane? Well, gee, I guess because xy coordinates are the common industry standard for discussing color. You must agree with me because that's what your software displays. The fact that xyY has to be converted to a more perceptually uniform standard prior to dE calculation is something I refer to in this thread and have referred to countless times in the past, which you well know. This silly attempt to make it seem that I don't know something that I refer to on almost a daily basis is not worthy of you.

I have a question that I need help with. I have a set that has desaturated red that I just cant push any farther. its close but not quite there yet. my delta E measures lower when reds value for Y, calculated from the Rec 709 chart, is higher than it is supposed to be. when I try to dial down the value to get it closer to where the correct value is, the delta E gets higher. I thought it would get lower. the color point on the cie diagram stays in the same position. whats going on here. according to delta E it would seem like I should adjust the gain for red up to compensate for its desaturation. is this correct. or should I ignore delta E and get that gain as close as possible. I hope i'm making sense.


Despite all the posts above, I can shed some light on your question very easily.

Joel @ ISF believes you need to go by the numbers and not dE.

THX teaches dE is the end all - get it to within 3.0 and "call it a day".

If you are wondering why there is such controversy in the past 22 posts, just think about the difference of opinion between ISF and THX - then you can understand where all the posts from above are coming from.

Doug: I cut the quote off at that point intentionally. I don't dispute that CalMan offers this as an option. I have already argued at length with Bill Blackwell about this. What I disputed was your misleading claim that CalMan AND Greg's Display Calibration app offer this as though there were some general consensus on the point, when in fact CalMan is an outlier on this issue. I merely objected to your lumping them together in this regard as though they were the same. OK, enough on that.

I specifically did NOT say Greg's calculator offers 3-D dE... I said what I meant in the quote - you don't get a 3-D dE calculation, but everything is there (in the calculator) and there COULD be a 3-D dE calculation from the data you input into a calculator (or your own spreadsheet.

I also pointed out dE could be 1-dimensional, 2-dimensional, or 3-dimensional. dE has no "limits" it can always be calculated any way the user of dE sees fit. I also didn't say using a 3-D dE with grayscale measurements was desirable or helpful or perceptually accurate or anything else... only that it can be done. A 3-D dE calculation can be performed on any point in a color space. Where and when it is helpful is up to the person using it.

My original response was you your reply to another post that made it sound like it is not possible to use a 3-D dE with a grayscale measurement... it clearly is POSSIBLE. And that was the main point I was trying to make. And secondarily, just because you CAN do a 3-D dE for a grayscale measurement doesn't mean you SHOULD... for a range of reasons.

The upper limit for dE is a complex subject - as is color coordinates and perceptual differences. Every color space has examples where minor differences in coordinates are far more visible than dE or the coordinates themselves would lead you to believe. Even the so-called "more perceptually accurate" color spaces have many problematic regions and it's not just on the white-gray-black axis.

There is a big difference between possible and desirable and I never said a 3-D dE number for grayscale measurements was DESIRABLE. I did say you could do it if you wanted to do it - and that is 100% true. Why you would want to do it... I can't think of a good reason. But you COULD if you wanted to.



I said in my last post that I wasn't sure if I disagreed with you or not. Now I am sure I do. You make several claims here.

1. You COULD use 3-D dE for grayscale if you wanted to to.
2. The only reason that 3-D isn't used for grayscale is because of a lack of controls.
3. Y is equally important for grayscale dE as it is for color dE.

I think that these are fair summaries. If not, then please correct them. Let's take them one at a time.

1. Of course, one can use 3-D dE for grayscale. The fact that CalMan does it is conclusive evidence that it is possible. This issue isn't whether it is technically feasible, but whether doing so is a good idea. I think that it is abundantly clear that it is not. So clear, in fact, that I am surprised that I find myself having this debate for the second time in a month.

For me the issue was the 2 sequential posts (another poster and yours) coming together to make it sound like a 3-D dE for a grayscale measurement was impossible... it is not and that's the ONLY point I was trying to make. #1 is completely true. You could also disregard SMPTE's limit of "4" and make the limit anything you want it to be, including less than 1 if you wanted to and if you had the control precision to reach that level of accuracy.



2. {snip} So, the industry has not adopted the practice of using Y in grayscale dE, despite the presence of quite a bit of adjustibility, especially relative to what's been available for color.

Again, the point (in my mind when I made the original post) wasn't whether 3-D dE for grayscale was good practice or not. My only point was that you can just as well calculate a 3-D grayscale dE as you can a 3-D dE for any other point in the color space.


3. The issue isn't whether the Y component is important for grayscale in general. Of course, it is. The issue is whether the Y component should be included in dE calculations for the grayscale. These are related, but separate, issues. I only dispute the latter.

I don't think your #3 summarizes anything I said... unless I wasn't clear about something (always possible). I never said Y was just as important for grayscale dE... in fact, I gave a number of reasons why it wasn't helpful.


So it all comes to whatever reasons can be offered for or against doing so. I think that the reasons are overwhelmingly in favor of NOT doing so.

Agreed, but someone could still do it if they wanted to. The 2 posts I was responding to made it sound like you COULDN'T do a 3-D dE for a grayscale adjustment.

Agreed, but someone could still do it if they wanted to. The 2 posts I was responding to made it sound like you COULDN'T do a 3-D dE for a grayscale adjustment.Oh, OK. If that's all you meant to say, then I certainly have no problem with that. Much ado about nothing. . . .

This discussion is very interesting. If a calibrators goal is to set up a display so the program material is seen by the viewer as the director intended (and I think it is), then we need to use the criteria the director/production houses use. This would be whether you think it is correct or incorrect.

So my question is to those who calibrate production displays is, what specifications do you use? If the answer is inconsistent, then there are not "standards". Just my view of the world.

Despite all the posts above, I can shed some light on your question very easily.

Joel @ ISF believes you need to go by the numbers and not dE.

THX teaches dE is the end all - get it to within 3.0 and "call it a day".

If you are wondering why there is such controversy in the past 22 posts, just think about the difference of opinion between ISF and THX - then you can understand where all the posts from above are coming from

First, let me say that I do not have near the level of color science knowledge that many of you here possess and I thank you all for the heated debate that is both fascinating and educational. I would tend to agree with tomhuffman on the whole factoring Y values into delta E for gray is not a good idea. That would just confuse amateurs like myself. I would prefer to look at gamma and gray scale as two separate issues and have my delta e simply take into account the xy values of gray, especially considering I don't have independent Y control for each ire level of gray. BTW, sorry for referring to it as ire level but I am a newbie.

Let me see if i understand this correctly. Here's my analogy of you guys argument on factoring y in gray scale delta e. Basically, I could technically jump off a cliff if I wanted to but that doesn't mean i should. thanks for clearing that up. In all seriousness, this is a fascinating subject and I greatly appreciate your comments.

As far as Joe Kane's preference for following numbers and ignoring delta e, I think that is incorrect. I respect Joe Kane immensely and perhaps i am speaking blasphemy here but I think that delta e is there for a reason and so I will consider it.

It seams to me that what is going on in my case is, because my blue is desaturated I should push my Y value for blue to compensate for this and thus giving more of a perception of being closer to accurate. that's at least what delta e is telling me so that's what I have done. I can't get delta e for my blue below 5.6. all other colors are 2 or below. that's just the limit of my sets capability, I guess.

Another point I would make is that THX is involved in the mastering of many movies so if they say to follow delta e, wouldn't it make sense to listen to there advice for the sake of matching the intended look of there movies?

Sorry for my ignorance.

First, let me say that I do not have near the level of color science knowledge that many of you here possess and I thank you all for the heated debate that is both fascinating and educational. I would tend to agree with tomhuffman on the whole factoring Y values into delta E for gray is not a good idea. That would just confuse amateurs like myself. I would prefer to look at gamma and gray scale as two separate issues and have my delta e simply take into account the xy values of gray, especially considering I don't have independent Y control for each ire level of gray. BTW, sorry for referring to it as ire level but I am a newbie.

Let me see if i understand this correctly. Here's my analogy of you guys argument on factoring y in gray scale delta e. Basically, I could technically jump off a cliff if I wanted to but that doesn't mean i should. thanks for clearing that up. In all seriousness, this is a fascinating subject and I greatly appreciate your comments.

As far as Joe Kane's preference for following numbers and ignoring delta e, I think that is incorrect. I respect Joe Kane immensely and perhaps i am speaking blasphemy here but I think that delta e is there for a reason and so I will consider it.

It seams to me that what is going on in my case is, because my blue is desaturated I should push my Y value for blue to compensate for this and thus giving more of a perception of being closer to accurate. that's at least what delta e is telling me so that's what I have done. I can't get delta e for my blue below 5.6. all other colors are 2 or below. that's just the limit of my sets capability, I guess.

Another point I would make is that THX is involved in the mastering of many movies so if they say to follow delta e, wouldn't it make sense to listen to there advice for the sake of matching the intended look of there movies?

Sorry for my ignorance.

Not Joe Kane - Joel Silver who is the head of ISF.

And I probably should point out that I cannot say with 100% confidence what THX's position is - its actually the position of the THX Video Instructors who are not actually THX Employees but developed the calibration course and teach it for THX. I am sure they can shed some light on it if they want.

sorry my mistake.

Bill, CIE establishes general standards for color. It does not get into the weeds of how specific industries implement those standards. If the CIE has published standards for how to use dE in grayscale evaluation, then I'd love to read it.
I also reference SMPTE, which you have ignored. Please read SMPTE Engineering Guideline 432-1, especially appendix L. I will quote the relevant sections here to save folks the cost of buying it from the SMPTE store. I HIGHLY recommend that pro calibrators join SMPTE, if only for the discounts for SMPTE publications.

So that I do not create a monster post (it's going to be big, as it is), and I stay within fair use doctrine for copyrighted materials, I am only going to post excerpts. If you want to double-check that I am not quoting things out of context, please purchase the document I reference for yourself. Note: you can get some of this content, but with some odd contradictions, from www.dcimovies.com (http://www.dcimovies.com), though do realize that SMPTE Engineering Guidelines are authoritative.

If you are correct, then the entire video industry ignores CIE. Not just me. Again, this is not personal. I don't have a beef against you or against Derek. Aside from being more than a little over-sensitive, you seem like a nice guy. This a substantive disagreement not a pissing match.
So, let's try to establish a few things:
1) What are the properties of a color error equation?
2) Should there be any differences as it applies to grayscale and why?
3) What is the best way to quantify these adjustments?

Let's turn to Appendix L, it's a good treatment of a topic I have, so far, been unsuccessful in getting you to understand:

The Munsell color space is the most uniform color space. - It was defined by having many people make many judgements of color differences using color patches. One problem with the Munsell space is that it was based on judgements of color patches and it is not based on any mathematical equations. The CIELab space is a mathematical approximation, based on XYZ tristimulus values and Equations L-1 to L-13, of the Munsell space. But the equations that define the CIELab space do not exactly describe the Munsell space. Therefore the CIELab space is not perfectly uniform, but is sufficiently uniform for most uses.
So, one of the issues we are dealing with is that we have to give up some perceptual uniformity for quantification and ease-of-modeling. The implications here is that at some places, the perceptual side will break down, but the benefits gained in terms of predictive capabilities outweigh these point failures. In other words, nothing is perfect.

Further in the same paragraph:
There is a general rule of thumb that says that when comparing two color patches, which are placed near each other, which are near neutral in color, and which are in the environment specified for judging colors in the Munsell color system, a delta E*ab = 1 is at or near the threshold of visibility of the color difference for most people. If any of these conditions is changed, for example the environment is changed or the colors are very colorful instead of being near neutral or the colors are presented sequentially at very low frequency, not simultaneously, the threshold of visibility of the color difference increases. This means that for any of these different conditions, in order for a person to see the color difference, the delta E*ab will increase. Conversely, for any of these different conditions, a pair of color patches with a given delta E*ab will appear to be less different than if they were in the environment specified for judging colors in the Munsell color system. For the case in which the two colors are highly colored, the threshold of the visibility of the color difference increases to a delta E*ab of about 2. The result of this is that because the illuminance levels in a theatre are much lower than were used to define the Munsell space and because the color differences are between colors in one theatre using one projector and colors in another theatre using another projector, this delta E*ab of 4 is visually a very tight tolerance. In fact, few, if any, people will be able to detect the color difference between two colors from the same code values in two different theatres if both theatres and projectors are set up to these tolerances.

(Emphasis mine) While a reference back to the origin of the "4 dE" standard is not made in the text, its validity is based upon studies done by SMPTE. Do note, though, that this is for fully-specified Lab. Also note the reference to the "dim" environment in a typical theater. Color differences have been demonstrated to be harder to see where light levels are lower. Let's see how this translates back to the xy plane:

In the a*b* diagram for each primary there are four circles for the four levels of luminance around each primary. The four circles for each primary are not all centered at the same a*b* values, but instead fall on a line from the a*b* values of the primary at its highest luminance to the neutral axis. The circle corresponding to the 0.5% luminance patch is the closest to the neutral axis. In the chromaticity diagram, the reference point of the tolerance figures is located at the same xy chromaticity coordinates independent of the luminance value. However, although all of the tolerance figures were circles of radius 4 in the a*b* diagram, the tolerance figures in the xy diagram increase in size with decreasing luminance.

(Again, emphasis mine) Here we see the difference between what one gets at the periphery versus at the "neutral" (i.e., gray/white) point. Again, for copyright purposes, I am attaching only the part figure L-2 where a constant dE of 4 (with dL = 0) is re-cast from the ab plane to an xy plane. What is notable is the absence of a discussion here of using a different calculation approach to dE for work in the gamut versus the grayscale.

Having worked through the introductory material in the appendix, let's look to section 6, Measurement of Projected Images (seems relevant). On page 13, you see the chromaticity and luminance targets and tolerances for reference theaters, review rooms and general exhibition theaters. Here we get a bit of irony, there is a +/- 0.002 deviation allowed for deviation in x or y, even though the perceptibility of these deviations is not constant. In practice, these should be very small, though. These are well within the measurement confidence interval for ordinary colorimeters. For luminance, the reference is 14ftL (unambigous) with a tolerance of +/- 1 ftL for review rooms (also unambiguous).

The tolerance for luminance is given in terms of a variance on gamma, rather than a variance in dE. SMPTE uses an ordinary power curve, with the computation being done in a log-log fashion. Reference slope (i.e., gamma exponent) is 2.6, with a tolerance for reference rooms of 2.548 to 2.652 (+/- 0.52). So, this is pretty important. What have we learned:



SMPTE uses dE(76, Lab)
The amount of saturation/hue error that is perceptible varies with changes in adapted light level.

Error in luminance is a "measure of concern" to SMPTE, but is measured in terms of gamma deviation, rather than dE -- until we get to section 6.13.
Section 6.13 gives us the method for verifying the color accuracy of the entire system using 12 measures, two each for RGBCMY. Here, the standard of dE(ab) being <= 4 is reasserted. Since white/gray is a color, presumably these also fall within this standard, though in reality, the tolerances given previously are a tighter standard.

Within the minimum color gamut specified for the Reference Projector, all colors need to be accurately reproduced within a tolerance of 4 delta E*ab. A discussion of delta E*ab is given in Appendix L. In theory this applies to all colors, but in practice it would be impossible to display and measure all possible colors that can be encoded by the DCDM color encoding equations and displayed by a Reference Projector. Therefore Table 6-11 gives a set of colors that can be used to verify the color accuracy of a system. It is felt that if these colors are within the tolerance limits, then all colors are most likely within the tolerances. The neutral colors 6 through 10 in Table 6-7 may also be used as tests of the color accuracy of any projector in its environment.

So, given this, the obvious question is "why does CalMAN advocate anything different from SMPTE?" The reason is that until relatively recently, there were not ways for people to manipulate the gamma performance of their displays, so we wanted a method that preserves the (desirable) characteristic of color error diminishing as light level decreases, while, at the same time, giving our predominantly enthusiast customers clear guidance that was usable in a typical home environment with home tools (e.g., a 0.002 tolerance does you no good if your meter's limit under best circumstances is 0.004). In this respect, we use uv, rather than ab, because uv is better than xy, and at least a few publications (e.g., WSR) use it. Once you move beyond dE(76), you are "stuck" with Lab, so there is no uv vs. ab controversy there, only threads like this.


You must agree with me because that's what your software displays.
CalMAN displays a lot of things. Our goal is to provide the user as much information as possible. In terms of gamut charts, we prefer/recommend people use a uv chart, but there is only so much that education and outreach can do, as my efforts here prove.

I've said it before, and I'll say it again: dE(uv) provides a much more aggressive standard than either of the dE(76) methods. People who use it should feel confident that they are not going to encounter visible errors resulting from problems in saturation or hue. For an enthusiast, this may be too aggressive, at which point, CalMAN offers several alternatives.

If this is sufficient, then I'm not really sure what is.

Bill

If this is sufficient, then I'm not really sure what is.Nothing you have quoted here speaks to what we have been arguing about, which is two approaches to employing dE for grayscale measurements. Indeed, nothing in this lengthy series of quotes even mentions grayscale tracking.

I think that we should just agree to disagree and leave it at that.

It seams to me that what is going on in my case is, because my blue is desaturated I should push my Y value for blue to compensate for this and thus giving more of a perception of being closer to accurate. that's at least what delta e is telling me so that's what I have done. I can't get delta e for my blue below 5.6. all other colors are 2 or below. that's just the limit of my sets capability, I guess.


Y doesn't have anything to do with saturation though. Y is brightness. So you are undersaturated (this means, literally, that your measured blue point is INSIDE the reference color space triangle you are using... HDTV/709 or SD/SMPTE-C). All Y will do is make that shade of blue lighter or darker, it won't move the measured point farther out towards the correct reference point. So altering the Y will INCREASE your error for that point, not decrease it. Your lowest error will be with Y as close to the reference Y for Blue as you can get, and the x & y points as close to the reference x & y as you can get. If your blue really is desaturated, there's really nothing you can do to pump it up to look right. In otherwords, if you increase Y trying to compensate for the desaturated condition, you will make every color that contains blue even less accurate than they are with Y set close to the reference value for Blue Y.

thanks for being clear. yes I am perfectly aware that Y is luminance and willl not directly effect saturation and hue. I have tried putting my blue luminance at the correct setting according to this formula

Rec. 709 (High Definition)
--------------x-------y-------Y
Red----------0.640---0.330---0.2127
Green--------0.300---0.600---0.7151
Blue----------0.150---0.060---0.0722
Yellow--------0.419---0.505---0.9278
Cyan---------0.225---0.329---0.7873
Magenta------0.321---0.154---0.2849
White--------0.3127--0.329---1.0

so basically it was done this way
100% white luminance X 0.08 = luminance for blue
this gives me a worse delta E than where I have it .

the next thing you might assume is that my meter is off but I have confirmed with acupel calculator and got close to the same result.

based on this I can only assume that even though luminance doesnt effect saturation, having a slightly brighter less saturated color is beter than having a accurate luminance with a les saturated color.

this will not through off all my other colors because I am working with a five stage (possible 6 stage) color wheel and each of the six colors can be adjusted independently and without effecting the other.

here once again I go back to my original question of weather or not to believe in delta e or go by the numbers.

thanks for being clear. yes I am perfectly aware that Y is luminance and willl not directly effect saturation and hue. I have tried putting my blue luminance at the correct setting according to this formula

Rec. 709 (High Definition)
--------------x-------y-------Y
Red----------0.640---0.330---0.2127
Green--------0.300---0.600---0.7151
Blue----------0.150---0.060---0.0722
Yellow--------0.419---0.505---0.9278
Cyan---------0.225---0.329---0.7873
Magenta------0.321---0.154---0.2849
White--------0.3127--0.329---1.0

so basically it was done this way
100% white luminance X 0.08 = luminance for blue
this gives me a worse delta E than where I have it .

the next thing you might assume is that my meter is off but I have confirmed with acupel calculator and got close to the same result.

based on this I can only assume that even though luminance doesnt effect saturation, having a slightly brighter less saturated color is beter than having a accurate luminance with a les saturated color.

this will not through off all my other colors because I am working with a five stage (possible 6 stage) color wheel and each of the six colors can be adjusted independently and without effecting the other.

here once again I go back to my original question of weather or not to believe in delta e or go by the numbers.

The THX classes, the dE 3.0 or less (not go by the numbers as Joel teaches) even states that after everything you put up known material and the final check is a visual check using known material using your eyes.

If you say it looks wrong using dE, you have made the decision yourself.

thanks for being clear. yes I am perfectly aware that Y is luminance and willl not directly effect saturation and hue. I have tried putting my blue luminance at the correct setting according to this formula

Rec. 709 (High Definition)
--------------x-------y-------Y
Red----------0.640---0.330---0.2127
Green--------0.300---0.600---0.7151
Blue----------0.150---0.060---0.0722
Yellow--------0.419---0.505---0.9278
Cyan---------0.225---0.329---0.7873
Magenta------0.321---0.154---0.2849
White--------0.3127--0.329---1.0

so basically it was done this way
100% white luminance X 0.08 = luminance for blue
this gives me a worse delta E than where I have it .

the next thing you might assume is that my meter is off but I have confirmed with acupel calculator and got close to the same result.

based on this I can only assume that even though luminance doesnt effect saturation, having a slightly brighter less saturated color is beter than having a accurate luminance with a les saturated color.

this will not through off all my other colors because I am working with a five stage (possible 6 stage) color wheel and each of the six colors can be adjusted independently and without effecting the other.

here once again I go back to my original question of weather or not to believe in delta e or go by the numbers.

Do the Greyramp patterns look completely nuetral before you even get into this attempt at color decoding correction and saturation/hue adjustments?

Logic dictates that if there is tinting in greyramps to your eye regardless of dE for greyscale, then everything else is crap. Greyscale has to be visually confirmed before moving on is what my mind tell me.

I have had times playing with my cuts and drives and had RGB fairly well balanced and dE's 4 or less across the greyscale run and then the temp graph showed that I was giong below D65 and above D65 from one step to the next. The ones that were D65 or above looke great in the Greysteps but the ones that dipped below D65 appeared pink and a few of them a touch green.

I am assuming that that would effect how color ends up looking right?

C.

thanks for being clear. yes I am perfectly aware that Y is luminance and willl not directly effect saturation and hue. I have tried putting my blue luminance at the correct setting according to this formula

Rec. 709 (High Definition)
--------------x-------y-------Y
Red----------0.640---0.330---0.2127
Green--------0.300---0.600---0.7151
Blue----------0.150---0.060---0.0722
Yellow--------0.419---0.505---0.9278
Cyan---------0.225---0.329---0.7873
Magenta------0.321---0.154---0.2849
White--------0.3127--0.329---1.0

so basically it was done this way
100% white luminance X 0.08 = luminance for blue
this gives me a worse delta E than where I have it .

the next thing you might assume is that my meter is off but I have confirmed with acupel calculator and got close to the same result.

based on this I can only assume that even though luminance doesnt effect saturation, having a slightly brighter less saturated color is beter than having a accurate luminance with a les saturated color.

this will not through off all my other colors because I am working with a five stage (possible 6 stage) color wheel and each of the six colors can be adjusted independently and without effecting the other.

here once again I go back to my original question of weather or not to believe in delta e or go by the numbers.

If you are trying to measure the gamut with a consumer-oriented colorimeter, go with your eyes. If you've got an i1 Pro, re-calculate the color balance ratios, and then re-take the measurements to see what your actual targets are (per Tom's suggestion from post #2).

thanks for being clear. yes I am perfectly aware that Y is luminance and willl not directly effect saturation and hue. I have tried putting my blue luminance at the correct setting according to this formula

Rec. 709 (High Definition)
--------------x-------y-------Y
Red----------0.640---0.330---0.2127
Green--------0.300---0.600---0.7151
Blue----------0.150---0.060---0.0722
Yellow--------0.419---0.505---0.9278
Cyan---------0.225---0.329---0.7873
Magenta------0.321---0.154---0.2849
White--------0.3127--0.329---1.0

so basically it was done this way
100% white luminance X 0.08 = luminance for blue
this gives me a worse delta E than where I have it .

the next thing you might assume is that my meter is off but I have confirmed with acupel calculator and got close to the same result.

based on this I can only assume that even though luminance doesnt effect saturation, having a slightly brighter less saturated color is beter than having a accurate luminance with a les saturated color.

this will not through off all my other colors because I am working with a five stage (possible 6 stage) color wheel and each of the six colors can be adjusted independently and without effecting the other.

here once again I go back to my original question of weather or not to believe in delta e or go by the numbers.

There are different dEs and depending on which one you are using, the "limits" you want to use are also different. dExy (there are more than 1 of these based on the CIE standard selected, usually going by the year the standard was adopted) and dEuv produce different dE numbers for the same coordinates.

Rounding .0722 to .08 will increase your error. If you are going to round .0722, going DOWN to .07 times the 100% white luminance will decrease your error.

If your meter isn't accurate, the Accupel calculator won't improve your results or confirm anything about the accuracy of the meter. Using 2 different calculation methods with a meter that's not providing accurate readings won't reveal anything - except you may get similar results for the 2 calculation methods. That doesn't mean the meter is accurate. Doesn't mean it's inaccurate either.

Have you tried using a "cooler" color temp setting to see if your blue point, just by luck, is more saturated? If the color temp setting moves the blue point in the right direction, you'll probably have better luck bringing green and red "in" towards the correct reference points.