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Basic Guide to Color Calibration using a CMS (updated and enhanced) - Page 55

post #1621 of 1936
Quote:
Originally Posted by TomHuffman View Post

That's how I understood the post. I can only repeat my reply. 100% saturation simply means a particular shade of red in the Rec. 709 gamut. I can think of no reason why THAT shade of red would be any more or less represented in the real world than other shades of red, 75% in particular. Think of the red one sees in a red rose. My guess is that that's more saturated than 100% Rec. 709, not less.

Using 75% as a target to minimize dE errors across the range of saturations within the gamut is a perfectly reasonable approach, but that strategy--even if successful--says nothing about what level of saturation is more typical in available content.

Thanks, Tom. So I guess the answer is that it depends on the display, and how closely any given display hits the targets at the various saturation levels.

Do you have any insight on how one can correct that funky red saturation-luminance response that I showed in the bottom two graphs in my message above? Here they are again for reference. First is default; second has Red Y lowered.





The bottom curve tracks more closely to the reference but is still too bright at 75% saturation levels and below.
post #1622 of 1936
Quote:
Originally Posted by PlasmaPZ80U View Post

Do you mean 100% saturation/75% stimulus or 75% saturation/100% stimulus? I believe 100% saturation/75% stimulus is better than 100% saturation/100% stimulus since 75% stimulus produces about 50% light output, which is closer to most content than 100% light output.

That's probably what I meant. Just that we dont' look at colors at 100% saturation all the time or even most of the time when we watch TV?


bob
post #1623 of 1936
Thread Starter 
Quote:
Originally Posted by tqn View Post

Do you have any insight on how one can correct that funky red saturation-luminance response that I showed in the bottom two graphs in my message above? Here they are again for reference. First is default; second has Red Y lowered.





The bottom curve tracks more closely to the reference but is still too bright at 75% saturation levels and below.

You can just lower red brightness more, but since the line isn't straight, any adjustments will have non-linear results.
post #1624 of 1936
Quote:
Originally Posted by TomHuffman View Post

You can just lower red brightness more, but since the line isn't straight, any adjustments will have non-linear results.

That sucks. Seems I'll never be able to get rid of the reddish skin tones on my Samsung plasma then unless I make big compromises elsewhere. Perhaps the evolution of CMS should include controls for making adjustments to luminance vs. saturation.
post #1625 of 1936
Quote:
Originally Posted by tqn View Post

That sucks. Seems I'll never be able to get rid of the reddish skin tones on my Samsung plasma then unless I make big compromises elsewhere. Perhaps the evolution of CMS should include controls for making adjustments to luminance vs. saturation.

It already exists, it is called a Lumagen RadianceXE...
post #1626 of 1936
Quote:
Originally Posted by Joelc View Post

It already exists, it is called a Lumagen RadianceXE...

Sweet. Now I just need to sell my TV...and my audio system...to pay for it.

Any chance of that tech being built into a TV's CMS?
post #1627 of 1936
Thread Starter 
Quote:
Originally Posted by tqn View Post

That sucks. Seems I'll never be able to get rid of the reddish skin tones on my Samsung plasma then unless I make big compromises elsewhere. Perhaps the evolution of CMS should include controls for making adjustments to luminance vs. saturation.

Not sure I understand. You can make independent saturation and luminance adjustments with the Samsung CMS. What you can't do is make independent adjustments at different levels of saturation (25%, 50%, etc.) or amplitude. There is no commercially available product that I am aware of that offers this functionality.
post #1628 of 1936
Quote:
Originally Posted by TomHuffman View Post

Not sure I understand. You can make independent saturation and luminance adjustments with the Samsung CMS. What you can't do is make independent adjustments at different levels of saturation (25%, 50%, etc.) or amplitude. There is no commercially available product that I am aware of that offers this functionality.

Yes, I am looking to somehow, either directly or indirectly, make those independent adjustments at different levels of saturation. As it stands now, the Samsung CMS will allow me bring Red brightness down to the correct level ONLY at 100% saturation, leaving the 25/50/75 too bright. I believe that is why regardless of how hard I try to calibrate this display, I always see reddish skin tones.

I could bring the red brightness @ 100% saturation to well below reference to help bring down the curve at 50/75% saturation levels, but that will compromise deep reds, while still not helping at the 25% saturation.
post #1629 of 1936
Quote:
Originally Posted by tqn View Post

Yes, I am looking to somehow, either directly or indirectly, make those independent adjustments at different levels of saturation. As it stands now, the Samsung CMS will allow me bring Red brightness down to the correct level ONLY at 100% saturation, leaving the 25/50/75 too bright. I believe that is why regardless of how hard I try to calibrate this display, I always see reddish skin tones.

I could bring the red brightness @ 100% saturation to well below reference to help bring down the curve at 50/75% saturation levels, but that will compromise deep reds, while still not helping at the 25% saturation.

Try the Bruce Linbloom method for the brightness of red and hue of yellow. I used it simply for color/tint but I'm sure it can be used with the CMS as well.

http://www.avsforum.com/avs-vb/showt...6#post18476166
post #1630 of 1936
Forgive me if this has been asked before.

Whenever I use to meter to set color and tint, the pic just seems a little more drab, which is probably because I come up with a slightly lower color setting than I would with the filters (Color 0 and Tint 8 with meter/Color 3 and Tint 11 with 709 disc and blue only mode).

Is the meter the definitive way to adjust, and it's prob that I'm used to over saturated colors?

Calman and Chroma5

fL---100%W----100%R
x---0.3135---0.6442
y---0.3279---0.3150
Y---40.1908---8.4599

21% of 40.1908 is 8.44

Just making sure Im not missing something, thanks.
post #1631 of 1936
This is a little hard to describe, but I've been mulling this over for awhile. So, I'll give it a try.

All within Rec709 specifications (say). Just talking about one color (red) at this time, but it applies to all of them.

The given: The red Y value at 100% saturation should be 21% of 100% white Y.

The question: What should the red Y value be at 75%, 50%, and 25% red saturation? It seems to me that each color's Y value is like a tent pole and the white Y value is the center pole at D65. Looking at it from the side, the red pole (Y) is 21% of the center pole (White/D65). As the spots for lesser amounts of red saturation proceed towards D65 why doesn't the proper Y value go up so that it is linear from the starting point 100% red to 0% red (100% white)?

It just doesn't make mathematical sense that red Y stays at 21% of white Y as the saturation of red progresses from 100% ->75% ->50% ->25% ->10% ->5% ->4% ->3%, etc. all the way to 0%, only to suddenly shoot up instantaneously to 100% white Y.

I guess another way to ask this if this isn't clear, is to point out that there is a straight line from white to each color's Rec709 spot on the 2D CIE chart. What does this line look like from the "side" where vertical relationships (aka Y values) can be seen? Is it linear, or is there some other function? It just can't be flat (21%); that would be too weird as it approaches white and approaches 0% red saturation.

Make sense?
post #1632 of 1936
Thread Starter 
Rec. 709 is a specification for a full gamut of color and as such it is defined as only the outer limits of that gamut. Thus, within Rec. 709, I don't really think that less than full saturation has much meaning.

However, all else remaining equal, as you move a color towards the white point, it necessarily becomes brighter.

R100% G50% B50% (desaturated red) is brighter than R100% G0% B0% (full red).

Quote:
Originally Posted by kjgarrison View Post

This is a little hard to describe, but I've been mulling this over for awhile. So, I'll give it a try.

All within Rec709 specifications (say). Just talking about one color (red) at this time, but it applies to all of them.

The given: The red Y value at 100% saturation should be 21% of 100% white Y.

The question: What should the red Y value be at 75%, 50%, and 25% red saturation? It seems to me that each color's Y value is like a tent pole and the white Y value is the center pole at D65. Looking at it from the side, the red pole (Y) is 21% of the center pole (White/D65). As the spots for lesser amounts of red saturation proceed towards D65 why doesn't the proper Y value go up so that it is linear from the starting point 100% red to 0% red (100% white)?

It just doesn't make mathematical sense that red Y stays at 21% of white Y as the saturation of red progresses from 100% ->75% ->50% ->25% ->10% ->5% ->4% ->3%, etc. all the way to 0%, only to suddenly shoot up instantaneously to 100% white Y.

I guess another way to ask this if this isn't clear, is to point out that there is a straight line from white to each color's Rec709 spot on the 2D CIE chart. What does this line look like from the "side" where vertical relationships (aka Y values) can be seen? Is it linear, or is there some other function? It just can't be flat (21%); that would be too weird as it approaches white and approaches 0% red saturation.

Make sense?
post #1633 of 1936
Thanks for the reply Tom. You were who I was hoping for an answer from. It seems that you are agreeing with what I am saying.

Your example confused me though (not that hard to do.) As you move along the line from Rec 709 red point toward D65 (increasingly desaturated), why would the percentages of Green and Blue increase, and why would the percentage of Red stay the same? I would think 50% red would be R50% G0% B0%. No?

Isn't this concept useful when you happen to have a TV that doesn't have all the colors on their Rec 709 spots? I downloaded a spreadsheet called Gamut, Saturation, Brightness, dE Chart from someplace, and I was recently looking at it. The target Y values for all colors remained basically unchanged for all saturations. I believe you and I have just agreed that they should go up, and significantly so.

Color HCFR, for one that I know of, has 75%, 50%, and 25% test windows. I think I've seen somebody suggest using 75% to do calibration adjustments. I'm thinking that if you use the same percentage of White Y as the target for 75% Red Y that you use for 100% Red Y (21%) the colors would look dull. If the relationship is linear, 75% Red Y value would be 1/3 of the difference between White Y and 100% Red Y [((100-21)/3) + 21]. This comes out to 47.3%

At 50% Red, it's Y value should be a little over 60% of White Y. Again if this is linear. It could be geometric. I don't know.

Make sense?


Quote:
Originally Posted by TomHuffman View Post

Rec. 709 is a specification for a full gamut of color and as such it is defined as only the outer limits of that gamut. Thus, within Rec. 709, I don't really think that less than full saturation has much meaning.

However, all else remaining equal, as you move a color towards the white point, it necessarily becomes brighter.

R100% G50% B50% (desaturated red) is brighter than R100% G0% B0% (full red).
post #1634 of 1936
Quote:
Originally Posted by kjgarrison View Post

As you move along the line from Rec 709 red point toward D65 (increasingly desaturated), why would the percentages of Green and Blue increase, and why would the percentage of Red stay the same? I would think 50% red would be R50% G0% B0%. No?

No.

You're confusing saturation and relative brightness. Note that brightness (lightness, luma, luminance) is the unplotted z (or Y) axis of a chromaticity chart.

From the first post:
Quote:
Originally Posted by TomHuffman View Post

Terminology
  • xyY - A common method for precisely measuring color performance. x and y are the coordinates that plot out a color on the triangular CIE chromaticity chart mentioned above. This graphically represents the established definitions of the color spectrum. Y is the brightness of the color. This is not plotted by the xy coordinates.
  • Saturation - the colorfulness of the color relative to its own brightness. A color's saturation is displayed on the CIE chart as the distance from the white point. Add saturation to a color and it will begin to appear excessively deep and rich-red becomes crimson. Undersaturate a color and it will begin to appear as a less colorful version of a similar brightness--red becomes pink.
  • Hue - the primary characteristic of color that allows us to distinguish one color from another. A color's hue is measured by its angle to the white point. When a color's hue is off, its appearance will seem contaminated by other colors. For example, red that is too yellowish will begin to seem orange. Blue that is too reddish will begin to appear purplish.
  • Brightness - the luminance of color. The brightness of color (or white) can be measured by a simple light meter.
post #1635 of 1936
Thread Starter 
Quote:
Originally Posted by kjgarrison View Post

As you move along the line from Rec 709 red point toward D65 (increasingly desaturated), why would the percentages of Green and Blue increase, and why would the percentage of Red stay the same? I would think 50% red would be R50% G0% B0%. No?

No, that would be a fully saturated, but dim, red. White is R100% G100% B100%.

Quote:
Originally Posted by kjgarrison View Post

Isn't this concept useful when you happen to have a TV that doesn't have all the colors on their Rec 709 spots? I downloaded a spreadsheet called Gamut, Saturation, Brightness, dE Chart from someplace, and I was recently looking at it. The target Y values for all colors remained basically unchanged for all saturations. I believe you and I have just agreed that they should go up, and significantly so.

For purposes of testing linear behavior at lower levels of saturation, it really doesn't matter what the brightness is. Many have used constant brightness for these tests, but that's just an optional convention.

Quote:
Originally Posted by kjgarrison View Post

I think I've seen somebody suggest using 75% to do calibration adjustments. I'm thinking that if you use the same percentage of White Y as the target for 75% Red Y that you use for 100% Red Y (21%) the colors would look dull.

Again, since we are only testing saturation, the brightness doesn't matter. Some people do this because by using a CMS to get accurate saturation at the Rec. 709 specified points results in desaturated performance for the rest of the spectrum. Using 75% saturation as a target may result in lower average dEs throughout the entire spectrum than you would get if you used the standard Rec. 709 points.
post #1636 of 1936
Quote:
Originally Posted by ElwayLite View Post

Forgive me if this has been asked before.

Whenever I use to meter to set color and tint, the pic just seems a little more drab, which is probably because I come up with a slightly lower color setting than I would with the filters (Color 0 and Tint 8 with meter/Color 3 and Tint 11 with 709 disc and blue only mode).

Is the meter the definitive way to adjust, and it's prob that I'm used to over saturated colors?

Calman and Chroma5

fL---100%W----100%R
x---0.3135---0.6442
y---0.3279---0.3150
Y---40.1908---8.4599

21% of 40.1908 is 8.44

Just making sure Im not missing something, thanks.

I think you are indeed "used" to oversaturated television colors... it's easy to get hooked on all those vibrant neon reds and greens.

When you look at the screen, think about the colors of the faces and flesh tones on the screen? Hold your own arm up (if you're caucasian) and think: "Does the skin on the screen look real, like mine... or deeper orange or red?"

Look at the leaves on the trees on the television, and look out your window on a sunny day... do the leaves on the screen appear a natural green, not overly saturated? Or do they appear neon green (unnatural?)

If you do a search on AVSforum for "steaming rat" method of tweaking your set, this might help... it helps me "calibrate" TV's for which I don't have my photometer...

Cheers!

Doc
post #1637 of 1936
I am a little embarrassed about the calibration target settings and I hope somebody can help me.
I have an EyeOne Display 2 with Basiccolor 4.1 software and I would like to calibrate my LCD display for general end-user type PC usage, like web browsing, video games, movies, etc...

I have to choose between Gamma 2.2 (or 2.22 -> which one is theoretically better?) and sRGB (close but not similar to x^2.2) tonal response curves.

The default profile in the Windows CMS settings is sRGB IEC61966-2.1, so it suggests to set the calibration target to sRGB because the theoretically perfect (Windows-)PC monitor should have sRGB characteristics.

But there is a lot of other things that suggests that I should choose 2.2.
- Some calibration softwares (like OneMatch) do not even offer the sRGB response curve as a target.
- Cheap monitors usually do not have this kind of settings but the more expensive ones offer some gamma settings like 1.8, 2.2, 2.3, but I never saw if any of them offer sRGB gamma. (If there is an sRGB mode, that stands for a D65 WP or sometimes for sRGB gamut correction, but gamma is independent...)
- I would use the same settings that artists/producers/developers/engineers use to see the same what they saw during their works...

It is not clear for me. For example:
- Do web designers use their monitors with sRGB response curves as they should?
- If they use gamma 2.2 then do they convert their final product with care about the fact that end-users (theoretically) will watch it on sRGB monitors?
- Or is it the plan that they work and publish their products with gamma 2.2 and I should watch it on an sRGB display and it will be perfect because they work in controlled environment and end-users watch it on brighter rooms than a studio (or my PC-room...)?

What about game studios? Do (PC) video game developers care about this? Do they use displays with Rec709 or sRGB characteristics, or do they calibrate their displays to gamma 2.2?

Rec709 has it's own tonal response curve. There is a solution to convert it for PC monitors (either sRGB or gamma 2.2). But do HDTVs has this transfer function in the practice or do they have a gamma about 2.2?

And the last one: Here is this number 1/0.45=2.22222˙. Which one is more theoretically accurate number: 2.2 or 2.22? I saw the 0.45 in Rec709 documents but that system has a different transfer function than old CRTs (the mother of the x^2.2), so...

Sorry, if it was too much hotchpotch for a day.
post #1638 of 1936
hey guys i just was wondering my denon789 colour space is set to ycrbr on the panasonis bluray i set it too auto it readS 4.2.2 YCRBR IS THAT BETTER THAN ycrbr 4.4.4 i was playing aviatar it looked great i can set it to any of this settings ycrbr4.4.4///ycrbr4.2.2// which is better?? i was reading 4.2.2 is and older from of hdmi the reciever does all colourspace but rgb enhanced clippes the whites and black levels
post #1639 of 1936
Thread Starter 
Quote:
Originally Posted by demoniacal 360 View Post

hey guys i just was wondering my denon789 colour space is set to ycrbr on the panasonis bluray i set it too auto it readS 4.2.2 YCRBR IS THAT BETTER THAN ycrbr 4.4.4 i was playing aviatar it looked great i can set it to any of this settings ycrbr4.4.4///ycrbr4.2.2// which is better?? i was reading 4.2.2 is and older from of hdmi the reciever does all colourspace but rgb enhanced clippes the whites and black levels

See this.

http://www.spearsandmunsil.com/artic...olorspace.html
post #1640 of 1936
Thread Starter 
Quote:
Originally Posted by janos666 View Post

I have to choose between Gamma 2.2 (or 2.22 -> which one is theoretically better?) and sRGB (close but not similar to x^2.2) tonal response curves.

The difference between 2.2 and 2.22 is so small I wouldn't worry about it. For example, for a monitor with 120 nits peak output, the difference between the two options at 10% stimulus will be

2.2: 0.757
2.22: 0.723

This is a negligible difference and probably within the repeatability tolerances of your probe.

I believe that 2.22 is the correct sRGB spec, but many people simply round it off to 2.2.
post #1641 of 1936
Quote:
Originally Posted by TomHuffman View Post

The difference between 2.2 and 2.22 is so small I wouldn't worry about it.

I know that it won't change anything in the real world. I am just wondering which one is the theoretically accurate value.

Quote:
Originally Posted by TomHuffman View Post

I believe that 2.22 is the correct sRGB spec, but many people simply round it off to 2.2.

This is false. sRGB has it's own tonal response curve:
Quote:


The overall gamma is approximately 2.2, consisting of a linear (gamma 1.0) section near black, and a non-linear section elsewhere involving a 2.4 exponent and a gamma (slope of log output versus log input) changing from 1.0 through about 2.3

It is clearly noticeable when I change my VGA LUTs on-the-fly between 2.2 and sRGB calibrations. But which one should I use...?
Most of the studios should follow the sRGB specifications but gamma 2.2 is a common calibration target. (Some popular calibration softwares do not even support a true sRGB calibration.) I think it is not always clear for the studios. How should I choose then? (I am using 2.2 now.)
post #1642 of 1936
Thread Starter 
Quote:
Originally Posted by janos666 View Post

This is false. sRGB has it's own tonal response curve.

What, exactly, is "false?" That sRGB is 2.22 or that some people round it off? Not clear that your crib from Wikipedia comments directly on either.

Quote:
Originally Posted by janos666 View Post

Most of the studios should follow the sRGB specifications but gamma 2.2 is a common calibration target.

Since sRGB was developed with viewing web pages on computer monitors in mind, it is not clear why you think that "Most of the studios should follow the sRGB specifications . . . ." The studios are much more concerned with home theater displays reproducing Blu-ray and DVD content.

The question as to the proper gamma for this has been hashed over here ad-nauseum. As Poyton points out, there is no universal standard currently followed for gamma, though there should be. He recommends 2.35. However, since telecine operators at the studios have not yet taken his advice, Blu-ray and DVD content is mastered on monitors using no official gamma response that I know of, though 2.2 is often cited.
post #1643 of 1936
Quote:
Originally Posted by TomHuffman View Post

What, exactly, is "false?" That sRGB is 2.22 or that some people round it off? Not clear that your crib from Wikipedia comments directly on either.

The quoted wikipedia paragraph says that the standard sRGB tonal response curve is not a simple y=x^c function (like gamma 2.22 or 2.2) but it is a complex curve (with linear and exponential sections).
And the difference is clearly noticeable when I change between them.

Quote:
Originally Posted by TomHuffman View Post

Since sRGB was developed with viewing web pages on computer monitors in mind, it is not clear why you think that "Most of the studios should follow the sRGB specifications . . . ." The studios are much more concerned with home theater displays reproducing Blu-ray and DVD content.

I mean game studios (PC games) here, not film studios. I know that Blu-Ray contents are made for Rec709 displays and that standard has it's own tonal response curve (which is not a simple y=x^2.2 and it isn't identical with the sRGB curve). sRGB is close to 2.2 but Rec709 is far away from that.
Rec709 is another issue. Somebody is already working on the solution for that problem (Blu-Ray movies on PC monitors...).

Quote:
Originally Posted by TomHuffman View Post

2.2 is often cited.

I could make a quick test today. I discovered that Source Engine 2007 v2 (PC games use that, like Half-Life 2) has some console commands to set custom levels and gamma settings for the renderer.
- I set the values to 0-255 and 2.2 and I repeatedly enabled and disabled this switch. Nothing happened.
- I set it to 2.22 and I could see a very slight difference (small, but real changes...)

So, it seems that Valve software uses gamma 2.2 and the difference between 2.2 and 2.22 is very small but not completely irrelevant in real world situations (at least with 8 bit output and rounding...).

I will calibrate my display with x^2.20 response curve in the future. (I used to do it with sRGB curve in the last few months.)
post #1644 of 1936
how would you try to improve gamma if you could change only those parameters ? (no direct gamma changing option)

RGB drives and cuts (gains/offsets)
all drvs/cuts
sub-brightness
color
contrast
tint

if its possible please give me your thoughs, how would you try to do that for these two cases:
1) black has excellent shadow details, brightness in bright parts is too bright
2) black has poor shadow details, brightness in bright parts is excellent

I have Panasonic PY8 plasma and I used spyder3tv colorimeter, first of all I equaled the level of RGB to D65.
My theory is that for too bright parts I guess I should lower "all drv" and to get more shadow detail I should increase "all cuts" but it seems it affects each other (at least "drives" for greyscale)

best what I could without losing details in black, was moving gamme from 1,98 to 2,11 (but still too bright), I would prefer even more than 2,2, any ideas what should I try ?

my measurements after simple calibration:








post #1645 of 1936
1) Try to decrease contrast and check if black level is still calibrated, if not then reajust it and go back and forth if needed and try to get a compromise to get a gamma as near as 2.22 for all IRE.

2) Try to increase brightness and check if white level is still calibrated, if not then reajust it and go back and forth and try to get a compromise to get a gamma as near as 2.22 for all IRE.


Your gamma seems pretty "flat" around 2.1 for all IRE, which is good, but what you could do is to "shift" your gamma up to 2.22 by adjusting the green offset and/or gain to get it closer to 2.22, which is equivalent to increase or decrease the contrast around 20 IRE (gain) and 80 IRE (offset). Then you'll have to reajust the blue and red offset/gain to reach D65 for all IRE.

I did that with my 42LG50 because the gamma was not flat (too high from 40 to 90 IRE). But it was easier because I have a 10-points white balance calibration option.
post #1646 of 1936
Quote:
Originally Posted by don_ View Post

how would you try to improve gamma if you could change only those parameters ? (no direct gamma changing option)

RGB drives and cuts (gains/offsets)
all drvs/cuts
sub-brightness
color
contrast
tint

if its possible please give me your thoughs, how would you try to do that for these two cases:
1) black has excellent shadow details, brightness in bright parts is too bright
2) black has poor shadow details, brightness in bright parts is excellent

I have Panasonic PY8 plasma and I used spyder3tv colorimeter, first of all I equaled the level of RGB to D65.
My theory is that for too bright parts I guess I should lower "all drv" and to get more shadow detail I should increase "all cuts" but it seems it affects each other (at least "drives" for greyscale)

best what I could without losing details in black, was moving gamme from 1,98 to 2,11 (but still too bright), I would prefer even more than 2,2, any ideas what should I try ?

my measurements after simple calibration:









Not possible without crushing black. Brightness should be set with a black clipping pattern (not a meter) and contrast can be lowered to raise high-end gamma but don't expect too much in terms of overall gamma. The main thing you can do to get decent gamma is choose the Movie or Cinema preset to calibrate off of.
post #1647 of 1936
thanks guys for your reply



yes, you are right, using only these limited options its just not possible to set up exactly picture as I want
I tried many settings in last days but finally I gave up
I little improved cinema mode + colour calibration, and thats all, picture quality before was good - there is little better, but always could be better

Quote:
Originally Posted by MoonRabbit79 View Post

1)

Your gamma seems pretty "flat" around 2.1 for all IRE, which is good, but what you could do is to "shift" your gamma up to 2.22 by adjusting the green offset and/or gain to get it closer to 2.22, which is equivalent to increase or decrease the contrast around 20 IRE (gain) and 80 IRE (offset). Then you'll have to reajust the blue and red offset/gain to reach D65 for all IRE.

hmm but wouldn't be this same thing like adjusting to D65 all R-G-B offsets/gains first and then changing "all offset/gains" ?
because if I move G like you said I have to readjust RB anyway after that
but I am not so sure is it really same thing
post #1648 of 1936
I notice you list all of the Epson Home Cinema series as having proper CMS except the Epson HC 8100.

I have an Epson Home Cinema 8100 (non-UB model)...does this model qualify?

Considering getting an EyeOne LT (Display2 w/o the software as I understand it) and Chromapure for calibration.

Do I have proper CMS? Will the Display2 on a tripod be okay for my front projection? Is there a trial version of Chromapure 1 or 2?

Thanks
post #1649 of 1936
thx!
post #1650 of 1936
Hello, I'm relatively new to calibration and was wondering if someone could suggest what I'm doing wrong. I'm using the i1 with hcfr on a jvc rs10. I'm basically looking to calibrate for greyscale, contrast, brightness, and trying to target gamma for 2.2.

I don't seem to have any trouble with greyscale, but brightness and gamma is a problem. I've set white level to the jvc default which gives me acceptable luminance. Then, following the objective black level setting procedure I display a 10 ire pattern (Tom's posted images) and adjust Y to .65% of Y at 100 IRE. I adjust for greyscale then do a measurement. Greyscale measures fine and luminance tracks the 2.22 curve. However, when I check the brightness setting against a pluge pattern (avshd basic settings), it turns out the brightness setting is set to about six clicks too low. When I view a video, there's a clear loss of detail in dark areas. The picture is clearly better with the brightness set using the subjective pluge pattern.

I then do a new measurement with the new brightness setting, greyscale is still good, but hcfr now averages 1.9 and gamma no longer tracks flat across the scale. It tracks linearly from 10 to 30% then starts to drop off, until at 90% the gamma reading is about 1.1.

So I seem to be in a situation where my settings measure well but the black level seems wrong. When black level is set using the pluge it looks better, but gives me a gamma that tracks to a non-linear lower gamma average.

I'm not sure if it's a factor or not but I'm calibrating against a computer source using kmplayer. I haven't been able to find postings from others with like circumstances.

Thanks in advance. Any help appreciated.
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