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Colorimeter spreadsheet for SpyderTV - Page 3

post #61 of 207
The S2xyY utility does not work with SpyderTV yet.

For now it will only work with the English version of OptiCAL V3 or Spyder2PRO V1 and V2.
post #62 of 207
Thread Starter 
I had requests for DVE support and PAL color space. They are in the newest copy at the top of the thread. Enjoy.
post #63 of 207
Thanks, much aprreciated. We will play with it in PAL territory and let you know. Now hopefully we get Derreckjsmith to support SpyderTV soon .....
post #64 of 207
Quote:
Originally Posted by rader View Post

I had requests for DVE support and PAL color space. They are in the newest copy at the top of the thread. Enjoy.

Pardon my ignorance, I have trouble understanding what one is supposed to do with the PAL Color space. I have DVE, PAL version. Where do I "tell" the spreadsheet that this is the case? I guess inserting the different values for IRE (by the way, you left %Stim for DVE, which I guess is a mistake) in the DVD sheet would work for NTSC.
post #65 of 207
Thread Starter 
Quote:
Originally Posted by gorman42 View Post

Pardon my ignorance, I have trouble understanding what one is supposed to do with the PAL Color space.

You don't want to mess around with your color decoder until you have grey scale dialed in. I did not include instructions for the color sheets because I could not find much info on calibrating color decoders.
What I did was use the 75% red, green, blue, cyan, magenta, and yellow patterns from DVE to take xyY measurements for each color. I then used the user menu color decoder controls to adjust the levels of each color according to the "%error relative to green" chart. With my display I cannot change the xy coordinates of the primaries and secondaries (or just don't know how) so I left those alone.
To be honest I am not even sure if the color decoder sheets (HD, PAL, NTSC) are correct or useful. It is done to the best of my present understanding. Use them at your own risk and make sure you have a way to go back to your previous settings.


Quote:
Originally Posted by gorman42 View Post

I have DVE, PAL version. Where do I "tell" the spreadsheet that this is the case? I guess inserting the different values for IRE (by the way, you left %Stim for DVE, which I guess is a mistake) in the DVD sheet would work for NTSC.

Use the DVE sheet. The DVE levels are %input for both PAL and NTSC. Avia is the only one that uses IRE patterns assuming the American NTSC 7.5IRE black level.
For DVE the patterns you want are title 14 chapters 2-7 and title 13 chapter 8 to measure black. Since they are full field patterns rather than window patterns I would recommend decreasing contrast from its normal level for the measurements.
post #66 of 207
hey rader thanks for the DVE update!!!! just a quick question regarding contrast & IRE set-up. If you lower contrast when using DVE, won't that throw off the grayscale calibration? also, i noticed you pointed out that you stated that when using Avia you want 7.5 IRE set-up, but what about DVE should i change my DVD IRE set-up to 0 IRE or leave it at 7.5?

thanks so much Rader & others on the forum!!!!
Carmine.
post #67 of 207
Thread Starter 
Quote:
Originally Posted by noizemaker View Post

If you lower contrast when using DVE, won't that throw off the grayscale calibration?

In the ideal case no. In reality, possibly yes. IMO, it is better than the alternative of pushing the display to clipping which will really throw off your greyscale/gamma cuve.
Another alternative is to use the black, 20%, 40%, 60%, 80% full field patterns and then use the 100% window pattern (Title 14, chapter 8?) that comes right after the 100% full field pattern.

Quote:
Originally Posted by noizemaker View Post

also, i noticed you pointed out that you stated that when using Avia you want 7.5 IRE set-up, but what about DVE should i change my DVD IRE set-up to 0 IRE or leave it at 7.5?

This is where it starts to get confusing. The use of IRE to describe the patterns in Avia has to do with the levels for each pattern on the disk, and is independent of the levels output by your player. For example, if you set your player to 0 IRE setup and then display the Avia 7.5IRE black field, your player will output 0 IRE. So set your player to whichever setting you want, calibrate contrast and brightness, and then take the measurements.
If you look at how IRE levels are converted to %input in the spreadsheet (starting at column B-56) it might make this a little more clear.
post #68 of 207
Quote:
Originally Posted by rader View Post

Since they are full field patterns rather than window patterns I would recommend decreasing contrast from its normal level for the measurements.

Is this true for plasma screens as well? And thanks for all the great help.

Btw, what you wrote means that greyscale calibration is independant of PAL, NTSC or HDTV colorspaces? Did I get this right?
post #69 of 207
Thanks so much Rader for the clarification. I really appreciate your hard work on the creation of this indispensable tool for working with a Spyder colorimeter!!!!

Thanks again.
Carmine.
post #70 of 207
Thread Starter 
Quote:
Originally Posted by gorman42 View Post

Is this true for plasma screens as well? And thanks for all the great help.

I was thinking of plasmas and CRTs in particular. I don't know about other display types.

Quote:
Originally Posted by gorman42 View Post

Btw, what you wrote means that greyscale calibration is independant of PAL, NTSC or HDTV colorspaces? Did I get this right?

Yes, all use D65 white point and 2.2 gamma.
post #71 of 207
Rader,

I'm glad you put the disclaimer regarding the color tab. After putting my numbers in I found that my green was way off the chart (x0.267,y.709)! This certainly scared me a bit! I'll ignore it for now. Btw, one of your references lists "Original NTSC Color space" with very similar coordinates to what I have. So perhaps that is what my Display uses??? (reference: forum wouldn't let me post the url but it was on the videoessentials site)

I don't really know what I'm doing but I also set up my color decoder. I got all the color bars to match using the following method (on my original Grand Wega I, yes I know it doesn't have very good black levels...).

Technique (with avia and provided blue,green and red filters):

1. Use the blue color bars and a blue filter to set SCOL (color gain control) and SHUE (hue center control),
2. use the Red bars and red filter to set RYR and RYB,
3. use the green bars and green filter to set the GYR and GYB (in the MCP-ADJ2 group on the GW1).

I actually did that first and then turned the red/green panels off to verify SCOL and SHUE, turned the blue/green panels off to verify RYR and RYB, and the red/blue panels off to verify GYR/GYB. They required slight changes with the panel on/off method, but you really need to know how to navigate once you turn panels off so be careful!!!

Verified everything with the AVIA color decoder screen and it looked great!

If anyone knows that this method is wrong (or better yet if it is correct!), please let me know.

Anyhow, thanks a million for the spreadsheet Rader, it was an invaluable tool for setting up my display with the Spyder2Pro. I was able to get my %error to below 10% from IRE20 on (with deltaE either 1 or 2 from IRE30 up).

Looks great!
Rod

P.S. I got really bad results with the sensor on the screen, moved it back about 8 inches and it seemed to work much better (LCD rear projector).
post #72 of 207
Quote:
Originally Posted by Gorman42 View Post

Btw, what you wrote means that greyscale calibration is independant of PAL, NTSC or HDTV colorspaces? Did I get this right?
Quote:
Originally Posted by rader View Post

Yes, all use D65 white point and 2.2 gamma.

This is not correct. Grayscale calibration for PAL, SMPTE-C (NTSC) and HDTV will be different. You cannot move the location of the primaries and maintain the same white point without changing the relative balance of the primaries. You must re-balance the primaries for each display standard.

Play around with the XYZ->RGB matrices on Bruce Lindbloom's site to see what I mean.

Later,
Bill
post #73 of 207
Thread Starter 
Yes I know. My only interest in the XYZ -> RGB conversion is to generate to relative RGB error graph and red/green/blue gamma curves to serve as a visual aid to help the user know which color needs to move. Regardless of which transform is used the relative error graph will converge to 0% error at D65, and so far I have not found any xy data set that will tell you to move a color in the wrong way regardless of which conversion matrix is used.
Previously I had the three different XYZ->RGB matrices in the spreadsheet but later cleaned up and left only the r709 one. Through experimentation I found there was not much difference in the gamma and relative RGB error graphs between any of them. Will the gamma and RGB error curves move slightly? Sure. Will it make it any more difficult to adjust your display to D65? No. But you don't have to take my word for it - anyone interested in experimenting with the different colorspace conversions can find the transform matrices here: http://www.brucelindbloom.com/index....YZ_Matrix.html
Just copy the XYZ to RGB matrix you want to use (PAL, SECAM, NTSC, etc) from the Bruce Lindbloom page into the cells in F56 through H58 on whichever spreadsheet tab you are using.
Lets also not forget that the primaries on the majority of consumer displays are no where close to any of the standard primaries and the blend to reach D65 will be different for each.
post #74 of 207
Now the $400 question... what would I be giving up by going the SpyderTV+rader's spreadsheet vs going with the SpyderTV Pro?

If the answer is "a big amount of time" and nothing else, I might live with it and $400 more in my pockets.
post #75 of 207
indeed what would be the real difference especially once derickjsmith supports spyderTV with his S2xyY utility???? I gues the wizards of SpyderTVPro. Anything else???
post #76 of 207
If there are no reliable readings for the black level or 10IRE...(and still visually the brightness seems to be adjusted correctly)....what would be the values to put in the sheet for those missing measurements....left open....zero ...or 0.313/0.329 ?
post #77 of 207
Quote:
Originally Posted by JGT View Post

indeed what would be the real difference especially once derickjsmith supports spyderTV with his S2xyY utility???? I gues the wizards of SpyderTVPro. Anything else???

Well... I hope somebody can answer the question.

It could be asked in a different way, since SpyderTV Pro isn't out yet: what could be missing from the SpyderTV+rader's spreadsheet that could be found in SpyderTV Pro?
post #78 of 207
Thread Starter 
Quote:
Originally Posted by Arno P View Post

If there are no reliable readings for the black level or 10IRE...(and still visually the brightness seems to be adjusted correctly)....what would be the values to put in the sheet for those missing measurements....left open....zero ...or 0.313/0.329 ?

I increase brightness, often by 10% or more until I can take reliable readings of at least the Y value. The SpyderTV /support menu simply will not read black or 10IRE on my display with brightness at it's normal level, even with a 9 second read time. This is really strange since brightness is set to the values the SpyderTV told me to set it to (which look great). This comes with the caveat that adjusting brightness may alter gamma or other parameters on your set. For the black measurement the xy values are not used in the spreadsheet, only Y. If you cannot measure Y for black then it is impossible to calculate gamma (see Umr's post a few pages back).
Another tip, it will be alot easier to take low level measurments using GetGrey or DVE since the 10% and 20% patterns on these disks are at a higher level than the 10IRE and 20IRE patterns on Avia.
post #79 of 207
Quote:
Originally Posted by rader View Post

Another tip, it will be alot easier to take low level measurments using GetGrey or DVE since the 10% and 20% patterns on these disks are at a higher level than the 10IRE and 20IRE patterns on DVE.

HUH?
post #80 of 207
O.K., I have been trying to get the gamma curve right on a Sharp LCD display and tried using Rader's spreadsheet for DVE but my calculations don't match the curves that come out on the spreadsheet ??
My manual calculations are per the attached pdf file but basically I'm taking the percent input (x) to the power of the gamma (y) that I want (in this case 2.2) to determine the light output percent of full output (100%).

For example, with 40% input and gamma=2.2, I get 13.3% (percent of full scale or 100% input).
When I plug this in the spreadsheet it comes up with a number like 18% light output=2.2 gamma ??

What am I missing ??

P.S. I'm using spyderTv with the support option and 9 second read time..

Todd

 

Gamma.pdf 249.0185546875k . file
post #81 of 207
Thread Starter 
Quote:
Originally Posted by noizemaker View Post

HUH?

Err.. I meant to say Avia in that last sentence. Avia levels are in IRE with black at 7.5 IRE, so the 10IRE pattern is equivalent to about a 2.7% pattern, and 20IRE is equivalent to about 13.5%.

Todd,
That PDF was an interesting read, thanks. The reason for the difference between what the spreadsheet reports and your hand calculation is that the spreadsheet uses the rec 709 transfer function instead of the simplified CRT gamma transfer function mentioned in the article. You can see how this is calculated by looking at how the target curve is generated in the spreadsheet. See umr's post a few pages back on why to use rec 709.
post #82 of 207
hey rader quick question. what are all the values below the gamma chart & how are the correctly used? i realize the left portion are the Ideal values, but how would i correctly interpret all the other values?

thanks so much.
Carmine.
post #83 of 207
Rader, there seems to be a difference in gamma results between measuring with avia (incl correction) or measuring with Finzel....am I mistaken...(or a wrong measurement on my side)?
post #84 of 207
Thread Starter 
noisemaker,
The values below the gamma chart are used to calculate the data for the graphs. There is not much reason to interpret them unless you want to understand how it works or verify my calculations (which I encourage ).
Arno,
Can you email me a copy of the spreadsheet with your data in it. It should not make that much of a difference whether you use Avia or Finzel. My email is listed on the first sheet.
post #85 of 207
hey rader, thanks for the reply pal. so, there is really no need for me to pay too much attention to REC 709 XYZ, McCamy's N, etc...?

thanks.
Carmine.
post #86 of 207
Quote:
Originally Posted by rader View Post

For the black measurement the xy values are not used in the spreadsheet, only Y. If you cannot measure Y for black then it is impossible to calculate gamma (see Umr's post a few pages back).

You are referring to Post #7 in this? If it is, then you are misinterpreting Jeff's statements. The issue Jeff was describing is that your calculations had previously assumed a true black (no light) black level, and that was materially impacting your overall calculated gamma. In reality, there are several viable alternatives for calculating gamma. Here are two:

1) Take a curve fit. In this case, you can ignore the linear tail when trying to match the measured curve to the ideal. What you do want here, though, is a sufficient population of measurement points to make your fit result more statistically significant. (This is what Gary was doing originally)

2) Measure point gammas. Given that you only have one unknown (gamma) for each measurement point, you can actually solve for gamma for each measurement point beyond the linear tail (there is no gamma factor inside the linear tail). This is essentially what you are doing now.

Neither of these methods equire there to be a black level (0%) reading to be valid. All that the black level provides is another data point. One would note, though, that using a regression esitmation technique, the error in white (high light output) will dominate the calculated gamma value given the absolute numbers involved (i.e., there is limited variation in absolute terms at low stimulus levels).

Later,
Bill
post #87 of 207
Thread Starter 
Thanks for the tip Bill - it would make things much easier if I figured out a way to calculate gamma without measuring black.
post #88 of 207
Is the gamma accurate in this? I put the same measured values into this spreadsheet and the resultant gamma was 2.45, but if I put them manually into ColorfactsPro I get about 2.1.

Can anyone verify either Colorfacts or this spreadsheets calculations are accurate?

TIA

Gary
post #89 of 207
I have similar experience ... in fact, I'm puzzled by the following equation which is widely used in the spreadsheet:-

measured value + 0.099/1.099

grateful if someone good at maths enlighten the crowd
post #90 of 207
Quote:
Originally Posted by Gary Lightfoot View Post

Is the gamma accurate in this? I put the same measured values into this spreadsheet and the resultant gamma was 2.45, but if I put them manually into ColorfactsPro I get about 2.1.

Can anyone verify either Colorfacts or this spreadsheets calculations are accurate?

Whoops! I honestly hope they are not wrong... I just spent two hours starting the calibration process...
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