I'm trying to adjust grayscale, gamma etc. on my TV it's a jvc-hd56fc97 (lcos) and have a few questions that might solve my issues with the blue drive having a big drop at 50-60 ire and other grayscale gamma issues.

My TV only has the following:

RGB drives in the service menu (adjustable from 0-255)
basic settings in the user menu (tint/color, brightness/contrast, sharpness, and adjustable iris.

No gamma controls or gains/cuts.



I can achieve a fairly balanced grayscale setting the drives either high low in the middle etc.

For example set the drives at r=165 g=140 b=127 or set them lower at say red=125 g=100 b=80 etc. etc.

I can not see any significant difference in grayscale tracking between 20 ire and 80 ire when I use the different settings, only a difference in luminance with the higher drive settings. I know I am missing something stupid I just can't figure it out.

How do I decide how high to set the drives? What should I be looking for? Is damage possible like in CRT technology? Etc. etc.

Thanks,
Justin

You didn't mention if you're trying to do this by eye or with equipment such as a colorimeter/spectroradiometer or optical comparator. If you have equipment, you should let it be your guide to achieving D65. If you're going by eye, I recommend using a gray ramp or step scale pattern so you can see what your changes are doing to the entire grayscale. Try to get the entire ramp/step pattern as color-free (no noticeable color tint, especially red or green, in any part of it) as you can.

Sorry, I am using a spyder2 meter and colorHCFR.

When you say achieve D65 are you saying to achieve a balanced grayscale of 6500? Which I can (fairly well) using many various different intesity settings for RGB and get them all within 10% of 6500.

I know I am missing something simple and have been reading as many threads as possible but have not been able to figure it out.

How high should I set the intesity of the drives?

Any sugestions to improve the tracking of the blue on my grayscale?

Improve gamma and deltaE?

Any overall sugestions?

Thanks,
Justin

D65 is the exact white point in CIE colorspace for SD/HD video standards, deltaE is the standard error measure from that target. It is near the 6500K color temperature line - which ranges from magenta thru white to green. Don't use 6500K charts as your calibration target- use the D65 targets.

If you have a RGB histogram in your software - just raise the RGB drives until the color clips. That is your maximum uncalibrated contrast limit for a 100% white - work backwards from there to D65. The RGB biases are for the dark blacks - the controls will interact so you need to play with the controls and get a feel for what they do, how they range, how they interact. If you are clipping either of these your gamma curves will be way off. That is the art of calibration - it is not a paint by number system.

D65 is the exact white point in CIE colorspace for SD/HD video standards, deltaE is the standard error measure from that target. It is near the 6500K color temperature line - which ranges from magenta thru white to green. Don't use 6500K charts as your calibration target- use the D65 targets.

I misspoke when I said 6500k color temperature line. I am using the D65 targets to calibrate grayscale. (Unless I am mistaken)

I understand the basics of deltaE and am trying to keep it under 4 from 20ire through 80ire but go far I am not having the best of luck.

If you have a RGB histogram in your software - just raise the RGB drives until the color clips. That is your maximum uncalibrated contrast limit for a 100% white - work backwards from there to D65.

My software colorHCFR does not have a RGB histogram that I am aware of. How can I tell when a color clips or the maximum contrast limit?

Do you mean to raise the RGB drives to I can no longer produce D65? Should this be done at 100 ire?


The RGB biases are for the dark blacks - the controls will interact so you need to play with the controls and get a feel for what they do, how they range, how they interact. If you are clipping either of these your gamma curves will be way off. That is the art of calibration - it is not a paint by number system.


My tv a jvc-hd56fc97 does not have rgb biases only rgb drives. So I am asking if there is a method or a technique I should use when only RGB drives are available?

Without cuts, you'll probably have to compromise more than usual. Start by getting your 100% white to D65. Then check the dark end by measuring a 30% gray pattern. You may have to lower your D65 target adjustment point to 80% or so to get the darker end of the scale closer if it isn't already. Use the ramp or step scale patterns to do a visual crosscheck. Keep in mind that getting dead-on D65 all across the scale can be tough even if your display has cuts as well as drives. You should get as close to D65 as you can, but I personally believe it's most important to get the whole scale as flat (close to the same color temp) as possible, even if you miss D65 by 200-300K.

Justin,

How are you progressing? I just got the same model and would like to try and calibrate my set. I will be using colorHCFR and the DPT 94. Any pointers?

thanks,

Mark

Mark,

My set seemed to have a dip in the blue around 40-60 ire. What I did to compensate was to raise brightness and contrast up about 10-15 clicks from where I had them to achieve a better gray scale at the expense of a smoother gamma curve. The problem is still there but I was able to get a deltaE of 4 or less from 20 ire to about 70-80 ire but my whites are probably slightly clipping and the blacks also are probably very slightly clipping.

I can write more later to explain better but I am off to the bars to meet some friends. I would also love to hear how your calibration went because I am still not happy, even though the picture looks great, I know I can improve on it and would love to exchange ideas and settings.

Justin

Justin,

I plan on starting tomorrow so tonight I wanted to set brightness, contrast, etc. It appears, though, using Digitial Vidoe Essentials that I'm not getting blacker than black. My DVD player is a toshiba 3109 that was able to pass btb on my previous TV. Any ideas?

My software colorHCFR does not have a RGB histogram that I am aware of. How can I tell when a color clips or the maximum contrast limit?

?

In ColorHCFR

Use the Luminance Histogram icon (gamma tracking), then right click the pattern and to select Red, Green, BLue and Logarithmic Mode (leave anything else at default), look to see which of all the colors dip DOWNWARDS - this will be your clipping color..

Justin,

I plan on starting tomorrow so tonight I wanted to set brightness, contrast, etc. It appears, though, using Digitial Vidoe Essentials that I'm not getting blacker than black. My DVD player is a toshiba 3109 that was able to pass btb on my previous TV. Any ideas?


I experienced the same thing.

Here's my attempt. How can I raise gamma without access to any gamma controls?

Here's my attempt. How can I raise gamma without access to any gamma controls?

try reducing contrast a click or two and rerun..

mskreis,

Are you using standard mode and have you tried to calibrate in theater pro mode?

try reducing contrast a click or two and rerun..

Thanks for the tip - I'll give it a try this weekend.

mskreis,

Are you using standard mode and have you tried to calibrate in theater pro mode?

Yes, I'm using standard mode. I have not tried theater pro.