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Is the calibration curve that DisplayCAL profile loader loads into the VCGT from the ICC file used for grey correction/calibration only? Take a look at the attached ICM profile; it only has a tone response curve, not a calibration curve.
- How is a tone response curve different from a calibration curve?
- Is the tone response curve loaded into the VCGT like a calibration curve?
- What does a tone response curve do, and how is it used?
- Since this ICC profile doesn’t have a calibration curve, wouldn’t using Windows Color Management to load it instead of DisplayCAL profile loader make no difference?
VCGT = (grey/gamma) calibration, applied system wide
gamut boundaries (XYZLUT or matrix with primaries) + TRC = info needed by ICC based color mangement
As explained before rtings profiles have no calibration, they have no VCGT, there is no info to load into GPU LUT.
To make a LUT3D open LUT3D maker, set as source profile the colospace to simulate and as destination profile a profile taht describes diplay at ITS CURRENT STATE (all OSD settings on THAT preset), choose suitable LUT3D file format and generare it.
You would need a meter. It measures the patches in the lut3d setup. The profile was made with a good instrument. The low 5% of the display calibrated has r g b seperation. You can check out calman 3.1 on cnet and do visual color calibration and not use color management for watching tv or movies. You could see the color of grey in the dark brightness test. lagoom has a test too. http://www.lagom.nl/lcd-test/black.php . This part of the chart is mostly your black level and 5% white balance. 10% is above 16 rgb.
The tone curve is not the gamma like 1886. Its native color is 1886. The gamma is what the default of the monitor probably srgb almost. You need to check rtings calibration settings to know. Calibraton curve is the white balance correction which sets the gamma. The lut is linear and not calibrated. It is fine though to get color saturation right by eye. Google around for by eye calibration or cheap calibration. For 1 year I used a camera to calibrate till I saved for a meter.
Screens change between builds and over time especially in the low end. The high end gets lower lumans over a long time. It did with ccfl screens. Not sure with white led or newer screens. You can watch the rtings accelerated longetivity test to look for patterns https://www.rtings.com/tv/tests/longevity-test . I have the v555-j01 . Not at all like it says it is.
I guess I am wrong about needing a meter to make a 3dlut from a profile. sorry.
- Since this ICC profile doesn’t have a calibration curve, wouldn’t using Windows Color Management to load it instead of DisplayCAL profile loader make no difference?
Can someone answer this for me please?
It is complicated. Windows color management loads 8bit resolution of video card look up tables. You will not get banding useing WCM with no calibration curve. The apps are what read color correction and load it. Windows does not really load color correction. It loads white balance correction in 8 bit rgb. Your video card loads the lut. WCM or displaycal profile loader can feed it.
I think it makes no difference if the profile has no calibration curves. My opinion is Life is easier with Display Cal profile loader. It has more options and is better.
It is complicated. Windows color management loads 8bit resolution of video card look up tables. You will not get banding useing WCM with no calibration curve. The apps are what read color correction and load it. Windows does not really load color correction. It loads white balance correction in 8 bit rgb. Your video card loads the lut. WCM or displaycal profile loader can feed it.
I think it makes no difference if the profile has no calibration curves. My opinion is Life is easier with Display Cal profile loader. It has more options and is better.
I see, thank you.
- Since this ICC profile doesn’t have a calibration curve, wouldn’t using Windows Color Management to load it instead of DisplayCAL profile loader make no difference?
Can someone answer this for me please?
It is complicated. Windows color management loads 8bit resolution of video card look up tables. You will not get banding useing WCM with no calibration curve. The apps are what read color correction and load it. Windows does not really load color correction. It loads white balance correction in 8 bit rgb. Your video card loads the lut. WCM or displaycal profile loader can feed it.
I think it makes no difference if the profile has no calibration curves. My opinion is Life is easier with Display Cal profile loader. It has more options and is better.
No calibration means no calibration. Windows at best may reset to linear VCGT where input=output, which shoud show no banding due to GPU calibration.
Of course if you apply a new profile with VGCT calibration it will truncate until you switch to DisplayCAL’s & reboot.VCGT = (grey/gamma) calibration, applied system wide
gamut boundaries (XYZLUT or matrix with primaries) + TRC = info needed by ICC based color mangement
As explained before rtings profiles have no calibration, they have no VCGT, there is no info to load into GPU LUT.
I looked at the calibration curves stored within an ICC file, noticing three separate curves – one for R, G, and B. Am I right in understanding that these calibration curves are essentially individual lookup tables (one for each color channel)? Also, could you explain ‘grey calibration’? Does it involve adjusting/correcting various shades of grey? If so, how do the three lookup tables contribute to this process? Lastly, you mention that ICC-based color management requires gamut boundaries and TRC. I presume the gamut boundaries inform applications about the display’s color reproduction capabilities, allowing them to make corrections. Could you elaborate on how TRC specifically is used within color management?
VCGT = (grey/gamma) calibration, applied system wide
gamut boundaries (XYZLUT or matrix with primaries) + TRC = info needed by ICC based color mangement
As explained before rtings profiles have no calibration, they have no VCGT, there is no info to load into GPU LUT.
I looked at the calibration curves stored within an ICC file, noticing three separate curves – one for R, G, and B. Am I right in understanding that these calibration curves are essentially individual lookup tables (one for each color channel)?
Yes, LUT 1D x 3
Also, could you explain ‘grey calibration’? Does it involve adjusting/correcting various shades of grey?
Correct color of each grey and gamma. On 8bit to 8bit there are going to be jumps because the only biyective combination is input=output. On 16bit VCGT + high bitdepth LUT GPU to 8bit, dithering will smooth and be bandless
If so, how do the three lookup tables contribute to this process?
Corrects grey. RGB 128 128 128 shoulg be for example 127.5 126.25 128.75 (VCGT stored as 18bit, with “decimals”)
Lastly, you mention that ICC-based color management requires gamut boundaries and TRC. I presume the gamut boundaries inform applications about the display’s color reproduction capabilities, allowing them to make corrections. Could you elaborate on how TRC specifically is used within color management?
TRC is measured “gamma” for each channel. Let’s suppose that you calibrate to gamma 2.4, ICC profile stores gamma 2.4 and open an sRGB tagged image in Photoshop. Photoshop will reencode RGB numebrs in image (encoded in sRGB) o other DIFFERNT values so in your display 2.4 image is show as if display were sRGB with sRGB TRC.
Photoshop and other apps may have issues with rounding errors (8bit to 8bit) unless they have dithering (LR, C1), hence “the ideal” if you have no reliable HW calibration is a GPU with dithered outputs (like an AMD), profile created and loaded by DisplayCAL (16bit loader) and a profile type with 3 equal TRC. This way color corrections mabe by Photshop will be extremely simplifies and less prone to rounding errors.
A rtings profile with no calibration and 3 different TRC are likely to cause these issues and of course games or other non color managed apps won’t have any kind of grey correction
