Xrite Color Profiles ?

Started 10 months ago | Discussions thread
Jack Hogan Veteran Member • Posts: 8,008
DE76

Jack Hogan wrote:

dddduuuu wrote:

Iliah Borg wrote:

dddduuuu wrote:

Iliah Borg wrote:

dddduuuu wrote:

Brightness 50, Blacks 5, Contrast 50 and Curve Medium Cobtrast makes ACR pipeline true linear.

You got it exactly wrong.

Here is our artice that explains the issue https://www.rawdigger.com/howtouse/overriding-raw-converter-default-adjustments-settings

you've missed the main point.

Try your setting instead without modifying the dcp to make the embedded curve (0,0) (1,1) and prove the resulting numbers for G with gamma 1 form a linear progression, increasing 2x per stop.

If DCP-profile doesn't have ProfileToneCurve tag, ACR applies the default one

"

To embed a linear curve into an existing profile, I use a very fast, reliable, and simple method:

> exiftool -ProfileToneCurve="0 0 1 1" -o new.dcp old.dcp

"

Are you suggesting that a user does the above (as in my comment to the article)? If so, IMHO you should have explained it explicitly, starting with what is "linear profile" in your "Just reset, then select linear profile and PV2. "Zero" of some adjustments is set with non-zero value. Brightness 50, Blacks 5, Contrast 50 and Curve Medium Cobtrast makes ACR pipeline true linear" and how to make one.

Iliah, i've made some research to explain you more clearly what I mean.

I downloaded raw image of studio shot on Nikon 4DS with ColorChecker24 and made some measurements and calculations. You can examine that measurements by yourself.

Here some results:

1. Max DE with your settings for linear process (profile Adobe Standard, Process Version 2, Blacks 0, Brightness 0, Contrast 0, Curve Linear) is 11,06.

2. Max DE with Adobe Linear profile and default (non-zero) settings (profile Adobe Linear, Process Version 2, Blacks +5, Brightness +50, Contrast +25, Curve Medium Contrast) is 6.61. Colors of gray patches exactly the same as with previous settings. But color patches are more close to reference values.

3. I've made the most simple profile Adobe ColorMatrix with only four image-related tags ColorMatrix1, ColorMatrix2, DefaultBlackRender and ProfileToneCurve. Only 22 numbers. Settings: Process Version 2, Blacks +5, Brightness +50, Contrast +25, Curve Medium Contrast. Max DE 6.52, very close to Adobe Linear. Just interesting.

Those are fairly bad. With a linear rendition you should be getting about half that

https://www.strollswithmydog.com/open-raspberry-pi-high-quality-camera-raw/

From the raw file for the Nikon 4DS above, not necessarily representative but SMI 88 (pretty good) as follows:

Left deltaE2000, right deltaE76

This is what can be expected from a 'good' sensor and a linear matrix profile.

Jack

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