20
votes
Raw photo for scientific purpose. How to set white reference to defined numeric L*a*b value?
Sounds a bit iffy to me... A card, by itself, DOESN'T have a fixed L*a*b* colour - that's a product of the reflectivity of the card at different wavelengths and the intensity and wavelength ...
- 3,003
11
votes
Accepted
Raw photo for scientific purpose. How to set white reference to defined numeric L*a*b value?
This frequently comes up in photographic reproduction jobs where one is trying to closely approximate some other object such as a painting antique drawing. This cannot be done with typical photographs ...
- 1,207
3
votes
Accepted
Change color of an object in Lab that does not share the same channel
Let's say I want to change this image, "Still, by Sara Dorweiler via Unsplash" to make the leaf blue. Let's start with an info point.
So we have -12, 20. For blue it should be something fairly close ...
- 2,447
3
votes
Accepted
Does Lab color mode in Photoshop give some advantages over Adobe RGB on skin retouching?
Alright well AdobeRGB vs Lab in this case isn't really the benefit or concern so you're kind of asking the wrong question. There's really two questions:
Do the channels available in Lab make up for ...
- 2,447
3
votes
Accepted
Which rendering intent to use when saving CIE-Lab values in Silverfast
I don't think that it has anything to do with using the CIE-Lab colour space, and you should only use absolute colorimetric rendering intent if you are doing colour proofing. Relative (or perceptual) ...
- 1,037
3
votes
Accepted
Do CEIL LAB images look really the same on all monitors?
No. CIELAB images are just as subject to different displays as RGB images. As you note CIELAB is converted to RGB in order to be displayed since displays do not use CIELAB. However, if displays are ...
- 1,207
2
votes
Accepted
In Photoshop, how to get the histogram and statistics of CIELab values
Photoshop's histogram provides means(averages) for Lightness, a, and b.
They are not normalized but shown in the LAB PCS space used by ICC profiles which go from 0 to 255 in unsigned, 8 bit values.
...
- 1,207
2
votes
Accepted
Why does temperature in Lightroom go from blue to yellow instead of orange to bright blue?
It's not exactly using the a*/b* CIELAB channels/values; even though that is what it looks like.
When you set the temp towards the blue side of the slider you are telling the program that the light ...
- 12.6k
2
votes
Lab to RGB conversion, and RGB colour space default
Programs such as Photoshop allow you to change to a variety of color spaces like sRGB, Colormatch RGB, Adobe RGB, and ProPhoto RGB (listed in order from smaller to widest color gamut). Does the image ...
- 2,663
1
vote
Lab to RGB conversion, and RGB colour space default
No. It is not possible. The sRGB color gamut can’t be made wider. Making it wider makes it something else, Adobe RGB for example.
The reason to use a Lab based workflow is to reduce the effects of ...
- 4,815
1
vote
How do color values change mathematically as you change temperature and tint?
Adobe actually describes extremely well their white balancing process in the Digital Negative (DNG) Specification, specifically in Chapter 6 Mapping Camera Color Space to CIE XYZ Space.
The process is ...
- 850
1
vote
Accepted
How do color values change mathematically as you change temperature and tint?
This is a more tricky question that you might think.
First, the RGB value that you see with your eyes on the screen are the result of an operation on the processed output from Lightroom, that is ...
- 361
1
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Why does temperature in Lightroom go from blue to yellow instead of orange to bright blue?
If you look at my related answer here: https://photo.stackexchange.com/a/122262/20809, the White Balance process of Adobe Photography products, i.e. Adobe Lightroom and Camera Raw, is outlined.
As for ...
- 850
1
vote
How to change saturation on a curve in RGB mode, in Photoshop?
What you describe, editing saturation curves in RGB mode, may not be possible. However, it is possible to enhance a few colors in an image with the curves tool.
The way I think of saturation, which ...
- 26.8k
1
vote
Which rendering intent to use when saving CIE-Lab values in Silverfast
Lab* = (100,0,20) does not make sense, as L*=100 is maximum intensity, and thus it is white. If it were not white (has some color cast), you could additively add another complementary color, and then ...
- 399
1
vote
Accepted
Photoshop CIELab values: What does my display show after color management?
Assuming you properly calibrated and profiled the monitor to D65 with the computer's GPU set to output to a D65 monitor it should.
Photoshop doesn't really take your monitor profile into account. But ...
- 173k
1
vote
Accepted
SilverFast CIELab: What illuminant and observer is assumed?
Whenever an illuminant is not specified, assume it's D50 as that is the standard the ICC adapts its profiles to even if the device illuminant differs. For instance a Lab reading in a Photoshop image ...
- 1,207
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