Comments on: Applied Color Theory in September

By: Dan Margulis

Dan Margulis — Mon, 08 Jun 2015 14:00:02 +0000

Optimo, different RGBs have different gamuts because our language is not precise enough. If you say “255r0g0b” I know that it is “red”, but I do not know what “red” means specifically. If you say 54L81a70b, that is unambiguous, we know exactly what red is being referred to, which happens to be the same as 255r0g0b in sRGB. But in Adobe RGB the equivalent is 63L80a78b, and every other RGB has a different definition as well.

By: OPTIMO

OPTIMO — Wed, 20 May 2015 23:35:33 +0000

Thanks, your word remind me of what you told me early in the book, blue channel only compose one percent for the whole contrast. Most of my troubbles occur in bule channel. And there is another tiny question, why different RGBs have different gamut? They are all have 256 in each channel.

By: Dan Margulis

Dan Margulis — Wed, 20 May 2015 14:09:12 +0000

Optimo, I would not worry too much about a bad blue channel. We cannot see detail in yellows that bright. If you said that the flowers were magenta rather than yellow, and that the green channel was very bad, this would be much more serious and you would need to find a solution. But a bright yellow flower is different, we can appreciate its color but not so much its detail.

By: OPTIMO

OPTIMO — Thu, 14 May 2015 14:54:14 +0000

Thank you very much for your patience. In camera Raw, the blue channel of a yellow follow sometimes become totally black. I try to get it back but in vain. I do not know it is normal or not, for I lack the experience in dealing with raw image. Your book is very helpful to me, it is time for me to read it again and again.

By: Dan Margulis

Dan Margulis — Wed, 13 May 2015 13:13:17 +0000

Optimo,

A camera cannot capture something that is out of the camera’s own gamut. So there is an incorrect usage of Camera Raw. In your first message you indicate that you did something in LAB that destroyed the image by forcing colors out of output gamut. Now in this second message you say ythe same thing is occurring in Camera Raw. I cannot guess at what has happened because there are thousands of ways to drive colors out of gamut in LAB and thousands of other ways to do it in Camera Raw. All I can say is to repeat the advice of the book: it is the user’s responsibility to take care that it does not happen.

By: OPTIMO

OPTIMO — Sat, 02 May 2015 08:04:02 +0000

When I shoot something with bright colour, the photo I take has already gone over the RGB gamut. What should I do? Should I force it to nomal in Camera Raw by adjusting “black” and “white” or set a special white balance to achieve complete RGB channels ? And will an image of 16 bit help to solve this and control noise?

By: Dan Margulis

Dan Margulis — Sat, 25 Apr 2015 19:51:56 +0000

Optimo,

*In Camera Raw you move the Exposure slider to -2.00 and all shadow detail is destroyed. Are you wrong to use Camera Raw?

*You drive your car at 180 kph, and the police stop you and take you to jail. Are you wrong to drive the car?

If your RGB channels are plugging, it indicates that you have used LAB to try to force colors that are out of the RGB gamut. The book strongly cautions against doing that and to monitor the Info palette to make sure it does not happen.

By: OPTIMO

OPTIMO — Mon, 20 Apr 2015 10:30:38 +0000

After enhancing colour in LAB mode I usually find channels in RGB has been detroyed, being totally black. Am I wrong to use the tool?

By: yoann

yoann — Sun, 25 May 2014 06:39:27 +0000

Oh thank you Dan for these precious ideas.
I am not really looking for some recipes, more trying to find ways to simplify or go over some technicalities in order to focus on the artistic side.
I will definitely take a shot at all your books and i am sure they will stay on top of the pile of color correction for quiiite a while

By: Dan Margulis

Dan Margulis — Sat, 24 May 2014 23:24:22 +0000

Yoann,

If there were a recipe for “art” we could let a machine do it. It’s harder than standard color correction because of what you are producing is considered “art” and not “photography” then you aren’t limited by what the viewer might take to be realistic.

The PPW actions are valuable for this because they deliberately exaggerate effects. The idea is it’s easier to cut back on excessive color than it is to force color into a bland file. By the same token, however, it makes it easier to see where certain obviously exaggerated effects may nevertheless be artistically desirable.

I’d especially point out the options windows for the MMM and also the MMM + CB actions, which allow you to try and compare several different approaches. Also, if you are interested in counteracting the Helmholtz-Kohlrauch Effect, the H-K action’s options will permit that. (The action itself does the opposite, it caters to the effect by darkening neutrals, but you can configure it to do the opposite.)

For tricky moves in LAB, my book Photoshop LAB Color may be ten years old, but the “artistic” portions of it are not out of date.