New article on color management

Started Apr 26, 2013 | Discussions thread
Jack Hogan Veteran Member • Posts: 6,708
Re: Camera-->sRGB versus Camera-->ProPhoto-->sRGB

gollywop wrote:

As to a choice between the bottom two, each has its value (but there is no question about which is the easier to produce).

Good show Gollywop. This is the link to your flower dng file and this is the accompanying text:

"This file is underexposed about 1EV according to RawDigger.  It was shot with UniWB (hence the greenish tint).  A WhiBal card shot in the same light indicates a WB (for ACR) of 4900/3, and that is what I used for the image as posted.  It is also clear that the image as posted was cropped."

I've been thinking about the wild guesstimates during conversion mentioned earlier, and I've found that they can be really apparent.  Here is an example: note the clipping in the right petal in ProPhoto-->PP-->sRGB compared to sRGB-->PP (I know that GIF's are not ideal, but they make animation simple - hope it works).  Here are the Original TIFFs which are much better for comparison: ProPhoto , sRGB .

If the animation works the two images should alternate every 4 seconds

Perhaps the reason is that adaptive editing programs are a little more sophisiticated in dealing with boundary conditions than color space conversions/CMSs, which I assume blindly apply their formulas.  Here is the path that a color on that petal took in xyY space:

1. Opened NEF in CNX2 either in ProPhotoRGB and in sRGB
2. Changed Picture Control from Neutral to Landscape
3. Applied CEP3 Tonal Contrast at default values
4. Converted ProPhotoRGB image to sRGB

Path of sample color during processing

And here is another sample color from the left side of the flower: this one was luckier than the next.

More space waks

Here is a sample color's trip on the Blue Ball image with the purple shift going from ACR 6.7 Standard through CEP3 Tonal Contrast - this one was doomed from the start.  It seems to me that the hue shift was introduced by ACR when it applied the color spaces originally.

It seems to me that despite the fact that I selected 'perceptual' intent, when programs/CMMs convert to sRGB they simply bring whoever is out to left field back to the edge.  While instead if you are working within the smaller space to start with, the editing programs are a bit more mindful about not hitting the ceiling.  What do you guys think?


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