... but the facts of arithmetic are that if you edit images in 8-bit mode, they become less and less a representation of the subject, and more and more a collection of mathematical/sampling artifacts that loosely resemble the subject.
John,
This is not a Dan Margulis discussion. So far no one advocated for 8 bit only. The question was about how to deal with a given 8 bit file and in particular
when to introduce 16 bit.
Here’s a numerical example:
1.) Create a new file in 8 bit mode (sRGB)
2.) Fill this background layer with one single color of RGB= 200, 100, 100.
Option (A.)
3.)
Change to 16 bit mode.The ‘16 bit’ readings from the info pallet should indicate: 25700, 12850, 12850
4.) Add a New layer to fill it with another color of RGB= 201, 101, 101
The ‘16 bit’ readings from the info pallet should indicate: 25829, 12979, 12979
5.) Set this layer to 50% Opacity.
6.) Flatten the layers
The final ‘16 bit’ readings from the info pallet should indicate: 25765, 12915, 12915
Option (B.)
3.) Add a New layer to fill it with another color of RGB= 201, 101, 101
4.) Set this layer to 50% Opacity.
5.)
Change to 16 bit mode.6.) Flatten the layers
The final ‘16 bit’ readings from the info pallet should indicate: 25765, 12915, 12915
Both options produce the same result. The final numbers represent the arithmetic average of both original colors. The resulting numbers are really high bit as they don’t have an integer 8-bit-equivalent anymore.
It was not necessary to create the colors in 16 bit mode.
The only important thing was to have 16 bit precision in place just when the layers are flattened. Needless to say that many more examples can be created with Levels, Curves, etc…
In summmary: You could take the 8 bit file, add all adjust layers needed (for Smoothing, Sharpening, Levels, Curves, etc.), save it as psd file…- …and when you then change to 16 bit mode in order to flatten the layers, it yields real high bit precision.
Peter
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