New article on color management

Started Apr 26, 2013 | Discussions thread
Detail Man
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Re: Does Melissa "Gloss Over" Image Noise ?
In reply to Jeff Schewe, Apr 27, 2013

Jeff Schewe wrote:

Detail Man wrote:

So, the only impact of the sRGB tone curve would be color readouts in 0-100% (which don't relate to 0-255) and the way the levels are displayed on the histogram.

So, the gamma-correction function that is applied to the Adobe CR/LR preview display-screen corresponds to whatever particular color-space that the OS recognized "system display profile" is ?

If that is the case, then it would seem that a system having an sRGB color-space "system display profile" would not be able to accurately reflect the gamma-correction function that results in cases when the output images are rendered in ProPhoto RGB or Adobe RGB 1998 color-spaces ?

Don't assume the display profile is sRGB...my NEC displays are 98% of Adobe RGB...

Right.

... also don't get too wrapped up in the whole display/output profile gamma. They are two different things.

Could you explain that further ? It seems like you have stated that the gamma-correction funtion that is applied to the CR/LR (preview) display is solely determined by the particular (OS recognized) color-space that the (utilized) system output profile exists as a set of "tweaks" to. Right ?

The only place where the display gamma would have any impact is if an application isn't color managed. There the differences in the display gamma and output gamma would have an impact since sRGB/Adobe RGB are both nominally 2.2 (sRGB has a toe tweak) and ProPhoto RGB which is gamma 1.8.

But, as long as viewing apps are color managed, the final appearance on-screen should be accurately transformed from the image color space/gamma to the display space/gamma.

I recognize that the common (and most likely case) is that a user would be processing an image-file for display on the very same system that they are performing the image processing on.

My thought, however, is that such is not always and invariably the case - and that it would be useful if CR/LR preview display was capable of using the particular gamma-correction function directly associated with whatever color-space(s) they may be choosing to render in and save to.

Otherwise, the previewing of low-level image-noise is locked into whatever particular color-space that the display associated with the system being used to do the processing happens to be.

That would be fine if one has a wider gamut display and might choose to (also) alternately restrict the (OS recognized system) color-space to a narrower gamut color-space for rendering in and saving to.

However, if one is performing the processing/editing on a system having a narrow gamut (OS recognized) system color-space (only), but would like to (also) render in and save to wider gamut color-spaces for display on other systems, then they would seem to be (unecessarily) limited with respect to the ability to accurately preview low-level image-noise as it would appear when viewed in color-spaces having wider gamuts.

Thus, the linearized low-level region of an sRGB (only) system would not serve to accurately reflect the appearance of image-noise when rendered in and saved to ProPhoto RGB (which has a lower threshold of low-level linearization), or Adobe RGB 1998 (which has no low-level linearization at all).

For such (albeit not necessarily the most common) scenarios, having the ability via user controls to (in the preview display) accurately simulate the low-level gamma-correction functionality of wider gamut color-spaces would seem to be a useful option (existing as an alternative to the default settings).

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