Pro RGB...really?

Started Nov 8, 2012 | Discussions thread
technoid Senior Member • Posts: 2,015
Re: My Opinion -- Re: Can someone explain ?....

Vernon D Rainwater wrote:

rpenmanparker wrote:

Vernon, you also have to remember that the change from one color space to another depends upon what rendering intent you choose. In some intents the colors that are not in the target space are just clipped, lost without any replacement. In other intents the color in the source is translated into the closest match in the target space. Or put another way the color in the source are all distriuted over the colors in the target space even if this rests in imperfect matches.


I believe the important thing to be considered is that the conversion (from aRGB to sRGB) obviously results in significant changes in the RGB values -- (regardless of the chosen Intent)

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Colorimetric intents produce very different results for printer profiles because the white point for prints is not Lab(100,0,0). It produces the same results when converting between RGB colorspaces with one major exception. Microsoft interprets white points and reference white differently from Adobe and their color conversion engines, selectable in Photoshop, produce a color shift when the two RGB spaces have different white points when converting to Absolute Colorimetry. For example ProPhotoRGB and sRGB have different white points, D50 and D65, and exhibit color shifts using Microsofts ICM engine in absolute mode. OTOH, AdobeRGB and sRGB have the same white point, D65, and both engines produces similar results.

The usual way color conversion engines handle RGB conversions that are out of gamut is to simply clip the R, G, and or B, to zero. Out of gamut RGB conversions occur when the math matrix calcs produce a negative value in one or more colors. Convention is to simply clip any negative values to zero.

They handle printer profile conversion differently and more as rpenmanparker describes.

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