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Cold, hard reality sets in...

Started Jul 9, 2001 | Discussions thread
Gary Oberbrunner New Member • Posts: 17
Re: Cold, hard reality sets in...

Andrew Grant wrote:

Actually its a very smart question. The correct approach is to
assign the appropriate colorspace when opening the file, convert to
working space for editing then either convert to the printer's
colorspace before printing or have PS do it at print time.

Although your approach does give accurate color at all stages, don't forget that each color conversion loses a little color information, especially if all the stages are 8 bit per pixel (at 10 or more bpp this doesn't matter). To elaborate: the input from the camera goes from 0 to 255 in each channel. If you stretch that channel a little, there will be a few missing codes in the result: e.g. 12 goes to 12 but 13 goes to 14. There's no way to get a 13 in the output. The reverse is true if you're compressing: several input codes will map to the same output. Now if you do a different conversion to the printer's space, you'll get missing/dup codes in a different place, and the end result is each of those missing codes will cause a little bit of banding in the output if you're looking at a smooth gradient. You won't notice this kind of thing on noisy or textured input images.

Not saying Andrew's method is wrong, just reminding folks to watch out for accuracy at all stages. Work at 12 or 16bpp if you possibly can.

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Gary Oberbrunner

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