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eight bits...eight bits...Posted Jan 11, 2011 15:45 UTC (Tue) by nettings (subscriber, #429)In reply to: Sobotka: Why GIMP is inadequate by gowen Parent article: Sobotka: Why GIMP is inadequate
...might be ok if you don't do very much with your image. the problem is you're going to apply a number of transformations, and then rounding errors accumulate.
take a look at an image histogram after changing the black and white points in colors->curves. that is data loss at work (a particularly graphic case, i admit). why should i put up with gaping holes in my histogram if the original image had 10 or 12 bits of depth?
the discussion is pretty much the same as with cd audio quality. a carefully mastered and dithered cd is capable of totally adequate sound quality. but its underlying format, 16bits at 44k1 sampling rate, is woefully inadequate for studio use. so what everyone does is work at higher bitdepths and possibly higher sampling rate, and only down-convert as a very last step, before the product goes out to the consumer.
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eight bits... Posted Jan 11, 2011 18:24 UTC (Tue) by Imroy (guest, #62286) [Link]
> The problem is you're going to apply a number of transformations, and then rounding errors accumulate.
It's not just rounding errors. If you're dealing with an image using a wide colour gamut, you need the extra precision to properly represent the large colour space. Posterization will result if using 8-bit components with a wide colour gamut.
> A carefully mastered and dithered cd is capable of totally adequate sound quality. but its underlying format, 16bits at 44k1 sampling rate, is woefully inadequate for studio use.
It's important to distinguish between what is adequate for source material and temporary/intermediate results, versus the final output. For the latter, 8-bit sRGB (or CD-Audio) is indeed adequate most of the time. But if you pull that into an editor you may soon have problems from posterization (lack of precision), out-of-gamut colours, blown highlights, lost shadow detail, low resolution, etc.
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