8 Bit or 16 bit , sRGB or Pro Photo

Started Sep 11, 2019 | Discussions thread
technoid Senior Member • Posts: 2,276
Re: The difference is ...

Ken60 wrote:

Ok lots of replies and comment , I too have been printing with the Pro Photo and 8 / 16 bit. Yes the differences are small , however I have one or two things I want to eliminate before drawing a final conclusion.

When many speak of a colour space they almost give it colour. It has none , it is only a container into which we place data and allow the space to define the interrelationship between that data and its use. So an empty container ....... As this space grows from sRGB to ProPhoto so with the same data content (8 bit) , the transitions must show differently to a higher, more intricately defined amount of data.

There are areas where the finer granularity of sRGB compared to ProPhoto can result in smaller dE's between a high bit RGB value and an 8 bit RGB value. The difference can be significant if the rounding of the high bit values happens at the most sensitive RGB values. Specifically:

High bit sRGB (31.51 29.49 27.51) and 8 bit (rounded) sRGB (32,29,28) Produces a dE2000 of 1.07.

ProPhoto RGB is more sensitive:

High bit ProPhoto RGB (19.49,16.51,9.49) and 8 bit (rounded) ProPhoto RGB (19,17,9) Produces a dE2000 of 2.44.

So patches of these RGB values in 8 and 16 bits, side by side, will show visible differences. For sRGB, just barely. For ProPhoto RGB, more distinctly visible. You should be able to see the differences with a good, 30 bit (3x10) monitor by creating side by side patches in Photoshop.

Virtually all pixels aren't anywhere near this bad and the noise intrinsic in a photo image, as opposed to a synthetic image, makes these anomalies invisible as they are subsumed in the dithering that naturally occurs by the printer as it spreads tiny differences over larger areas because of the limited number of inks.

But it should be clear that the workflow and especially, any editing, should be done in 16 bits. Printing photos will be fine if done in 8 bits if necessary but one should try to stay in high bit prior to that.

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