[filmscanners] RE: 8bits vs. 16bits/channel: can the eye seethe difference

["Austin Franklin" <austin@darkroom.com>]

Hi Roy,

> I think you missed the rest of Paul's statement.  As he says "finer
> gradations are indeed represented in an 8-bit image through dithering".
>
> If you scan a real image in 16-bit mode and there are more gradations
> between say 128 and 129, even after converting to 8-bit mode there
> will still be gradations between a pure 128 and a pure 129 patch.
> Photoshop creates these extra gradations by dithering the transition
> between 8-bit values.

Then it really wouldn't matter if they existed or not, as it simply wouldn't
know...and it would create them anyway, right?

> In fact, by default, even the gradient tool
> smoothes transitions from one 8-bit values to the next -- you don't
> get 256 steps you get a smoothed gradient from end-to-end.

What about any other display program (not PS), or printing?  I mean, the 8
bit data is simply 8 bit data, the "in between" data just doesn't exist.
Creating this "in between" data has to be something that is deliberately
done, and it may in fact be creating something that didn't exist in the
first place!

I did not know PS did this, thanks for the info.  Do you have a pointer to
where it is documented?

Regards,

Austin

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