Digital BW, The Print

----- Original Message ----- 
From: "johngeyles" <jge@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Monday, June 09, 2003 1:29 PM
Subject: [Digital BW] Re: Working in 8 bit then converting to 16 bit??


(snip earlier)
>
> I am purely speculating here ... but one can imagine an 8bit->16bit
> conversion that is not quite as straightforward and might create
> a better image.  The idea would be to make the hi-byte of the 16bit
> value equal to the 8bit value, and then put a random value into
> the low-byte.   This has the effect of reducing "mock bands" at the
> transitions between the 256 values; it is frequently used in
> computer image generation systems.  However, I'd be very surprised
> if Photoshop does this when you convert "mode" from 8bit to 16bit,
> in which case this wouldn't explain the supposed improvement from
> OPM when you give it 16bit images,
>

John,

As Roy says I doubt PS does this but it would perhaps make an interesting
tool or plug-in. Especially if you could control the width of the band and
apply it through a mask in PS. Perhaps even applying it after PS converts
from 8 to 16 bit. With 256 tones between each adjacent 8-bit tone converted
to 16-bit you have a lot of room to play with. You could even adjust the
distribution of random tones generated using different curve shapes.

I suspect that if you didn't control the amount and location of added tones
you would start to lose sharpness and resolution. Used well it might be a
great tool for smoothing out broad tonal transitions.

Martin Wesley