RE: [APML] Picture Window Pro vs. PhotoShop

["Jon Kolb" <jkolb@datawest.net>]

Hi Jerry,

> I don't think I understand how this can be. If you have an 8 
> bit image on 
> the monitor next to a 16 bit image, they are both being output to the 
> monitor at 8 bits, that is all the monitor will work with.

I don't think I understand it either.  Maybe PW is doing something with
the data, but it's always been more or less obvious to me when I use the
"Convert" transformation to swap from 48-bit to 24-bit in preparation
for saving as a .jpg.  If you have PW, maybe you could try this yourself
and see if you notice anyting.  I notice it more on some images than
others, usually more on shots of lower initial quality, which might be a
factor.
 
> Likewise, you may have a 16 bit image originally and may 
> correct it in 16 
> bits in PW, but before you output it to a printer, it has to 
> be converted 
> to 8 bits. Printers only work in 8 bits.

True, and the difference in prints made at each bit-depth is much less
noticeable, but I guess I've always attributed that (without any hard
technical cause to do so) to the way I think ink moves when it hits
paper.  I also have a hard time getting my prints to look like my
monitor image (I haven't yet investigated any of the applications that
are supposed to help out with this), so this effect my be some kind of
perceptual inertia induced by the difference between monitor and print
medium I have stuck in my mine (or some other factor I can't pin down).
Like I said, my observations are not necessarily technical, but
aesthetic and subjective.  It might also explain why I don't sell a lot
of prints (not that I actually try too hard).
 
> Photoshop, btw, only really operates in 15 bits, not 16, they 
> are actually 
> pulling a trick.

And perhaps PW is pulling something on me, too, but I'm sure I see a
difference on the monitor when I swap from 48-bit to 24-bit.  The new
24-bit image always seems just a tad less sharp, with the colors just a
tad more washed out. 
 
> Must be the placebo effect. <G>

Don't rule it out!  There's a lot of momentum behind preconceptions -
maybe I'm just seeing less sharpness and color because I believe that
24-bit should look inferior to 48-bit.  It could be very instructive as
to how the brain perceives color and clarity, if there were a totally
objective means to measure these factors. If you're aware of a
relatively simple (actually, make that "low cost") way to investigate
this, I'd be interested in trying it out.  OTOH, if you're conditioned
to believe that 24-bit and 48-bit images should look the same, then you
might have some inertia to overcome to see any difference, if such a
difference actually exists.

I'd probably make a good test subject, since my education and experience
lie in technical areas having nothing to do with optics, imaging, or the
electronic representation of images - probably one reason I'm drawn to
the hobby in the first place; it's a new challenge, er...make that
"adventure."

Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@datawest.net





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