Digital BW, The Print

> From: glemasurier
> 
> Am I destroying image quality by my workflow?
> 
> 1)  I shoot JPEG and convert to 16-bit using the "mode" in CS 
> to do editing. I convert back 
> to 8-bit to save and before printing. Am I actually achieving 
> anything? Am I affecting my image negatively?

Not a whole heck of a lot. If you tweak your images by doing lots and lots
of curves on top of curves, as opposed to using adjustment layers, then you
might, under some extreme circumstances, see a slight degradation. Where
you're really losing is in shooting JPEG in the first place, assuming your
camera has a raw mode, since JPEG discards maybe a stop or so of dynamic
range from the high end. Also, it discards dynamic range at the low end, but
that's only an issue for quiet cameras at low ISO settings, where eight bits
aren't enough to represent the tiny amount of noise.

> 2) If I change the image size up and down, does that alter 
> the digital file or affect image 
> quality? I usually save the image in its original file 
> size/resolution, but sometimes change 
> image size several times on the file I'm using to print.

Upsizing it can theoretically lose a tiny bit of the highest spatial
frequencies, but typical cameras don't really have enough of those high
frequencies to matter, thanks to the anti-alias filter over the sensor, not
to mention imperfections in the focus. Obviously, you lose detail when you
downsize, though.

I always do all my editing at the native resolution that comes out of the
camera, do a _tiny_ bit of sharpening (just enough that I can barely see it
at 1:1 on the screen), save that as my master finished image, and then
resize down for the web with additional sharpening. For printing, there's
some argument for explicitly resizing to the native resolution of the
printer driver (i.e., 720ppi for Epson desktops, 360ppi for Epson large
format), rather than letting the driver do it, since who the heck knows how
good an algorithm the driver has. But I've never bothered with that, always
getting good enough results letting the printer driver do whatever resizing
it needs to do.

-- 

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...