RE: Gradient banding
RE: Gradient banding
- Subject: RE: Gradient banding
- From: Scott Olswold <email@hidden>
- Date: Thu, 6 Dec 2001 21:53:30 -0500
Aside from the natural "gradients" that happen in photography due to the
interplay of light on an object, I thought that it was best to create your
gradient in the colorspace of your output device? Am I right, or just old
fashioned?
I mean, when you have a gradient going from RGB(A) to RGB(B), you're going
to have a bunch of little RGB(n) values, enough to go the distance from A to
B, which could get to 256^3 steps depending on the RGB formulation of each
end point (OK, 256^3 is definitely hyperbole, but this is just an example).
When you transform from RGB > CMYK, this gradient is going to have some
steps that translate nicely into gamut, and some that don't. That's your
banding in this case, yes? No matter how well you tweak your profile (or how
good it is to begin with), out of gamut is out of gamut. The only thing you
can try to do is carry the transformation without destroying as much
chromatic data as you would without profiling/color management.
In most cases, I've figured out what the output device can and can't do
relative to DMax and DMin for each component and worked the gradient that
way. But when I've not been able to control the color space of the gradient,
I've always been privy to some banding, really noticeable or not...and then
I've had to resort to some type of Add Noise technique to break up the
pattern in the source image prior to output.
Oh, on another topic.....
I can get pretty decent color out of MS Office, too. Although I don't know
how you get PowerPoint to read the tags, unless you're talking about setting
up ICM in the print driver and monitor property pages (or the ColorSync
option in the print driver Mac-wise). That's what I do, and I don't get paid
very big bucks (mine are medium sized) <g>. The only problem with importing
EPS is that onscreen display is awful, and (particularly with PPT), you are
usually working with a cross-media file. Word, not so much, but definitely
PowerPoint.
Scott Olswold
Senior Systems Support Engineer
MCSE, CNA 5, A+, Adobe Expert User (Photoshop and PageMaker)
Danka Office Imaging