Is it the profile, paper or lack of steps in 8-bit color?
Is it the profile, paper or lack of steps in 8-bit color?
- Subject: Is it the profile, paper or lack of steps in 8-bit color?
- From: Tim Vitale <email@hidden>
- Date: Fri, 01 Oct 2004 16:01:56 -0700
I believe this is a profile issue, but I would like some confirmation...
I'm printing Epson Premium Gloss roll paper on a 9600 using the Bill
Atkinson PGL2 profile pulled from the Epson Pro website. In every other
instance I have found the Atkinson profiles to be superior to anything I
could make using ProfileMaker 4.2.5, for obvious reasons.
However, I'm printing scanned transparencies that look great on the
screen but print with distinct "steps" in the darks where light wraps
around a body. The 40 year old Ektachrome have lost cyan and yellow,
showing a magenta cast which has been corrected. The native tonal range
of the 1966 trannys is about 7 stops (2.1D), they were expanded about
10-20% using Levels. The image on the screen looks smooth, very smooth,
but now that I see the "stepped darks" in the Epson Prem Gloss printed
version, I can see the possible source of the problem. I've printed
about 40 images and half show the problem, which is worse under strong
illumination. The problem appears in the region of 45 RGB (1.7D) to 90
RGB (1.0D), that was 37 (1.8D) to 78 (1.15D) RGB values, before the
"Levels" correction.
This would seem to be a fault of the profile, converting a seemingly
smooth gradient into a "stepped" shading. However, I know the care
Atkinson put into making his 7600/9600 profiles, so I question my
primary diagnosis of the problem.
Another option is that "steps" were introduced in the 10-20% levels
expansion processed. There are 4 RGB values from 1.7-1.8D, and 9 RGB
values between 1.0-1.1D. However, they don't show on either an Apple
Studio 21" CRT or a very good Sony 21" CRT, but do show in the print.
Another alternative is the paper, which I know has "matte surface
regions" or "bronzing" issues in some of the darks passages. The areas
under discussion have matte surfaces that are glossy just before the
"stepped" problem occurs. This suggests the paper may have some part in
the problem. The same image on Ep Prem Luster showed less distinct
"step" artifacts, while the same image on Ep Enh Matte shows absolutely
no step artifacts; all made using Atkinson profiles.
Does anyone have a similar experience, or can they diagnose the fault
from the description of the problem?
Tim Vitale
Print, Drawing and Photograph Conservator
Emeryville, CA
510-594-8277
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