Re: Another Bug (?): "Edge" Printing
Robert Krawitz <rlk <at> alum.mit.edu>
2011-03-05 01:33:34 GMT
On Fri, 04 Mar 2011 17:06:04 -0500, Simon Shapiro wrote:
>
> Setup: Linux 2.6.37, Gimp 2.6.11, Gutenprint 5.2.6,
> Epson R1900 printer
>
> Subject: iT8.7 Reference Target. Sized to 8.5x11", reduced to 4.11x5,
> printed 4up on 8x10 sheet of Luster Premium Photo Paper.
>
> Configuration: See attached .gimp/printc-trimmed file
>
> Problem: Leading Edge image degradation
> Trailing Edge image degradation
>
> Observed: Enabling Quality Enhancement;
> Level 1: Works properly
> Level 2: Leading Edge: Cyan and Light (without
> Densitometer, estimating) +15R, +20D
> Trailing Edge: Last inch gradually faded.
Looking at your printrc, this was at 2880x2880 SW.
I do know about this problem, but unfortunately don't have a fix.
Essentially, quality enhancement uses extra passes to achieve more
uniform printing. Each level doubles the number of passes. In
effect, printing 2880x2880 at QE=1 prints as many passes as 5760x2880;
QE=2 prints as many passes as 5760x5760 would, and so forth.
Unfortunately, many (but not all) Epson printers have problems at the
leading and trailing edge of the paper (not the image -- if the edge
of the image is well away from the leading and trailing edge of the
paper, I believe that it works fine, although I haven't tried it in a
while) when the effective resolution is extremely high. The only
workaround is to refrain from using those very high combinations. You
may find that 5760x1440 or 2880x2880 with QE=0 (turned off) gives you
the best results near the leading and trailing edge of the paper,
although it may not be quite as good away from the edges. My
recollection is that the trailing edge has the most problem (fading
out).
> Elaborated: Leading edge problem does not exhibit fine banding, "grain"
> is uniform but density is substantially diminished and color
> is severely cyan.
> Trailing edge appears like multipath diminishing; on the
> last inch or so, fine bands are increasingly visible, and
> gray image fades to almost white. Also, print fails to
> completely eject from the printer.
>
> Caveat: This only happens to the second and fourth print on the
> page. This means the prints start at 5" from the leading
> edge. It does _not_ happen on the leading edge (prints
> span 0-5" of the 10" dimension.)
>
> Aggravate: Switch Color Correction from "Uncorrected" to High Accuracy"
I don't think this really aggravates it, although depending upon the
exact colors it may make it look worse.
> Work Around: Switch to QE=1 reduces/changes the problem greatly:
> LE seems almost perfect but the very leading edge (first
> few scan lines) shows a square tooth pattern; dark=0.016",
> light=0.008", light~0.5*dark.
> However: Going from QE=1 to QE=2 turns the print, overall
> slightly light and cyan.
>
> Priority: High, unless there is a way to print an 8x10, as a 10x8;
> make the 10" side the leading edge. This is very good as
> it enables printing 8x10s on 10" paper without waste.
> There is no work-around for cut-sheet paper, other than
> over-sizing (expensive!).
There isn't that I know of, unfortunately. We're using the printer in
ways that aren't officially supported, and the firmware probably has
trouble with it.
> If it will help, I will try to provide some close-up photographs. I
> cannot place my camera at the moment.
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