Re: [Gimp-print-devel] RE: Epson 1520 issues

[David R. <d_...@nc...>]

Robert L Krawitz wrote:
> 
> 
> Let me know how it works now.
> 

I have finally tried the 1.119 version and the results were 
different but still not correct.  The magenta was horizontally 
offset from the cyan and yellow (by about 2cm to the right) 
and the density seems too low; however, the image was not
expanded in the vertical dimension.  The speed is still
many, many, times slower than 720dpi, apparently still
printing one or two nozzles at a time, with the paper
advancing microscopically between scans.

In order to help make the process less open-loop, I have
taken Eric's suggestion and generated two files from
the output of the Windows driver - one at 720dpi microweave,
and the other at 1440 dpi microweave.  To keep the file size
down, the images are small, but they are big enough so that 
they are at least three or four times the height of the print 
head (which is fairly big on the 1520).  The files should be 
accessable here:

http://www.nccn.net/~w_rosky/dsr/e720.prn.gz
http://www.nccn.net/~w_rosky/dsr/e1440.prn.gz

A few more observations and comparisons regarding the Windows
driver:  

1) I timed the printing of an image in the 1440 and 720 
"microweave" modes.  The 1440dpi image took about four times 
longer to print (head in motion continuously), which seems to 
verify the assumption of two-pass printing.  At 1440, the paper 
advances a small but visible amount between each scan of the 
head, and the head definitely moves more slowly than in 720dpi 
mode (somewhere around 1/2 speed), parhaps to allow increased
settling time.

2) A manually fed piece of paper actually backs up a bit
before the printing starts.  Perhaps this is how they 
attack the problem of vertical offset on the page.  I'm
not sure if the driver or the application is doing this.

3) At 720dpi, the diffusion in the Windows output seems
a bit more smooth with a little less graininess and
patterning even in areas of medium density; however,
the gimp-print driver seems to have better tonality
and contrast (both drivers were used with default
settings).

Regards,

David