[sane-devel] Epson Perfection 610 Issue with 150 dpi scan

[Alessandro Zummo]

On Sun, 3 Jan 2010 15:14:38 +0100
Rainer Dorsch <rdorsch at web.de> wrote:

> Are these the areas in epson2.c you are refering to:
> 
>         /*
>          * Make sure that the number of lines is correct for color shuffling:
>          * The shuffling alghorithm produces 2xline_distance lines at the
>          * beginning and the same amount at the end of the scan that are not
>          * useable. If s->params.lines gets negative, 0 lines are reported
>          * back to the frontend.
>          */
>         if (s->hw->color_shuffle) {
>                 s->params.lines -= 4 * s->line_distance;
>                 if (s->params.lines < 0)
>                         s->params.lines = 0;
> 
>                 DBG(1, "adjusted params.lines for color_shuffle by %d 
> to %d\n",
>                     4 * s->line_distance, s->params.lines);
>         }
> 
>         DBG(5, "resolution = %d, preview = %d\n",
>             s->val[OPT_RESOLUTION].w, s->val[OPT_PREVIEW].w);
> 
>         DBG(5, "get para %p %p tlx %f tly %f brx %f bry %f [mm]\n",
>             (void *) s, (void *) s->val, SANE_UNFIX(s->val[OPT_TL_X].w),
>             SANE_UNFIX(s->val[OPT_TL_Y].w), SANE_UNFIX(s->val[OPT_BR_X].w),
>             SANE_UNFIX(s->val[OPT_BR_Y].w));
> 
> and
> 
>         /* allocate buffers for color shuffling */
>         if (dev->color_shuffle == SANE_TRUE) {
>                 int i;
>                 /* initialize the line buffers */
>                 for (i = 0; i < s->line_distance * 2 + 1; i++) {
> 
>                         if (s->line_buffer[i] != NULL)
>                                 free(s->line_buffer[i]);
> 
>                         s->line_buffer[i] = malloc(s->params.bytes_per_line);
>                         if (s->line_buffer[i] == NULL) {
>                                 DBG(1, "out of memory (line %d)\n", __LINE__);
>                                 return SANE_STATUS_NO_MEM;
>                         }
>                 }
>         }
> 
> I think a first good step would be to enable debug output.
> 
> How can I enable the output in DBG() from scanimage ?

 Those are two of the involved sections. However I did not wrote
them so I can just hope they work nicely ;)

 You can enable debug with SANE_DEBUG_EPSON2=XX
where XX is a value between 1 and 255.

 Thanks for the remote access offer but I'll be quite busy for the
 forthcoming weeks :(

> >  For such a scanner, I'd suggest to scan a bigger area
> > and then refine by software.
> 
> I to now worry a lot about the 2-3 mm missing in the scan (12 lines at 
> 150dpi), the problem is that the pnm file is broken and most programs reject 
> to work with it. E.g. gscan2pdf uses convert from imagemagick to generate 
> pdfs. But that all only works it the pnm files are correct and not corrupted. 
> For me a fix which at least generates correct pnm files would be fine.

 Did you tried other scanning software?


-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it