[sane-devel] PIXMA: MX360 at 2400 x 1200 dpi

Rolf Bensch rolf at bensch-online.de
Thu Feb 9 13:48:32 UTC 2012

Am 09.02.2012 12:52, schrieb ibu ☉ radempa ䷰:
> Thank you!
> I tried the patch with mode Gray and get these results:
> * for 75 up to 600 dpi everything is fine and k=1
> * for 1200 dpi I get similar results as I sent you for Lineart (see
> gray_1200.pnm); the right half of the image appears as overlay, and
> indeed is interlaced: every other vertical line of pixels is from the
> right half; k=1
> * for 2400 dpi scanimage reduces the resolution to 1200; again k=1

Yes, we limited the scanner to 1200 dpi.

> Attached you find gray scans at 1200 and 2400 dpi, which I resized to
> small jpegs, and their logs.
> I think it would suffice to have 1200 dpi (as this takes a long time
> already) and better to fix the interlacing problem than to put effort
> into 2400 dpi.

If we don't want to fix this, we need to reduce max resolution to 600 dpi.

It's not a big deal to fix this. From experience this is a problem in 
post_process_image_data or in one of the called functions shift_colors 
or reorder_pixels.

The attached patch switches image post processing off and extends max. 
resolution to 2400 dpi. Please have a look to the scanned images. Some 
scanners and / or resolutions need special pixel shifting functions. I 
also added a debug output for k.

We only need to look for gray and color scans. What results do you have 
with color scans?

Maybe you can debug this by yourself. You are also welcome to send your 
scanned images and log files to me.

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