[sane-devel] HP5470c scanner nearly working!

[Bertrik Sikken]

Martijn van Oosterhout wrote:

>Yeah, I saw the project but there did not seem to be anything happening.
>However, the hp5400-20021018.tar.gz did form the basis for my program.
>
>Thanks for your report of success. Seems only the version numbers are slightly
>different.
>
>Anyway, I've decoded the images and it now saves them to disk as PPM files.
>If you scan anything with a lot of white you can see that the calibration
>(and gamma correction) definitly needs some work. I have some theories about
>how to get the figures but I havn't done it yet. Interestingly, the full
>preview image includes a section which is within the case itself. Looks like
>some test areas and other odd stuff going on there. I've put the image up
>here: http://svana.org/kleptog/hp5470/output.png (1MB).
>
The white strip with the black square is very similar to what you see in
hp3300, hp3400 and hp4300 scanners.
Also very typical is the shift in color components, where in this case
blue seems to have shifted up exactly 1 pixel and red down 1 pixel.
For the niash backend (which is still not ready by the way...) I solved
this by using a circular buffer that realigns the color components.
This can be a bit tricky, since the shift varies with vertical scan 
resolution.

Regards,
Bertrik

>
>I've not used sourceforge much, so I'm not quite sure what that entails.
>What I would like is information on how to write a SANE backend. I've
>downloaded the source but there does not seem to be any kind of skeleton or
>documentation on how to write a backend. What I've got is easily good enough
>to pass for "beta" in a SANE backend.
>
>Anyway, I've put a new version up on my site
>(http://svana.org/kleptog/hp5470/). Let me know if the images come out OK.
>My xview is having problems showing 48bpp PPM images so you may have to
>convert them to PNG to make them viewable.
>
>Let me know how it goes.
>
>On Thu, Feb 20, 2003 at 09:13:47AM +0100, Thomas Soumarmon wrote:
>
>>Hi Martijn,
>>
>>I began about one month ago to do the same work you've done. Unfortunately 
>>about 2 weeks after the beginning my spare time reduced a lot, so I must say 
>>that it slowed down a lot, reaching a 0 speed for about 1 month.
>>
>>There is now a Sourceforge project set up for hp5400 series SANE backend : 
>>http://sourceforge.net/projects/hp5400backend/
>>and 
>>http://hp5400backend.sourceforge.net/
>>I hope you can get some information there.
>>
>>I think it would be worse you add your work on that project. As you might have 
>>more time than I, would you want to be added as an administrator on that 
>>project ?
>>
>>Another thing. The test program you wrote compiled perfectly and appearently 
>>worked ok. I email you the log directly.
>>
>>Have a nice day.
>>
>