[sane-devel] LiDE 90 half ccd

[Pierre Willenbrock]

Guillaume Gastebois schrieb:
> Hello,
> 
> I remember that LiDE 90 is a 2400DPI scanner. And I did nothing in code to port
> that. I backend ready for 2400dpi (I think so regarding portion of code) ?

I am not sure, as there could not happen any testing. But in theory, it 
should work. In the future, there should be some afford made to make 
other resolutions than 2400, 1200 and 600 work, but these 3 are trivial 
with this chip.

> I write 2400 dpi in genesys_sensor for lide 90. But how to know pixel number for
> CCD sensor ?

I guess the manufacturer is not lying about the density of the ccd, so 
that should be enough. The rest of the settings is in real units. The 
backend calculates the exact number of pixel from the density and the 
width of the scanning area.

> After writing 2400 dpi in sensor, I get quarter sized images !!! Why ?
> 
> With 600 dpi in sensor I get full sized images with (300dpi scanning) or without
> half_ccd (1200dpi scanning) (with my code for gpio 14).
> 
> Regards
> Guillaume

I'd first try to get the correct gpio setting for a full resolution 
scan(i.E. at 2400dpi). If you cannot get a full-width-scan, look for the 
DPISET register, and try half/twice the dpi there. Also, make sure the 
DPIHW is set for the 2400dpi mode.
When that works, figure out how to setup gpios for half_ccd mode. From 
the view of the current code base, you are done here. You can try to 
find a quarter_ccd mode(which would show up as half-width in the 
half_ccd modes), and leave a comment in the code, or even implement the 
quarter_ccd mode for real.

Regards,
   Pierre