[sane-devel] Canon LiDE 90

[Guillaume Gastebois]

 >But you can ignore led-calibration for now, that is not essential when
 >debugging the backend. Just make sure the exposure settings in
 >Genesys_Sensor.regs_0x10_0x1d are good, for example from an usb log the
 >last register write to 0x10-0x15 before receiving actual scanned data.
 >If those stay all zero, the rgb-leds in your scanner are very probably
 >not controlled using the rgb-led-control-feature of the gl84x.
 >
 >You can disable led calibration by commenting out the code in
 >genesys_flatbed_calibration. Offset/Gain calibration can be commented
 >out when the values in Genesys_Frontend are good, Shading calibration
 >can be disabled when you add OPTICAL_FLAG_DISABLE_SHADING to the flags
 >for gl841_init_optical_regs_scan. When shading calibration is disabled,
 >you get vertical stripes, the others lead to too dark/bright r/g/b 
 >channels.
 >
 >Things that may be missing:
 >* leds need to be controlled correctly
 >* cis-sensor needs to get the correct clock signals(line toggle+pixel
 >  clock, half-resolution signal is optional for now)
 >* the analog frontend registers need to be setup correctly in
 >  Genesys_Frontend
 >* the readout position in the data stream from the analog frontend may
 >  need tweaking(registers 0x52,0x53)
 >
 >When that is done, you should be able to get an image from your
 >scanner, although calibration may be lacking.
 >
 >Regards,
 >  Pierre

OK, i see some image (very far to end result...). But can you explain to 
me how to know the correct values for genesys_frontend ????
These parameter have big influence on resulting image.

Thank you.
Guillaume