Hello, Why calibration is so long (~50/60s) ?
What are /* Start of white strip in mm (y) */ and /* Start of black mark in mm (x) */ in genesys_devices.c ? Regarding the log file you said : W ! 0x23 ! 0x050 ! dac value rgb(offset value) W ! 0x2b ! 0x028 ! pga gain rgb But on debug, I see that these two registers are never written. Another thing : when scaning in color the leds are blue ???? Pierre Willenbrock a ?crit : > Guillaume Gastebois schrieb: >> Hello, >> >> I need a little bit more informations befor testing (sorry for my poor >> knowledge >> in scanner) >> >> Selon Pierre Willenbrock <pierre at pirsoft.dnsalias.org>: >> >>> I don't know why the image colors are reversed, but it may be worth >>> trying to flip the sign bits in Genesys_Frontend. If that does nothing, >>> we need to handle that in code(or i am missing some setting of the gl841). >>> The other thing you have seen is the half-resolution mode, used for >>> greater speed when doing lower(i.E. not full) resolutions. >>> >> How do you explain yhat with half resolution the image seems to be grayscale >> and >> without it seems to be lineart ? > > If you look closely, you see that the image is not exactly lineart. When > doing half resolution, the sensitivity of the scanner sensor changes, > and thus needs a different afe setup. That should be handled gracefully > by the offset/gain calibration, once those are working. > >>>> Subsidary question : what is the small white (perhaps black) rectangle >>>> in the middle up off page (for calibration) ? >>> That may be a small metal clamp holding the glass or the calibration >>> strip. That is the black(i.E. white) part at the very top. >>> >> Under this small rectangle I have a vertical more clear line(same height). >> Is it >> because I need to tweek calibration area (without this small rectangle) ? >> >>> To summarize, it is a good idea to have bit 4 on, bit 5 is the half >>> resolution switch. I'd put 0x10 into the 0x6c gpio register. >>> >>> As for the calibration area, you will need to change some code: >>> * comment out genesys_gl841.c:4220:(line numbers may differ) >>> status = gl841_feed(dev, 280);/*feed to white strip. canon lide 35 only.*/ >>> * the same for genesys_gl841.c:4821: >>> status = gl841_feed(dev, 280);/*feed to white strip. canon lide 35 only.*/ When I comment out these lines the result is very bad (sample http://ggastebois.free.fr/lide90_snoop/toto_10_0_0_comment.jpg) >>> >>> then you can try what happens when you turn on the led_calibration and >>> the coarse_gain_calibration. offset_calibration needs a bit more >>> changes. i think i am having the code needed lying around somewhere. >>> essentially, the offset calibration needs to be done with leds off. >>> the shading calibration does need even more changes. >>> >> Where to find led_calibration, coarse_gain_calibration ? How to turn them on >> ? >> For personnal information : what is shading calibration ???? > > They are called by genesys_flatbed_calibration, i think i requested to > comment them out earlier. OK, sorry, I did that some days ago. My last mail and sample images were WITH led_calibration and coarse_gain_calibration. > > There are three things to calibrate for: > 1) the mapping from sensor voltages to numbers, to not lose color space > by clipping lower brightness to 0 or higher brightness to 65535. > ideally, you don't ever see 0 or 65535 from the afe. This is mainly the > job of offset/gain calibration, but the led-exposure is a factor to this. > 2) the color intensities relative to each other. We try to get each > colored LED to lead to similar voltages in the sensor during its > exposure. This is calibrated by led_calibration > 3) Variations between the sensor cells. each sensor cell has it's own > sensitivity and black voltage, so there needs to be a > per-pixel-correction. This is done by shading_calibration. > > Additionally, the shading_calibration is by-color, so this is the place > where we map each color channel to the correct range, as the > led_calibration is not that exact. > >>> Additionally, if you can't get the afe to switch the sign, you need to >>> do that in the calibration functions(i.E. 65535-value). >>> >> Only in calibration function ? > > For now, that should be enough. We are not interested in the actual > output image, yet. > > Regards, > Pierre > >> Regards >> Guillaume >> >>> Regards, >>> Pierre >>> > > > Regards Guillaume