Initial import of sane-backends version 1.0.24-1.2

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+gt68xx.TODO -*-text-*-
+
+General:
+--------
+
+- some sort of fixed lookup-table may be necessary to compensate for the
+  non-linear CCD/CIS behaviour. A gamma value is not good enough. Or maybe line
+  calibration can be used for that?
+- Some Plustek scanners are advertised with e.g. 1200x2400 but the maximum
+  vertical resolution seems to be limited to the horizontal one. Check if
+  that's really the case.
+- Keep a log of all gain/offset combinations already tested and break if
+  one is repeated to avoid endless loops.
+- Print commands that are send to the scanner in clear text.
+- Try to implement non-blocking USB bulk reads, check libusb CVS.
+
+CCD:
+----
+
+Mustek BearPaw 2400 TA Plus:
+- some lines at the beginning of each image have wrong colors (linedistance?)
+  This seems to happen with other scanners, too.
+- 600 dpi no backtrack, 1200, 2400 dpi backtrack (gray), check with windows for
+  color
+- 600 dpi 12 bit seems to work in pixel mode only (but long lines are too big!)
+
+Mustek BearPaw 1200 TA:
+- similar color problem as 2400 TA Plus, doesn't always happen?
+
+Mustek BearPaw 2448 TA Plus:
+- all modes are slow (massive backtracking). If connected to a USB2 port, the
+  backtracking ich much less despite this scanner can't do USB2. Strange.
+- Sometimes there is a USB protocol error when cancelling the scan?
+- top borders move with resolution (happened in the early days with 2400 TA!)
+- gray scans have different brightness
+- scan motor is bumpy and freezes sometimes, looks like accelaration is too big
+  (firmware problem?)
+- vertical stripes
+- TA settings are wrong
+- no backtrack >= 600 dpi (also gray!)
+- don't move before and after scan
+- check jpeg output, maybe this can be used for faster scans
+
+Plustek 1248U:
+- Linedistance seems to have problems in the first few and the last lines.
+- Gain and offset values are quite high. Optimum values are not reached. Problem
+  with coarse calib? Better algorithm needed.
+- Images in color mode sometimes look too redish (result of above problem).
+- quite slow when full width is selected. Lots of backtracking.
+- Check if pixel mode is possible.
+- Check again 600x1200 dpi.
+
+Plustek U16B:
+- 600 dpi 16 bit is limited to about half the size of the scan area because
+  only pixel mode works and 16k is the maximum buffer size.
+- After scanning, a run of sane-find-scanner leads to a protocol error and
+  scanning does no longer work.
+
+Genius ColorPage Vivid 1200XE
+- 16 bit per color is advertized but this mode doesn't seem to work
+  (only 12 bit)?
+- 1200x1200 and 1200x2400 dpi doesn't seem to work despite being advertized
+- Y-positioning varies slightly with resolution (some mm)
+
+CIS:
+----
+
+- It may be necessary to do an additional exposure calibration before the
+  offset/gain calibration to compensate for different intensities of the
+  colored leds. Especially for the Mustek 2400 CU Plus.
+- Changing exposure doesn't seem to have any effect during calibration
+  sometimes while it has an effect on the final image?
+
+Mustek BearPaw 1200 CU
+- ok
+
+Mustek BearPaw 1200 CU Plus (0x021b)
+- ok, but similar exposure problems as 2400 CU Plus
+
+Mustek BearPaw 2400 CU Plus
+- ok, but exposure setting may need to be done automatically if the intensity
+  of the colors varies for different scanners.
+- calibration/exposure has sometimes sharp jumps in intensity. Reason is
+  unknown.
+
+Mustek ScanExpress A3 USB
+- still slight vert. stripes
+- why is line distance setup necessary?
+- line distance varies with resolution (0,5,5 at 300 dpi, 0, 6, 7 with 150 dpi)
+- exposure doesn't seem to have any effect
+
+Mustek ScanExpress 1248 UB
+ok
+
+Plustek OpticSlim 2400
+- only upto 1200 dpi vertical works
+- only 8 and 12 bit work, 16 doesn't (check Windows)
+- exposure is extremely high and seems to have similar problems as with other
+  CIS scanners (reaches limit also)
+
+Mustek ScanExpress 2400 USB
+- make it work (nobody seems to have this device)
+
+Visioneer OneTouch 7300
+- 16 bit doesn't seem to work despite beeing advertized