The driver should disable the gamma table option when it is switched to TPU mode, if this capability is not available. Support for the 8800F is quite new, so I am not surprised to see these sorts of issues. Perhaps Gernot will chime in?
allan On Sat, May 22, 2010 at 2:06 PM, Valentin David <valentin.david at gmail.com> wrote: > I actually discovered that XSane can do the gamma correction in > software. However you have to manually uncheck a box. It should > automatically detect it cannot send a gamma table, but fails. Is it > the mistake of XSane or of the driver? > > On Sat, May 22, 2010 at 6:35 PM, Valentin David > <valentin.david at gmail.com> wrote: >> I had troubles making the gamma correction to work in transparency >> unit mode on my Canon 8800F. Since the problem appeared both on >> xscanimage and XSane, I thought it was probably the driver. So I >> looked the driver source, and understood that in TPU, the scanner does >> not get any gamma table but rather sends 48 bits data. >> >> I also discovered that it was using a gamma table in flatbed mode. I >> tried, and then it does work. Which confirms the thing. >> >> This is great to get raw data. However it seems that the gui frontends >> do not tell you cannot set a table. And also, I cannot use GIMP >> directly. On underexposed or overexposed films, I get quantization >> artifacts. I need to reinstall CinePaint. :( >> >> In XSane, the color correction also gets strange. I do not know if it >> is related. The red looks overexposed, green OK, and blue under >> exposed. >> >> Certainly the driver needs to say if the gamma correction will be done >> or not. And the frontend should apply it on its own if there is no >> correction done. At least for the user not to get this unexpected >> behavior. >> >> -- >> Valentin David >> valentin.david at gmail.com >> > > > > -- > Valentin David > valentin.david at gmail.com > > -- > sane-devel mailing list: sane-devel at lists.alioth.debian.org > http://lists.alioth.debian.org/mailman/listinfo/sane-devel > Unsubscribe: Send mail with subject "unsubscribe your_password" > ? ? ? ? ? ? to sane-devel-request at lists.alioth.debian.org > -- "The truth is an offense, but not a sin"
