Hi, I still do not quite understand. When I tried to scan the same image using Twain, there was no gray background. What could be the reason?
And I could not find the option to set the option brightness/contrast when I ran: scanimage --help -d fujitsu:/dev/usb/scanner0. Thanks, Peter ----- Original Message ----- From: "m. allan noah" <[email protected]> To: "Peter Chen" <[email protected]> Sent: Tuesday, May 13, 2003 8:43 AM Subject: Re: [sane-devel] Why is the background of the scanned image not a constant grayscale > > ok, a few points: > > 1. never, ever send someone the routing numbers on the lower edge of a > check. > > 2. the gray background that you see cannot be avoided. it is the > reflection of the wight stripe on the opposite read head. open your > scanner, and notice the bottom read head has a white plastic stripe bellow > it. the top read head has a wight plastic stipe above it. these line up > when the unit is closed. > > 3. immediately around the check, there is a darker line. this is a shadow > caused but the thickness of the edge of the check. there is no way to > avoid it. > > 4. if you scan the check in the middle of the adf, you would need to set > the -l to something higher, to cut off the background, then you dont have > to deal with it. you just have to cut it off, or turn up the > brightness/contrast to make the back completely wight. > > allan > > On Mon, 12 May 2003, Peter Chen wrote: > > > Hi, > > > > I scanned one check using the command: > > > > scanimage -d fujitsu:/dev/usb/scanner0 --format=tiff > > -l 0 -t 0 -x 100 -y 200 --mode=Gray --rif=yes > ttt.tiff > > > > then on my Windows machine, I converted it to jpg file. > > > > I did not try SCSI yet. > > > > Thanks, > > > > Peter > > > > ps: pls also see the comments below. > > > > > > ----- Original Message ----- > > From: "m. allan noah" <[email protected]> > > To: "SANE Mailing List" <[email protected]> > > Sent: Friday, May 09, 2003 1:56 PM > > Subject: Re: [sane-devel] Why is the background of the scanned image not a > > constant grayscale > > > > > > > 1. what mode are you scanning in, grayscale, lineart, color? > > grayscale > > > > > > 2. what do you mean by layer? the fujitsu driver returns only one frame to > > > the front end, so there should not be a case where there is multiple pixel > > > data available for one physical pixel. > > Sorry, I was not very clear. Please see the jpg file attached. You can see > > outside the edge of the check, there is another layer which is not totally > > white nor totally black. > > > > > > > > 3. does this happen with other front-ends? > > Yes, I used scanimage, and it was the same thing. Actually, I created a > > bitmap file using the data from sane_read in my application to display it in > > Kylix. > > > > > > > > 4. does this happen with the scsi connection instead of usb? > > Sorry, I did not try it yet. > > > > > > > > 5. could you send me directly a copy of an image where you see this? > > Sure. Please see attched jpg file. If you need the tiff or bmp file, let me > > know. > > > > > > > > allan > > > > > > On Fri, 9 May 2003, Peter Chen wrote: > > > > > > > Hi, > > > > > > > > I set up the tl_x, tl_y, br_x and br_y, scanned one image and found that > > > > there was another layer between the real image and the dark background. > > It > > > > was a rectangle, not of constant grayscale. The scanner is Fujitsu > > fi-4120c. > > > > > > > > Could somebody pls tell me how to get rid of this layer? Since when I > > scan > > > > images using Twain, there is not such a layer. > > > > > > > > The reason that I want to get rid of the layer is I need to do some edge > > > > detection and deskewing. If the background is a constant black (or > > white), > > > > then it would be much easier to implement the algorithm. > > > > > > > > Thanks, > > > > > > > > Peter > > > > _______________________________________________ > > > > Sane-devel mailing list > > > > [email protected] > > > > http://www.mostang.com/mailman/listinfo/sane-devel > > > > > > > > > > -- > > > "so don't tell us it can't be done, putting down what you don't know. > > > money isn't our god, integrity will free our souls" - Max Cavalera > > > > > > _______________________________________________ > > > Sane-devel mailing list > > > [email protected] > > > http://www.mostang.com/mailman/listinfo/sane-devel > > > > > > > -- > "so don't tell us it can't be done, putting down what you don't know. > money isn't our god, integrity will free our souls" - Max Cavalera > >
