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Dear all,
I am programming a small command line tool to do automatic scanning. I developed the program using the twain cmd sample app.
I developed the tool and tested it. But when I use another machine with only USB 1.0, my AVision Scanner only scans a part of the image. How much it scans depends on the resolution. The higher the resolution, the smaller the scan area. It is also noticeable that the sensor speed decreases with increasing resolution.
I tried to set the frame size explicitly, like it is done with the sample app, but this doesn’t help. Also, I tried it with the MFC sample app, it shows the same behaviour.
Since other scanners don’t show this behaviour, i think it is driver or device specific. do you have an idea what i can try?
thanks in advance and bye!
kai
Are you doing a native transfer? If so, the TWAIN spec says a DS can transfer a partial image for a native transfer if it’s in unable to allocate the entire image. See the section “Options for Transferring Data” in chapter 4. I don’t have an AVision scanner so it’s just a guess but changing the resolution does change the memory requirements.
It sounds like that machine has ample memory since other scanners work. For whatever reason, the AVision DS is not able (or willing) to allocate RAM for the transfer. You might have better luck using a memory or file transfer.
If the AVision can transfer an entire high resolution image on a different PC, look at the differences between these two PC’s. For instance, do they have the same version of the AVision driver?
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