In Snow Leopard and later, the Image Kit contains classes for scanning and importing from cameras. There is also a low-level structure, ImageCaptureCore. Both platforms are described in the Image Capture Application Programming Guide in the Apple Documentation Archive.
At Leopard, you'll have to use Image Capture , a less documented, less modern, less reliable API. (This is different from the Image Capture app, which has always been great.) I hope you may need Snow Leopard.
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