Howdy…
Raw image output from a device is a tricky concept. I’ll provide some examples…
1) real raw data, no phase correction, no dead pixel correction, no interleaving correction, etc; basically a dump of what the CCD or CIS device is reading. I doubt that many scanners provide this.
2) no color or gamma correction. I think this is what most folks mean by the term “raw”, that the dynamic range of the data hasn’t been substantially modified from what the device saw. But the output will still be packed RGB or grayscale or bitonal. Things like ICAP_GAMMA, DAT_GRAYRESPONSE and DAT_RGBRESPONSE should allow you to set up for an uncorrected image. But I suspect that you’ll have a hard time finding a driver that has implemented these options.
3) no meta data. DAT_IMAGEMEMXFER does this. When a driver outputs uncompressed data, it’s up to the application to check DAT_IMAGEINFO or DAT_EXTIMAGEINFO to discover the width, height, resolution and pixel type of the image.
Does one of those sound like what you’re looking for?