Some scanners come with a feature called "multi-stream" or “dual-stream". This feature allows you to scan a page once, but retrieve multiple versions of the scanned page (e.g., colored and grayscale). To use this feature, you must set the scanner to the required mode and acquire the scanned page sequentially using the ImageGear C/C++ API.

If there is a single page in the scanner, the scanner is set to “multi-stream” mode and is expected to send a colored and a grayscale image. You can get both images by executing something like this:

#define BUFSIZE 8192
AT_ERRCOUNT Acquire(HISISDRV hDriver)
{
    // Invoke the pipe and scan the page
    return IG_ISIS_run_zone(hDriver, lpBuffer, BUFSIZE);
}