Tak se podívej na přepínače v příkazovém řádku, mělo by to jít (parametr /scan).
/dpi=(x,y) - change DPI values, set DPIs for scanning
/scan - acquire the image from the TWAIN device - show TWAIN dialog
/scanhidden - acquire the image from the TWAIN device - hide TWAIN dialog
/batchscan=(options) - simulate menu: File->Batch Scanning, see examples below
/bpp=BitsPerPixel - change color depth of the input image to BitsPerPixel
/swap_bw - swap black and white color
http://www.etcwiki.org/wiki/IrfanView_Command_Line _Options