You can send a report to a tiff file by setting the printer to a fax printer and

REPORT FORM Your.frx NOCONSOLE TO file outfilename.tif

>>As far as I see that code works with existing images, but I need something that I can use as a printer driver or as PS -> image converter.
>
>OK, now the problem is more clear. Maybe Frx2Any? It claims that can convert reports to BMP files.