6000000*sizeofpixel. and pixels are 3 bytes in 8 bit/color, or 6 bytes in "more than 8 bit/color" mode. which comes down to either 18MB or 36MB. that is, if it's uncompressed format. for jpegs, it's only 8bit/color, and should be about 2MB (but it *really* depends on how far you are compressing it )
Best, Mishka
