Image Size in kBytes

To compute an estimation of the size of an image, without taking into account the compression

File Size = (Horizontal pixels * Vertical pixels * Bit Depth) / (8 * 1024 bits)

E.g. : 640 x 400 Black and White Image

File Size = (640 * 400 * 1) / (8 * 1024) = 31.25 kB