Question

Hi everyone
I think this is a simple question but its got me stuck. I’ve been using the Leptonica image library and came across the term “Words Per Line” or “WPL”. I tracked down the code but have no idea what its for:

wpl = (width * depth + 31) / 32;

Has anyone ever come across wpl when working with images?

Thanks,
Laurence

Answer 1

Somewhere along the pipeline the software (or hardware) only wants to deal with multiples of 32 bits.

WPL is computed by the formula you quote as the number of 32-bits words necessary to represent a line. width * depth means the number of pixels per line multiplied by the number of bits per pixel. This multiplication results in the number of bits per line.

The ( + 31) / 32 part rounds up to the next integral number of 32-bit words.