Why is scanning to B&W sometimes a larger file than scanning to greyscale?


Example documents are on yellow/manilla paper and all scans are PDF at 300 dpi. The greyscale even has ‘cleaner’ detail and the B&W is more grainy. Typically B&W is 558 kB vs. greyscale at 61 kB.

In: 1

What is the file format?

Can’t confirm without the file format (gif, jpeg, tiff, etc.) but you’re probably looking at a file format that uses compression, and if the black-and-white setting uses [halftones](https://en.wikipedia.org/wiki/Halftone) to emulate the gray scale, the spread of alternating white and black dots is very likely messing up the compression algorithm to result in a very poor compression ratio.