I can imagine that it would be relatively straight forward to write some simple code that converts an image file into a spreadsheet. A bit of header code to specify cell dimensions, then read each pixel in, convert it to an excel cell colour, and write into the spreadsheet file the cell reference and attributes. Then repeat for the next pixel until complete.

Possibly need to scale the image to something manageable so it don’t end up creating a spreadsheet with a million rows and columns.