I have created different uncompressed bitmap images with the same pixel size (2000x2000) and different content (black, red, white and a photograph) expecting the file size in bytes to be exactly the same regardless of the content.
These were the results:
- wc -c command reporting the same size for each image (12000056 bytes).
- Hex Editor reporting identical results in size. I also can clearly see the bitmap pixel information for each RGB channel as expected.
- Mac OSX "Finder" and "Get Info" reporting small differences. (12 106 957, 12 005 274, 12 005 261...)
What could justify these differences? Is this the OS adding some metadata? Something related to the filesystem? Is there any way to know exactly what's going on?
ls -l@
on the files to see their extended attributes and their sizes.