When working on several Photoshop PSD documents that have the same document dimensions (size and resolution) in the same RGB colour space, why do they end up with different file sizes when flattened to a TIFF format with no compression, using the same saving features?
Answer
Different areas within a document need different bytes. File dimensions are only one aspect of a file’s size.
A pixel that is 0/0/255 needs a different set of data than a pixel which is 199/238/175.
Unless every pixel in your documents match, they will always be different in terms of file size.
3 tiffs….
all 500x500px flood filled with a color and saved with the exact same steps. The only variation is the actual pixel data. In fact, the only variation is the color of the document. No embedded color profiles, layers, or transparency.
The sizes will vary based on the pixel data…..
Right-click/Control-click and open image in a new tab/window to see it easier
This slight variation, could be due to the embedded preview image for the file. If the preview is using compression, then the different color fields could be compressing differently. For solid, irrefutable, answers as to why this happens, I think you need to ask Adobe as it’s a tech support issue, not a design issue.
Attribution
Source : Link , Question Author : phil , Answer Author : Scott