Obfuscating images

Question

I want to distribute a few images and not allow others to see them unless they are using my program. My intention will be to use JPG files in which I will alter the header so other image viewers cannot read them anymore. For example I can delete the bytes 7-10 which are the magic signature for JPG. Later, my program will reconstruct the header and show the JPG file.

Question: how do I do this on the fly, without reading the “broken” JPG file, restoring the header, saving the good file to disk and then re-loading it as a “good” JPG file?

Answer 1

Load the "broken" file into a TMemoryStream, patch the bytes in-memory, and use TGraphic.LoadFromStream() to load the fixed JPG file.