JPEG has a standardized compression scheme. Many images use this scheme, and the same tool decompresses all of them. The tool does not require prior knowledge of what any of the images look like when decompressed.
Unpacking a sazen does not rely on knowledge of a particular compression scheme, it relies on knowledge of the referent. This seems pretty different to me.
Furthermore, the fact that you can’t read JPEGs without the right tool doesn’t seem to me like it has much to do with the compression. Raw, uncompressed bitmap files are also pretty unreadable to humans without the appropriate tools. And you can achieve lossy compression of a picture without changing its format, e.g. by reducing its resolution.
JPEG has a standardized compression scheme. Many images use this scheme, and the same tool decompresses all of them. The tool does not require prior knowledge of what any of the images look like when decompressed.
Unpacking a sazen does not rely on knowledge of a particular compression scheme, it relies on knowledge of the referent. This seems pretty different to me.
Furthermore, the fact that you can’t read JPEGs without the right tool doesn’t seem to me like it has much to do with the compression. Raw, uncompressed bitmap files are also pretty unreadable to humans without the appropriate tools. And you can achieve lossy compression of a picture without changing its format, e.g. by reducing its resolution.
Yep, makes sense to me.