[sime2009]

Synthetic images like generated graphs with fine lines and text (i.e. not photographs), need pixel perfect rendering otherwise they look terrible. This is likely to be a far more common and useful use case for images in a terminal than showing photos.

[rbanffy]

For images with fine lines we have both ReGIS and Tek4014. ReGIS specifies pixel values (and became somewhat of a pain when DEC terminals with more than 240 scanlines appeared) but Tektronix graphics work with (IIRC) a coordinate space of 4096x4096 addressable points. It's not too amenable to extensions and has very little functionality besides drawing straight lines in various styles and monospaced text in a couple (3, IIRC) sizes.