Small C++ program to display images in a (modern) terminal using RGB ANSI codes and unicode block graphic characters.

There are various similar tools (such as timg) using the unicode half block character to display two 24bit pixels per character cell. This program enhances the resolution by mapping 4x8 pixel cells to different unicode characters, using the following algorithm:

For each 4x8 pixel cell of the (potentially downscaled) image:

Find the color channel (R, G or B) that has the biggest range of values for the current cell
Split this range in the middle and create a corresponding bitmap for the cell
Compare the bitmap to the assumed bitmaps for various unicode block graphics characters
Re-calculate the foreground and background colors for the chosen character.

See the difference by disabling this optimization using the -0 option. Or just take a look at the comparison image at the end of this text.