Ascgen is an open source software that lets you convert images into text-based art. From wiki “ASCII art is a graphic design technique that uses computers for presentation and consists of pictures pieced together from the 95 printable (from a total of 128) characters defined by the ASCII Standard from 1963 and ASCII compliant character sets with proprietary extended characters (beyond the 128 characters of standard 7-bit ASCII).”
adjust the density levels, brightness, contrast.
add images to it via drag and drop.
convert the whole image, or select just a part of the image.