Graphic photo file to ASCII converter app for Mac?

What I want to be able to do is to get a rough approximation of

the contents of a graphic file, a photo for example but using some

kind of app that can size the file to an 80 column, or standard

width, and then convert is to ASCII characters of relative brightness,

such as a space for all white, and then some other character, perhaps

a # pound sign for black and using other characters for their relative

black and white intensity to map pixel grouping into a 80x(whatever)

matrix for a text display ... ie the Apple Terminal app.

If I had something like this I might be able to compare the graphic

contents of different files to see if they were different sizes but the

same or very close images.

I am looking for an app for my Mac ... not an IOS app, and of course

something that can be run from inside a shell from the command line.

Does anyone know of such a program?

Here is a bad example of what I am talking about ... a hard to see but simple example:

Ooops, I guess I cannot post an ASCII art drawing because the system seems to

think that maybe it is some kind of binary I am trying to upload ???