pic2ascii | A command line ASCII image interpreter .. | Computer Vision library

Interseting problem its basically vector form of Image to ASCII art conversion... I managed to do this with this algorithm:

1. preprocess image

   You gave us JPG which has lossy compresion meaning your image contain much more than just 2 colors. So there are shades and artifacts which will screw things up. So first we must get rid of those by thresholding and recoloring. So we can have 2D BW image (no grayscales)

2. vectorize

   Your maze is axis aligned so it contains only horizontal and vertical (h,v) lines. So simply scan each line of image find first starting wall pixel then its ending pixel and store somewhere... repeat until whole line is processed and do this for all lines. Again do the same for rows of image. As your image has thick walls ignore lines sorter than thickness threshold and remove adjacent (duplicates) line that are (almost) the same.

3. get list of possible grid coordinates from h,v lines

   simply make a list of all x and y (separately) coordinates from lines start and end points. Then sort them and remove too close coordinates (duplicates).

   Now the min and max values gives you AABB of your maze and GCD of all the coordinate-lowest coordinate will give you grid size.

4. align h,v lines to grid

   simply round all start/end points to nearest grid position ...

5. create text buffer for maze

   AABB along with grid size will give you resolution of your maz in cells so simply create 2D text buffer where each cell has NxN characters. I am using 6x3 cells which looks nice enough (square and with enough space inside).

6. renmder h,v lines into text

   simply loop through all lines and render - or | instead of pixels... I am using also + if the target position does not contain ' '.

7. convert 2D text array into wanted text output

   simply copy the lines into single text ... or if you clever enough you can have 1D and 2D at the same memory place with eol encoded between lines.

Here simple example in C++/VCL I made from the exampe in the link above: