## Brainfuck X

While browsing StackExchange PCG questions and answers, I came across a challenge regarding drawing the swiss flag. In particular, I was interested in benzene’s answer, in which they showcased a Brainfuck dialect capable of creating two-dimensional 24-bit color images. In this post I present this dialect with slight changes of my own, as well as an interpreter I wrote in Python 2.7 (source code is listed below and can also be downloaded).

Urban Müller’s original Brainfuck (my vanilla Brainfuck post can be found here) works similar to a Turing machine, in that the memory consists of a theoretically infinitely large tape with individual cells which can be modified. What allows Brainfuck X (or Braindraw, as benzene called their dialect) to create color images is, that instead of a one-dimensional tape, a three-dimensional tape is used. This tape extends infinitely in two spacial dimensions and has three color planes. Each cell’s value is limited to a byte (an integer value from 0 to 255) which results in a 24-bit color depth.

Adding to Brainfucks eight commands (`+-<>[].,`), there are two characters to move up and down the tape (`^v`) and one character to move forwards in the color dimension (`*`). Starting on the red color plane, continuing with the green and ending in the blue. After the blue color plane, the color planes cycle and the red color plane is selected. benzene’s original language design which I altered slightly had three characters (`rgb`) to directly select a color plane. Whilst this version is supported by my interpreter (the flag `--colorletters` is necessary for that functionality), I find my color star more Brainfucky — directly calling color planes by their name seems nearly readable.
Brainfuck’s vanilla eight characters still work in the same way, Brainfuck X can thereby execute any vanilla Brainfuck program. Also, there still is a plaintext output — the tape’s image is a program’s secondary output.

Having executed the final Brainfuck instruction, the interpreter prints out the tape to the terminal — using ANSI escape codes. Because of this, the color depth is truncated in the terminal view, as there are only 216 colors supported.
For the full 24-bit color depth output, I use the highly inefficient Portable Pixmap Format (.ppm) as an output image file format. To open .ppm files, I recommend using the GNU Image Manipulation Program; specifying the output file name is done via the `--output` flag.

The Swiss flag image above was generated by benzene’s Braindraw code (see their StackExchange answer linked to above); the resulting .ppm file was then scaled and converted using GIMP.
Interpreter command: `python brainfuckx.py swiss.bfx -l -o swiss.ppm`

#### Usage

• Being written in pure Python, the interpreter is completely controlled via the command line. The basic usage is `python brainfuckx.py <source code file>`; by using certain flags the functionality can be altered.
• `--input <input string>``-i <input string>` specifies Brainfuck’s input and is given as a byte stream (string).
• `--simplify`, `-s` outputs the source code’s simplified version; the source code with all unnecessary characters removed.
• `--colorstar` selects the color star color plane change model which is the default.
• `--colorletters`, `-l` selects the color letter color plane change model.
• `--silent` stops the interpreter from outputting warnings, infos and the final tape.
• `--maxcycles <cycles>`, `-m <cycles>` defines the maximum number of cycles the Brainfuck program can run; the default is one million.
• `--watch`, `-w` allows the user to watch the program’s execution.
• `--watchdelay <delay>` defines the time in seconds the interpreter sleeps between each watch frame.
• `--watchskip <N>` tells the interpreter to only show every Nth cycle of the execution.
• `--output <output file name>`, `-o <output file name>` saves the final tape as a .ppm image file.

``# Python 2.7 Code; Jonathan Frech, 24th, 25th of August 2017``

## Asciify

Most images nowadays are represented using pixels. They are square, often relatively small and numerous, come in $(2^8)^3$ different colors and thereby do a good job being the fundamental building block of images. But one can imagine more coarse-grained and differently shaped pixels.
An interesting fact is, that in most monotype fonts two characters placed right next to each other (for example ‘\$\$’) occupy roughly a square area. So simple ASCII characters can indeed be used to approximately describe any ordinary image.
Asciify does exactly this; it takes in an image and some optional parameters and maps the pixels’ intensity onto a character set. Both the large and small default character sets are taken from a post by Paul Bourke.

In conjunction with `asciify.py`, I wrote `index.py`, which asciifies a bunch of images and results in their html form; it also creates an index. All images asciified for this post can be viewed through this index.

Converting an image to its asciified form works best when there is a lot of contrast in the image. Because of this, some pre-processing of the image may be required for best results (all images shown where only cropped or rotated). The built-in color functionality also only knows of $8$ colors, so bright and different colors look the best, as they interestingly differentiate from one another. The asciified image’s size also plays a role, the larger it is, the better the characters blend into one and appear to be one image.

Asciify is operated on a command prompt; `python asciify.py img.png`. To parse arguments, the built-in python module `argparse` is used. The images are opened and read using the Python Imaging Library module `PIL`, which needs to be installed for this program to work.
Optional arguments include `--size N`, where the maximum size can be specified, `--invert` and `--smallcharset`, which can sometimes increase the asciified image’s visual appeal and `--html`, which will output an html file to be viewed in a browser. To see the program’s full potential, simply run `python asciify.py --help`.
Source code for both `asciify.py` and `index.py` can be downloaded, the first is also listed below.

The two examples above use the color mode, though certain images also work in default black and white mode, such as this spider I photographed.

Then again, the colored text also has its charm, especially when the source image has bright colors and a lot of contrast.

``````# Python 2.7 Code
# Jonathan Frech 3rd, 4th of March 2017
#      rewritten 12th of April 2017
#         edited 13th of April, 13th, 14th, 15th of July 2017``````