Real-Time ASCII Art Rendering Library
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Real-Time ASCII Art Rendering Library - Live demo:

ASCII Art is a single file C/C++ library that let you transform an input image or video frame into printable ASCII characters at real-time using a single decision tree. Real-time performance is achieved by using pixel intensity comparison inside internal nodes of the tree.

For a general overview on how the algorithm works, check the bottom of the demo page.

Output ASCII art is a related (and older) graphic design technique for producing images from printable characters. This implementation is based on the paper:

N. Markus, M. Fratarcangeli, I. S. Pandzic and J. Ahlberg, "Fast Rendering of Image Mosaics and ASCII Art", Computer Graphics Forum, 2015,


Getting started

Embedding the library in your application is straightforward. All you have to do is drop the ascii_art.c and its header file in your source tree plus the hex model that can be downloaded here and perform the following API calls successively:

  1. Call AsciiArtInit first to initialize the ascii_render structure defined in the ascii_art.h header file.
  2. Prepare the image to be processed by converting it to the grayscale colorspace. You can rely on some external library like OpenCV cvtColor or the built-in AsciiArtLoadImage interface.
  3. Allocate a buffer big enough to hold the entire ASCII text output. The amount of bytes needed is returned via the AsciiArtTextBufSize interface. This step is optional if you do not want a text output but instead a binary ASCII glyphs image.
  4. Finally, transform the input image into ASCII glyphs/text via AsciiArtRender.

Below is a simple C program that demonstrates a typical usage of the ASCII Art C/C++ interfaces.

#include "ascii_art.h"

ascii_render sRender; /* Stack allocated */
/* Initialize the render structure */
/* Load an image from disk */
int width, height;
unsigned char *zBlob = AsciiArtLoadImage(argv[1],&width,&height);
if( zBlob == 0 ){
	puts("Cannot load image");
/* Allocate a buffer big enough to hold the entire text output */
size_t nBytes = AsciiArtTextBufSize(&sRender, width, height);
unsigned char *zText = malloc(nBytes);
/* Finally, process */ 
AsciiArtRender(&sRender, zBlob, &width, &height, zText,1);
/* zBlob[] hold the binary ASCII glyphs now */
/* Output the result */
fwrite(zText, sizeof(char), nBytes, stdout);
/* Release memory */

sample.c source code


  • The C/C++ API reference (Only three interfaces are exported plus another optional), the hex model are all available on the official PixLab page at:
  • The live demo:
  • Please report any issue or feature request here on Github.