An ASCII art converter is a software application that automatically converts an image into ASCII art, using vector quantization. Typically, this is done by sampling the image down to grayscale with less than 8-bit precision, so that each value corresponds to different ASCII character. Using HTML and CSS, many ASCII conversion programs can quantize to a full RGB colorspace, enabling colorized ASCII images.
Some source ports for the popular first person shooter Doom have an algorithm for rendering ASCII art out of the 3D imagery.