RLE to PGM Converter

RLE (Run-Length Encoded) in the context of the Utah RLE format refers to a raster image file format developed by Spencer W. Thomas at the University of Utah's Computer Science Department around 1983, as part of the Utah Raster Toolkit. The format stores images using a scanline-oriented run-length encoding scheme that compresses sequences of identical pixel values into count-value pairs, achieving good compression ratios for images with large areas of solid color — typical of computer-generated graphics and rendered scenes common in computer science research at the time. Utah RLE supports 1 to 255 color channels per pixel, with 8 bits per channel, and includes a header specifying image dimensions, number of channels, background color, and an optional color map. The format accommodates alpha channel data as an additional channel, and empty scanlines (matching the background color) can be omitted entirely for further compression. The Utah Raster Toolkit provided a suite of Unix command-line tools for manipulating RLE images — operations like compositing, scaling, rotating, color manipulation, and format conversion — establishing a software paradigm later echoed by Netpbm and ImageMagick. One advantage is the format's foundational role in computer graphics: the Utah Raster Toolkit and its RLE format emerged from the same research environment that produced the Phong shading model, Gouraud shading, and the teapot — and much of the early computer graphics research output was stored in this format. The format is supported by ImageMagick, GIMP, and various legacy graphics tools.