Dynapik offers a free online tool to change image types - no need to download anything. It's quick and easy to use. You can change your FAX images to XPM format. This tool works for both professionals and casual users. Convert your images to XPM in seconds.
Group 3 FAX
The raw compressed data stream used by classic fax machines.
When we talk about the 'FAX' file format, we typically refer to a raw data stream compressed using the CCITT Group 3 (G3) or Group 4 (G4) algorithms. These are specialized compression methods designed for bi-level (black and white) images of text documents. In most modern contexts, you won't see a standalone `.fax` or `.g3` file. Instead, this compression data is wrapped inside a container like TIFF or PDF. A `.fax` file is essentially a headerless chunk of this compressed data, which makes it difficult for modern software to open without knowing the specific dimensions (width/height) beforehand.
Group 3 compression is based on Huffman coding and Run-Length Encoding (RLE). It scans a line of pixels and records the lengths of alternating runs of black and white pixels. Because most documents are largely white space, this results in significant compression. Group 4 is an improvement that uses 2D compression (referencing the previous line to predict the next), offering better ratios but requiring an error-free transmission channel (like a digital network), unlike G3 which had to survive noisy phone lines.
Standardized by the CCITT (Consultative Committee for International Telephony and Telegraphy), now ITU-T, in 1980 (Group 3) and 1984 (Group 4). These standards enabled the global fax boom of the 80s and 90s.
X PixMap
Color icons written as text.
XPM (X PixMap) is the usage successor to XBM. It allows for color images (and transparency) to be stored as C source code arrays. It was the standard format for icons in the Common Desktop Environment (CDE) and many Unix window managers.
An XPM file is valid C code defining a character array: `static char * icon[] = { ... }`. The data defines a color palette (mapping characters like '.' or '#' to hex colors) and then draws the image using those characters. This makes it human-readable and editable in a text editor.
Developed by Groupe Bull in 1989 to bring color support to X11 icons.
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