X PixMap

An X PixMap (often abbreviated as XPM) is a plain text-based image file format primarily used within the X Window System. It defines a color bitmap image in a human-readable way, essentially representing the image data as a series of characters that map to specific colors.

The XPM format's primary advantage lies in its simplicity and portability. Being text-based, it can be easily transferred between systems and edited with standard text editors. This also makes it convenient for embedding small images directly into source code, particularly C code, as arrays of character strings.

XPM files consist of a header section that defines the image's dimensions (width and height), the number of colors used, the number of characters per pixel, and a character-to-color mapping. Following the header is the actual pixel data, represented as a sequence of characters that correspond to the colors defined in the character-to-color mapping.

While its simplicity made it a popular choice for icons and small graphics in the past, the XPM format is less efficient than binary image formats like PNG or JPEG, particularly for complex images or those with many colors. Consequently, XPM is less commonly used in modern applications, which generally favor the superior compression and performance offered by alternative image formats. However, it remains valuable for specific use cases where embedding images directly within code or requiring maximum portability is paramount.