Convert PBM to SIXEL

The PBM (Portable Bitmap) file extension, part of the Netpbm project, originated in the late 1980s to facilitate efficient and portable graphics file interchange. Primarily, PBM files are used to store monochrome bitmaps in a simple ASCII text format, ensuring easy compatibility across different systems and platforms. This format supports only black-and-white imagery, making it particularly useful in scenarios where simplicity and minimalism are prioritized, such as in Unix environments for bitmap manipulation and transfer. Its historical significance lies in promoting a standardized approach to bitmap graphics in early computer technology.

The SIXEL, or "six pixels", is a bitmap graphics format created by Digital Equipment Corporation (DEC) for their terminals and printers. Initially designed for DEC dot matrix printers like the LA50, it enabled the efficient transfer of bitmap graphics using a series of ASCII characters. Each character represents a 6-pixel high row, making it suitable for 7-bit serial communication. This format was later adapted for modern terminal emulators, extending its utility beyond its original scope.