pbmtoppm

pbmtoppm [pbmfile]

[pbmfile]
    The input PBM file. If not specified, pbmtoppm reads from standard input.

The pbmtoppm command converts a portable bitmap (PBM) image into a portable pixmap (PPM) image. PBM is a monochrome image format, while PPM is a color image format. Essentially, this command takes a black and white image and transforms it into a color image where black is represented as black (0,0,0) and white is represented as white (255,255,255). The resulting PPM image is written to standard output, allowing for easy piping to other image processing tools.
pbmtoppm is a part of the netpbm suite, a collection of command-line utilities for manipulating images in various formats. This command is useful for converting simple black and white images to a more versatile color format, making them compatible with a wider range of image viewers and editors. The command doesn't usually have much flexibility and is used just for format conversion.

To convert a PBM file named 'image.pbm' to a PPM file and save it as 'image.ppm', you can use the following command:
pbmtoppm image.pbm > image.ppm
To convert a PBM image piped from another command:
somecommand | pbmtoppm > output.ppm

The pbmtoppm command is part of the netpbm package, a suite of bitmap graphics conversion and manipulation tools that has been around for decades. It was originally developed to handle simple image formats and provide a common set of tools for image processing on Unix-like systems. Its utility has persisted over time due to its simplicity and reliability in performing its specific conversion task.

ppmtojpeg(1), pbmtopng(1), ppmtoppm(1)