ppmtoxpm

Convert a PPM image to a XPM image

$ ppmtoxpm [path/to/input_file.ppm] > [path/to/output_file.xpm]

$ ppmtoxpm [[-n|-name]] [prefix_string] [path/to/input_file.ppm] > [path/to/output_file.xpm]

$ ppmtoxpm [[-h|-hexonly]] [path/to/input_file.ppm] > [path/to/output_file.xpm]

$ ppmtoxpm [[-a|-alphamask]] [path/to/alpha_file.pgm] [path/to/input_file.ppm] > [path/to/output_file.xpm]

ppmtoxpm [-maxcolors N] [-closecolors N] [-gamma N] [-verbose] [-name string] [-comment string] [-alpha] [-mono] [-noalpha] [-optimizetrans] [ppmfile]

-maxcolors N
    Reduces the number of colors in the output XPM image to a maximum of N.

-closecolors N
    Specifies the closeness factor for color reduction, influencing how similar colors are treated.

-gamma N
    Applies gamma correction with a value of N to the image before conversion.

-verbose
    Prints informational and debugging messages during the conversion process.

-name string
    Sets the name of the XPM image data structure in the output file to string.

-comment string
    Adds string as a comment line in the generated XPM file.

-alpha
    Explicitly includes the alpha channel in the XPM output, if present in the PPM. Typically implies XPM3.

-mono
    Forces the output XPM to be monochrome (black and white).

-noalpha
    Explicitly excludes any alpha channel from the XPM output, even if present in the PPM.

-optimizetrans
    Optimizes the transparent pixels, potentially reducing the XPM file size.

ppmtoxpm is a command-line utility from the Netpbm package used to convert image files from the Portable Pixmap (PPM) format to the X Pixmap (XPM) format.

PPM is a simple, raw pixel format, while XPM is a text-based format primarily used for icons, cursors, and small images within the X Window System. XPM supports transparency and can be embedded directly into C code, making it useful for developers.

This conversion often involves reducing the number of colors in the image, as XPM typically uses a limited color palette. ppmtoxpm provides options for controlling color reduction, gamma correction, and handling alpha channels, ensuring the output XPM is suitable for its intended display environment.

XPM format is inherently limited in color depth compared to true-color PPM images. Using -maxcolors can lead to significant color quantization and quality loss.

Alpha channel support depends on the XPM version; ppmtoxpm typically produces XPM3, which supports it. Older XPM viewers might not display transparency correctly.

If no ppmfile is specified, ppmtoxpm reads the PPM image data from standard input (stdin). This allows for piping output from other Netpbm commands directly into ppmtoxpm.

The converted XPM data is written to standard output (stdout). To save it to a file, redirect the output using `> filename.xpm`.

ppmtoxpm is a standard utility within the Netpbm suite of graphics manipulation tools. The Netpbm project originated in the early 1990s as a collection of graphics filters, evolving from the earlier PBMplus package. As the X Window System gained prominence, the need for converting between various image formats, including to and from XPM, became crucial, leading to the development and refinement of tools like ppmtoxpm to support XPM3 (the most common version supporting transparency).

anytopnm(1), pnmtoppm(1), xpmtoppm(1), ppm(5), xpm(5), netpbm(1)