pnm2ppa

pnm2ppa [options] [pnmfile]

-copies
    Specifies the number of copies to print.

-brightness
    Adjusts the brightness of the image (0-100).

-gamma
    Applies gamma correction to the image.

-dither
    Enables dithering to simulate more colors.

-nodither
    Disables dithering.

-gray
    Treat the input as grayscale.

-density
    Sets the printer resolution in dots per inch (DPI).

[pnmfile]
    The input PNM file. If not specified, reads from standard input.

The pnm2ppa command converts a portable bitmap (PNM) image format into the HP Printer Performance Architecture (PPA) format, specifically designed for use with certain Hewlett-Packard inkjet printers that support the PPA protocol. The command reads a PNM file (PBM, PGM, or PPM) and outputs the corresponding PPA data to standard output, which can then be redirected to the printer device.
PPA format is a device-dependent raster graphics language used for communication with specific HP printers. This command is particularly useful on systems without dedicated printer drivers or when direct printing is required. The resulting output contains printer-specific commands and raster data to produce the image. pnm2ppa supports various options to control the output, such as setting the number of copies, dithering methods, and printer resolution. This allows users to customize the printing process to achieve optimal results for their specific printer model and image characteristics.

This command is specific to older HP printers that use the PPA protocol. It may not work with newer printers. The output format is printer-dependent, so correct printer selection and option configuration is crucial for proper printing. Dithering algorithms can vary greatly in output quality and speed.

pnm2ppa is mainly compatible with older HP DeskJet and HP LaserJet printers that rely on the PPA (Printer Performance Architecture) printing protocol. Compatibility can be checked by seeing if the target printer supports receiving data directly without a specific driver using PPA.

The command may produce garbled output or fail to print if the specified options (such as density or dithering) are not supported by the target printer. Review the documentation of both pnm2ppa and the printer's specifications.

The pnm2ppa command was developed as part of the Netpbm suite to provide a means of printing PNM images directly to HP printers that use the PPA protocol. It was particularly useful in environments where direct printer drivers were not readily available or needed to be lightweight. Its use has declined with the adoption of more standardized printing protocols such as IPP and the widespread availability of printer drivers. Development focused on supporting a range of HP printers and implementing various dithering algorithms to improve image quality on devices with limited color capabilities. Its functionality has often been superseded by more modern printing methods. Early versions required careful configuration and knowledge of the target printer's capabilities.

pnm(5), ppm(5), pbm(5), pgm(5)