pnm2ppa

pnm2ppa [options] [pnmfile]

pnmfile
    The input PNM image file. If omitted, pnm2ppa reads from standard input.

-o outfile
    Specifies the output file for the PPA data. If omitted, output is sent to standard output.

-c color_mode
    Sets the color mode: 0 for black & white, 1 for color (default: 1).

-d density
    Controls print density: 0 for normal, 1 for high (default: 1).

-q quality
    Sets print quality: 0 for draft, 1 for normal, 2 for best (default: 2).

-g gamma
    Adjusts the gamma correction value (default: 1.5).

-f feed
    Determines whether to send a form feed character at the end of the job (default: 1 for true).

-l left_margin
    Sets the left margin in 600dpi dots (default: 0).

-h high_margin
    Sets the upper-right margin in 600dpi dots (default: 0).

-r right_margin
    Sets the right margin in 600dpi dots (default: 0).

-s scan_mode
    Sets the scan mode: 0 for unidirectional, 1 for bidirectional (default: 0).

-t top_margin
    Sets the top margin in 600dpi dots (default: 0).

-x x_res
    Sets the horizontal resolution in dots per inch (default: 600).

-y y_res
    Sets the vertical resolution in dots per inch (default: 600).

-v
    Enables verbose output, showing progress and additional information.

pnm2ppa is a utility from the Netpbm package that transforms Portable Anymap (PNM) image files into a proprietary HP PPA (PhotoREt Printer Access) format. This specific format was primarily used by older HP DeskJet series inkjet printers, such as the DeskJet 710C, 720C, 810C, 820C, 1000C, and 1100C, which utilized HP's PhotoREt color layering technology for enhanced photo quality.

The command takes a PNM image (which can be PBM, PGM, or PPM) as input, either from a specified file or standard input, and outputs the PPA data to standard output or a designated file. This output can then be directly sent to a compatible HP printer. While modern printers often use standardized protocols like IPP or universal drivers, pnm2ppa remains useful for supporting legacy hardware or for specific embedded systems where precise control over the printer's native format is required.

pnm2ppa is designed for specific older HP DeskJet printers that utilize the HP PhotoREt PPA format. It does not support all HP printer models or modern printer protocols (like PCL, PostScript, or IPP). Its functionality is largely superseded by generic printer drivers (e.g., CUPS) in modern Linux distributions, which handle proprietary formats transparently.

The output is raw printer data and should typically be sent directly to a printer device or spooled via a printing system configured for direct raw printing.

To convert a PPM image to PPA format and send it to an HP printer connected via USB, you might use:
ppmtoppm myimage.ppm | pnm2ppa -q 2 -c 1 > /dev/usb/lp0
Or, to a file for later spooling:
pnm2ppa input.pnm -o output.ppa

pnm2ppa is a component of the Netpbm project, a long-standing and widely used suite of graphics conversion tools for Unix-like systems. Netpbm originated in the late 1980s/early 1990s as a collection of `pbmplus` tools by Jef Poskanzer. Over time, it evolved into the `netpbm` package, maintaining its philosophy of simple, pipe-able tools for image manipulation.

pnm2ppa was developed to address the need for Linux and Unix users to print to specific HP DeskJet printers that required their proprietary PPA format, a common challenge before the widespread adoption of universal printer drivers and standardized printing systems like CUPS. Its inclusion reflects Netpbm's goal to provide comprehensive image conversion capabilities, even for niche or proprietary formats prevalent at the time.

pnm(5), pbm(5), pgm(5), ppm(5), ppatopnm(1), cups(1), lpr(1)