ybmtopbm

Convert a YBM image file to PBM

$ ybmtopbm [path/to/input_file.ybm] > [path/to/output_file.pbm]

ybmtopbm [ -force ] [ -verbose ] [ ybmfile ]

-force
    Bypasses certain error checks, attempting to force the conversion even if the input YBM file appears corrupted or non-standard. Use with caution.

-verbose
    Displays detailed information about the header of the input YBM file to standard error. Useful for debugging or understanding the YBM file structure.

`ybmtopbm` is a specialized command-line utility from the comprehensive Netpbm image manipulation toolkit. Its primary function is to convert image files stored in the Yamaha Oki bitmap (YBM) format, an older and somewhat obscure proprietary bitmap standard, into the widely recognized and simpler Portable Bitmap (PBM) format.

The PBM format represents monochrome (black and white) images, where each pixel is either black or white. `ybmtopbm` reads the YBM image data from standard input by default, or from a specified file if provided, and then writes the converted PBM image to standard output.

This filter-like behavior makes `ybmtopbm` highly suitable for integration into Unix-style shell pipelines. Users can chain `ybmtopbm` with other Netpbm tools, such as `pbmtopgm` (to grayscale), `pbmtoppm` (to color), or `pnmtops` (to PostScript), to achieve further format conversions or processing. The utility handles the intricate details of parsing the YBM header and pixel data, translating it into the straightforward PBM structure, thereby enabling interoperability with modern image processing workflows.

The YBM format is relatively obscure, so input files might be rare.
`ybmtopbm` strictly produces monochrome PBM output; any color or grayscale information present in the original YBM (if applicable) will be lost during conversion.
While the -force option can help with problematic files, it does not guarantee successful conversion of severely corrupted or unknown YBM variants.

Like most Netpbm utilities, `ybmtopbm` functions as a filter. It reads YBM image data from standard input (stdin) unless a filename is explicitly provided as an argument. The resulting PBM image data is then written to standard output (stdout). This design facilitates seamless integration into command-line pipelines for complex image processing workflows.

It's important to note that `ybmtopbm` exclusively converts to the Portable Bitmap (PBM) format, which is monochrome (black and white). If the source YBM file contained color or grayscale information, this data will be discarded during the conversion process, resulting in a binary (black or white only) image. Further Netpbm tools are needed for conversion to other color or grayscale formats.

`ybmtopbm` is an integral part of the Netpbm project, a comprehensive toolkit for manipulating graphic files. Netpbm itself evolved from the `pbmplus` package, which was originally developed by Jef Poskanzer in the late 1980s.

Specifically, `ybmtopbm` was written by Bryan W. Headley in 1993. Its development was informed by Bryan W. Headley's prior work on `ybm2eps` and insights from Paul Hethmon's `okigen` source code, demonstrating its roots in earlier efforts to handle Yamaha-specific image data. It has since been maintained as part of the official Netpbm distribution.

pbm(5), anytopnm(1), pbmtopgm(1), pbmtoppm(1), netpbm(1)