srftopam

Convert an SRF file to Netpbm format

$ srftopam [path/to/file.srf] > [path/to/output.pam]

srftopam [-alphaout=alphafile] [-fixblack] [-ignore_gamma] [-invert] [-truecolor] [-transparent={color | colorname}] [-verbose] [file]

-alphaout=alphafile
    Extracts the alpha channel from the input SRF and writes it as a PGM (for grayscale alpha) or PBM (for bilevel alpha) file to the specified alphafile. If the input SRF has no alpha channel, this option is ignored.

-fixblack
    Corrects for a common convention in some Sun Rasterfiles where black pixels might be erroneously represented as white. This option ensures that such pixels are correctly mapped to black in the output PAM image.

-ignore_gamma
    Disregards any gamma correction information found in the SRF header. This can be useful if the gamma value in the header is incorrect, outdated, or if you prefer to apply gamma correction separately.

-invert
    Inverts the grayscale or color values of the image. White becomes black, black becomes white, and other colors are inverted accordingly across their respective color ranges.

-truecolor
    Forces the output PAM to be a truecolor (typically 24-bit RGB or 48-bit RGB) image, even if the input SRF is colormapped and could be represented using a smaller color palette. This is useful for preserving full color fidelity.

-transparent={color | colorname}
    Specifies a particular color in the input SRF that should be rendered as transparent in the output PAM. The color can be provided as a hexadecimal RGB value (e.g., #RRGGBB) or by a recognized color name (e.g., red).

-verbose
    Enables verbose output, causing srftopam to print detailed information about the conversion process, including input file characteristics and processing steps, to standard error.

file
    The path to the input Sun Rasterfile. If this argument is omitted, srftopam reads the image data from standard input, allowing for seamless integration into shell pipelines.

srftopam is a utility from the Netpbm suite designed to convert Sun Rasterfile (SRF) images into the Portable Arbitrary Map (PAM) format. The SRF format is an older image standard primarily associated with Sun workstations, while PAM is a modern, flexible, and extensible format within the Netpbm family. PAM can represent a wide array of pixel data, including arbitrary bit depths, multiple color planes (channels), and alpha transparency. This command is crucial for integrating legacy SRF images into contemporary image processing workflows that leverage the extensive toolkit of Netpbm. It efficiently handles various SRF types, including those with colormaps and grayscale data. By default, srftopam reads input from standard input if no filename is provided and writes the converted PAM image to standard output, making it highly suitable for command-line piping and scripting.

Sun Rasterfile Format Variations: The SRF format has numerous variations, including different sub-types and byte-ordering conventions. While srftopam is designed to handle most common SRF files, highly obscure, non-standard, or corrupted files may not convert correctly.

Gamma Interpretation: The interpretation of gamma correction information in SRF headers can sometimes be ambiguous or missing. This might lead to slight color shifts in the converted image if the -ignore_gamma option is not used and the header data is inaccurate.

Standard I/O Dependency: As a typical Netpbm tool, srftopam primarily uses standard input and standard output for data. Users must explicitly redirect output to a file if they wish to save the converted image to disk.

Like most tools in the Netpbm suite, srftopam is designed to operate seamlessly within command-line pipelines. It reads the Sun Rasterfile from standard input if no input file is specified and writes the resulting Portable Arbitrary Map (PAM) image to standard output. This design promotes modularity and allows for chaining multiple Netpbm commands together to perform complex image manipulation tasks.

srftopam is one of hundreds of specialized tools included in the comprehensive Netpbm collection. The suite is renowned for its adherence to the Unix philosophy: providing small, single-purpose utilities that can be combined (often via pipes) to achieve powerful and flexible image processing workflows. Understanding the broader Netpbm ecosystem enhances the utility of individual commands like srftopam.

srftopam is part of the Netpbm project, which evolved from Pbmplus, a set of image manipulation utilities created by Jef Poskanzer in the late 1980s. Netpbm significantly expanded Pbmplus's capabilities by adding support for more image formats and introducing new tools. The Portable Arbitrary Map (PAM) format itself was a later addition to the Netpbm suite, designed to offer greater flexibility and extensibility than the original Portable Anymap (PNM) formats (PBM, PGM, PPM). srftopam represents a more modern and robust conversion tool for Sun Rasterfiles compared to older, less flexible utilities like rasttopnm, aligning with the Netpbm philosophy of providing small, composable tools for image processing pipelines.

pam(5), pnm(5), rasttopnm(1), anytoppm(1), netpbm(1)