pamtofits

Convert a Netpbm image to the FITS format

$ pamtofits [path/to/image.pam] > [path/to/output.fits]

pamtofits [options] [input_pam_file]

If input_pam_file is not specified, pamtofits reads from standard input. Output is always written to standard output.

-t bitpix
    Specifies the number of bits per pixel for the FITS output. Common values include 8, 16, 32 (for integers) or -32, -64 (for floating point numbers).

-b bscale
    Sets the FITS BSCALE keyword, used for linear scaling of pixel values.

-z bzero
    Sets the FITS BZERO keyword, used as an offset for pixel values in combination with BSCALE.

-e extname
    Sets the FITS EXTNAME keyword for the image extension, providing a descriptive name for the HDU (Header Data Unit).

-H header_file
    Reads additional FITS header keywords from the specified header_file and includes them in the output FITS header.

-V val_type
    Specifies the pixel value type, such as unsigned_char, signed_short, float, or double, influencing how pixel data is stored.

-q quant_level
    Quantizes the data to a specific number of levels, useful for reducing file size or adapting data to specific FITS bit depths.

-v verbose_level
    Controls the verbosity of output messages, with levels typically ranging from 0 (silent) to 3 (detailed debugging information).

-T
    Transposes the image data, effectively swapping the X and Y axes of the image.

-W
    Suppresses all warning messages that might be generated during the conversion process.

-N
    Outputs a simple FITS primary header only, without any extensions or complex FITS structure, potentially improving compatibility with older FITS readers.

pamtofits is a utility from the Netpbm project, a comprehensive toolkit for image manipulation. It specializes in converting images from the Portable Arbitrary Map (PAM) format to the Flexible Image Transport System (FITS) format. The PAM format is Netpbm's most versatile, supporting arbitrary-depth images and various color models. FITS, on the other hand, is a widely adopted standard in astronomy for storing scientific data, including images, spectra, and tables, designed for long-term archival and interoperability.

pamtofits reads a PAM image from standard input (or a specified file) and outputs the corresponding FITS image to standard output. This makes it an essential tool for astronomers and scientists who need to integrate Netpbm-processed images into their FITS-based workflows, ensuring proper data representation and adherence to the FITS standard.

FITS is primarily designed for scientific data; while pamtofits handles image data, complex scientific datasets might require more specialized FITS tools for full metadata integration.

The conversion fidelity depends on the input PAM image's characteristics. Not all PAM features map directly or optimally to FITS, and some transformations (e.g., color conversion, quantization) might result in data loss or alteration.

FITS files, especially for high bit-depth or multi-dimensional data, can be very large. Ensure sufficient disk space and consider the implications for data transfer and storage.

pamtofits typically reads its input PAM image from standard input if no file argument is provided. The resulting FITS image is always written to standard output. This design makes it highly suitable for use in shell pipelines, allowing chaining with other Netpbm utilities or command-line tools for complex image processing workflows.

The command strives to produce FITS files that are compliant with the FITS standard (currently FITS v4.0). Users working with specific FITS processors or requiring strict compliance should consult the FITS standard documentation and potentially use options like -O (Output standard FITS only) or -N (Simple FITS header) to ensure maximum compatibility with their target systems or applications.

pamtofits is a component of the Netpbm suite of graphics utilities, which originated from the PBMPlus package by Jef Poskanzer in the late 1980s. PBMPlus laid the groundwork with the Portable Bitmap (PBM), Graymap (PGM), and Pixmap (PPM) formats. The Netpbm project expanded upon this, introducing the more flexible Portable Arbitrary Map (PAM) format to handle arbitrary depths, planes, and transparency.

The development of pamtofits specifically addresses the need to bridge Netpbm's general image processing capabilities with the specialized requirements of the FITS format, a cornerstone in astronomical and scientific imaging. It allows researchers to leverage Netpbm's extensive tools for image manipulation and then seamlessly convert their data into a FITS-compliant format for analysis and archival, effectively superseding older, less capable converters like pnmtofits.

pam(5), fitstopam(1), netpbm(1), pnmtofits(1)