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CALS Raster File Format Information

What is a CALS Raster file

The CALS Raster file format was developed by the United States Department of Defense (DoD) as part of the Continuous Acquisition and Life-cycle Support (CALS) initiative. It was designed to provide a standardized way to store and exchange raster image data in technical and military documentation workflows. A CALS Raster file typically contains black-and-white raster images and may store the image data either uncompressed or compressed using CCITT Group 4 compression. Because of its efficient handling of monochrome images, the format has been widely used for scanned drawings, engineering documents, technical manuals, and archival imaging.


A CALS Raster file typically contains black-and-white raster images and may store the image data either uncompressed or compressed using CCITT Group 4 compression. Because of its efficient handling of monochrome images, the format has been widely used for scanned drawings, engineering documents, technical manuals, and archival imaging.


CALS Type 1 and Type 2

CALS Raster files are commonly categorized into Type 1 and Type 2, which define how image data is stored and encoded.

  • Type 1 (MIL-R-28002 Type I)
    Type 1 is the most widely used CALS format. It stores monochrome (black-and-white) raster images using CCITT Group 4 compression, making it highly efficient for scanned documents and technical drawings.
  • Type 2 (MIL-R-28002 Type II)
    Type 2 extends the CALS format by allowing additional flexibility in how image data is stored. It supports more variations in image encoding and structure compared to Type 1.

Typical uses of CALS files

CALS Raster files have commonly been used in:

  • Technical documentation
  • Engineering drawings
  • Military and aerospace documentation
  • Document archiving
  • Scanned monochrome image storage

Why CALS is still relevant

Although newer image and document formats are widely used today, CALS Raster files are still found in many organizations with legacy archives and established technical workflows. For this reason, reliable viewing, printing, and conversion of CALS files remains important.


View and convert CALS files

If you work with CALS Raster files, it is useful to have software that can open, view, print, and convert them to more common formats such as PDF, TIFF, PNG, or JPEG. This makes it easier to share archived content and integrate older documents into modern workflows.


Files in CALS format usually ends with a .cal extension.



CALS Viewing and Conversion Using Our Products

Most of our software products support conversion to and from the CALS format. You can convert a wide range of file formats to CALS, as well as convert CALS files to PDF and other commonly used formats.
ViewCompanion Pro and ViewCompanion Premium allow you to view, annotate, print, and convert CALS files with ease.
For developers, our SDK products—scViewerX SDK and scConverter SDK—provide full support for opening, viewing, and generating CALS files, making it easy to integrate CALS functionality into your own applications


With ViewCompanion Premium you can create searchable PDF files from CALS input.
If you need this functionality in your own application or workflow,consider using our scConverter SDK, which offers the same functionality for integration.