CMAP File

What are CMAP files and how to open them

Are you having problems opening a CMAP file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CMAP files.

What is a CMAP file?

CMAP files have multiple uses, and Adobe CMaps is one of them. Read more about the other uses further down the page.

Adobe CMaps

Adobe CMaps files are resources used in PostScript and PDF font systems to define how sequences of input bytes (character codes) map to glyph selectors in large, multilingual fonts. They are part of the CID-keyed font architecture, where one file (the CMap) defines encoding and mapping, and another (the CIDFont) holds the glyph shapes.

A CMap file maps input codes (single or multi-byte) to either CIDs (Character IDs), character names, or character codes, depending on use. It also defines a codespace (set of valid input byte sequences), the writing mode (horizontal or vertical), and declares which character set (charset) of a larger language collection is active. In the PDF format this map is used by Type 0 (composite) fonts; some CMaps provide mappings to Unicode values (via special ToUnicode CMaps) for extracting text or interoperability.

CMap files are plain PostScript-language programs. They include header comments defining version, name, registry, ordering, and supplement numbers; required operators such as begincmap and endcmap enclose the dictionary definitions; codespace ranges; range and single-code mapping operators (bfchar, bfrange, etc.). The specification for this format is Adobe Technical Note #5014, "Adobe CMap and CIDFont Files Specification".

How to open CMAP files

Important: Different programs may use files with the CMAP file extension for different purposes, so unless you are sure which format your CMAP file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 31, 2026

All known file formats using extension .CMAP

While Adobe CMaps is a popular type of CMAP-file, we know of 3 different uses of the .CMAP file extension. Different software may use files with the same extension for different types of data.

Concept Map File

The IHMC Cmap Tools software application uses the .cmap file suffix. This program is used to create mind-map diagrams for use during a brainstorming process. The brainstorming diagrams created with the software are saved with the .cmap file suffix.

CMAP opener for Windows

We have identified one CMAP opener that is compatible with this specific type of CMAP file.

IFF Color Map

IFF Color Map files store color palettes used in Amiga-style graphics that follow the ILBM (InterLeaved BitMap) section of the Interchange File Format. They are used to define how colors are displayed in indexed-color images and animations, where each pixel refers to a color by index rather than defining its color explicitly. This format is especially employed when graphics are created in the ILBM "FORM" of IFF: it allows the same color map to be shared, changed, or cycled separately from the image data.

The creator of this format is the authors of the EA IFF 85 standard (Electronic Arts in cooperation with Commodore-Amiga), which sets rules for IFF files using the ILBM FORM TYPE. When saving images or animations in ILBM, a CMAP section provides a list of color register entries (palette entries) that map index values to RGB colors. Programs that read IFF ILBM must use the CMAP chunk if present; if it is absent they fall back to a default palette or infer colors from other data. The number of colors normally matches 2ⁿ where n is the number of bitplanes specified in the image header; but fewer entries are allowed, and extra entries ignored. CMAP appears before the actual image data (BODY chunk) in a valid ILBM-formatted IFF file.

Internally, a color map chunk begins with the ASCII signatures FORM at offset 0 and ILBMCMAP at offset 8 identifying a FORM of type ILBM containing a CMAP chunk. The CMAP chunk stores 3n bytes: each set of three bytes gives the red, green, and blue intensities for one color register, with values ranging from 0 to 255. Color register 0 through n−1 correspond to these entries. If the listed number of bytes is odd, a pad byte is added (but not counted in the chunk size).

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Help us help others

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