Graphics

Reading, Writing, and Querying Graphics Image Files

In its native form, a graphics file format image is not stored as a MATLAB matrix, or even necessarily as a matrix. Most graphics files begin with a header containing format-specific information tags, and continue with bitmap data that can be read as a continuous stream. For this reason, you cannot use the standard MATLAB I/O commands load and save to read and write a graphics file format image.

MATLAB provides special functions for reading and writing image data from graphics file formats. To read a graphic file format image use imread; to write a graphic file format image, use imwrite; to obtain information about the nature of a graphics file format image, use imfinfo.

This table gives a clearer picture of which MATLAB commands should be used with which image types.

Procedure	Function(s) to Use
Load or Save a Matrix as a MAT-file	load save
Load or Save Graphics File Format Image, e.g. BMP, TIFF	imread imwrite
Display Any Image Loaded Into MATLAB	image imagesc
Utilities	imfinfo ind2rgb

Summary of Image Types and Numeric Classes

Reading a Graphics Image