Reading Remote Sensing Data in IMG Format

In remote sensing algorithm research, the IMG format serves as a common raster data storage format, typically accompanied by an HDR header file containing geospatial information and band parameters. MATLAB, as a scientific computing tool, can efficiently process this type of remote sensing data.

The core reading process involves three key steps: First, parse the HDR header file to extract metadata such as row/column counts and data types using MATLAB's textscan function, which efficiently reads key-value pairs line by line. Second, open the IMG file in binary mode using fopen and fread functions, paying special attention to byte order (big-endian/little-endian) which must match the header file specifications. Third, reshape the binary stream into a 3D matrix according to band count and data type (e.g., uint16/int32) from the header, then use permute function to adjust dimension order to conform to standard remote sensing data arrangement (rows, columns, bands).

For multispectral or hyperspectral data, it's recommended to encapsulate the data into structures integrating reflectance values, geographic coordinates, and wavelength information. IMG files generated by ENVI software may contain three storage layouts (BSQ/BIP/BIL), requiring specific data reorganization logic during reading that accounts for interleave patterns.