rawread

Read color filter array (CFA) image from RAW file

Syntax

cfaimage = rawread(filename)

cfaimage = rawread(filename,'VisibleImageOnly',visibleImageOnly)

Description

cfaimage = rawread(filename) reads a CFA image from the RAW image file specified by filename.

cfaimage = rawread(filename,'VisibleImageOnly',visibleImageOnly) specifies whether to read only the visible portion of the CFA or to read the entire CFA including the frame.

Examples

Read CFA Image Data from File

Read only the visible Color Filter Array (CFA) image data from a file. By default, rawread returns only the visible portion of the CFA image.

cfa = rawread("colorCheckerTestImage.NEF");

Read the entire CFA image from a file, including the image frame. In a RAW image, the frame is typically used to calculate the black-level surrounding the visible image.

cfa = rawread("colorCheckerTestImage.NEF", "VisibleImageOnly", false);

Input Arguments

filename — Name of RAW file

character vector | string scalar

Name of RAW file, specified as a string scalar or char vector. Specify filename as a full path, containing the file name and extension, or as a relative path from the current folder or from any folder on the MATLAB^® path.

Data Types: char | string

visibleImageOnly — Return only visible CFA image data

true (default) | false

Return only visible CFA image data, specified as a logical scalar true or false. In a RAW image, the frame is typically used to calculate the black-level surrounding the visible image. To read only the visible portion of the CFA, specify true. To read the entire CFA, including the frame, specify false. This table provides more detail for each option.

Value	Description
true	The dimensions of the cfaimage are VisibleImageSize(1)-by-VisibleImageSize(2)-by-P, where P is the number of planes. VisibleImageSize is a field in the ImageSizeInfo structure returned by rawinfo.
false	The dimensions of the cfaimage are CFAImageSize(1)-by-CFAImageSize(2)-by-P, where P is the number of planes. CFAImageSize is a field in the structure returned by rawinfo.

Data Types: logical

Output Arguments

cfaimage — CFA image

m-by-n-by-p numeric array

CFA image, returned as an m-by-n-by-p numeric array.

By default, rawread returns only the visible portion of the CFA image. In this case, the values of m and n correspond to the first and second elements of the VisibleImageSize field reported by rawinfo, respectively. If you choose to include the frame in the returned image, the values of m and n correspond to the first and second elements of the CFAImageSize field reported by rawinfo, respectively. For both types of returned images, the value of p depends on the type of CFA sensor. For Bayer type sensors, the value is 1. For a Foveon sensor, the value is 3.

Data Types: uint16 | single

Limitations

• The rawread function does not support RAW file formats that employ JPEG compression.

More About

RAW File Format

The RAW file format preserves image data in its most unedited state, recorded directly from the camera sensor. Most camera manufacturers define their own proprietary RAW file format, such as the Nikon NEF file format and the Canon CRW format. Adobe has also defined a RAW file format, DNG (digital negative), which is supported by several cameras. The name of the format is typically capitalized, like other file formats such as JPG and TIF. However, unlike other file formats, RAW is not an acronym.

Tips

• The function uses LibRaw version 0.20.2 for reading the CFA image data.