Image Processing Toolbox™

ind2gray - Convert indexed image to grayscale image

Syntax

I = ind2gray(X,map)

Description

I = ind2gray(X,map) converts the image X with colormap map to a grayscale image I. ind2gray removes the hue and saturation information from the input image while retaining the luminance.

Note   A grayscale image is also called a gray-scale, gray scale, or gray-level image.

Class Support

X can be of class uint8, uint16, single, or double. map is double. I is of the same class as X.

Examples

load trees
I = ind2gray(X,map);
imshow(X,map)
figure,imshow(I)

Algorithm

ind2gray converts the colormap to NTSC coordinates using rgb2ntsc, and sets the hue and saturation components (I and Q) to zero, creating a gray colormap. ind2gray then replaces the indices in the image X with the corresponding grayscale intensity values in the gray colormap.

See Also

gray2ind, imshow, imtool, rgb2ntsc

imwrite

ind2rgb