imapplymatrix

Linear combination of color channels

Syntax

Y = imapplymatrix(M,X)

Y = imapplymatrix(M,X,C)

Y = imapplymatrix(___,output_type)

Description

Y = imapplymatrix(M,X) computes the linear combination of the rows of M with the color channels of X.

Y = imapplymatrix(M,X,C) computes the linear combination of the rows of M with the color channels of X, adding the corresponding constant value C to each combination.

Y = imapplymatrix(___,output_type) returns the result of the linear combination in an array of type output_type.

Examples

Compute Linear Combination of Color Channels

This example shows how to create a grayscale image by computing the linear combination of three colors channels.

Read a truecolor image into the workspace.

RGB = imread('peppers.png');

Create a coefficient matrix

M = [0.30, 0.59, 0.11];

Compute the linear combination of the RGB channels using the coefficient matrix.

gray = imapplymatrix(M, RGB);

Display the original image and the grayscale conversion.

imshowpair(RGB,gray,'montage')

Input Arguments

M — Weighting coefficients for each color channel

q-by-p numeric array

Weighting coefficients for each color channel, specified as a q-by-p numeric array. p is the length of the third dimension of X. In other words, p=size(X,3). q is in the range [1,p].

X — Input image

m-by-n-by-p numeric array

Input image, specified as an m-by-n-by-p numeric array.

C — Constant to add to each channel

q-element numeric vector

Constant to add to each channel during the linear combination, specified as q-element numeric vector, where q is the number of rows in M.

Data Types: double

output_type — Output data type

'double' | 'single' | 'uint8' | 'uint16' | 'uint32' | 'int8' | 'int16' | 'int32'

Output data type, specified as one of the following: 'double', 'single', 'uint8', 'uint16', 'uint32', 'int8', 'int16', or 'int32'.

Data Types: char | string

Output Arguments

Y — Output image

numeric array

Output image comprised of the linear combination of the rows of M with the color channels of X, returned as a numeric array. If output_type is not specified, the data type of Y is the same as the data type of X.

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced in R2011b

R2022b: Support for thread-based environments

imapplymatrix now supports thread-based environments.