# Documentation

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# 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 from C to each combination.

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

## Input Arguments

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Weighting coefficients for each color channel, specified as a numeric array. If X is size m-by-n-by-p, M must be size q-by-p, where q is in the range [1,p]. M must be type double.

Data Types: double

Input image, specified as a numeric array of size m-by-n-by-p.

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

Data Types: double

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

## Output Arguments

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

## Examples

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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.

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')