Convert RGB color image to grayscale.

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Oah Joan 2018-11-16

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https://ww2.mathworks.cn/matlabcentral/answers/430350-convert-rgb-color-image-to-grayscale

编辑： John Kelly 2021-1-15

How do I write a function rgb2luma(colourimage) that converts an RGB colour image to a grayscale one based on “luma” defined as Y = 0.2126 R + 0.7152 G + 0.0722 B. I also want to normalize the result so that Y is in the range [0 1].

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Stephen23 2020-11-20

编辑：John Kelly 2021-1-15

Original question on 16 Nov 2018

Convert RGB color image to grayscale.

How do I write a function rgb2luma(colourimage) that converts an RGB colour image to a grayscale one based on “luma” defined as Y = 0.2126 R + 0.7152 G + 0.0722 B. I also want to normalize the result so that Y is in the range [0 1].

Rena Berman 2021-1-15

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Answer 1

Image Analyst 2018-11-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/430350-convert-rgb-color-image-to-grayscale#answer_347422

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Try this:

% Sample call
% colourimage = imread('peppers.png');
% Y = rgb2luma(colourimage);
% imshow(Y);
function Y = rgb2luma(colourimage)
R = double(colourimage(:, :, 1)); % Extract red channel.
G = double(colourimage(:, :, 2)); % Extract green channel
B = double(colourimage(:, :, 3)); % Extract blue channel.
Y = 0.2126 * R + 0.7152 * G + 0.0722 * B;
Y = Y / max(Y(:));
end