Problem 2542. Convert a grayscale image into RGB colour format, preserving data type

Created by John

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{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>In the Image Processing Toolbox, MATLAB provides</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[rgb2gray]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>to convert a 3 channel color image into a 1 channel intensity (grayscale image). But not the other way around. Sometimes it is useful to have an intensity image represented in the 3 channel colour format.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Write a function to convert an input grayscale image into an equivalent RGB image, ensuring that the datatype of the input image matrix is preserved.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Example:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[grayImg = [1 2 3; 4 5 6; 7 8 9];\nrgbImg = gray2rgb(grayImg);\nrgbImg(:,:,1) = [1 2 3; 4 5 6; 7 8 9];\nrgbImg(:,:,2) = [1 2 3; 4 5 6; 7 8 9];\nrgbImg(:,:,3) = [1 2 3; 4 5 6; 7 8 9];]]></w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

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39 Solutions
24 Solvers

Last Solution submitted on Dec 30, 2020

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Guillaume on 2 Sep 2014

Really, you need to add more test cases. You're not even testing that your condition of 'ensuring that the datatype of the input image matrix is preserved' has been fulfilled.

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