Problem 682. Image Processing 002 : Fix Vignetting in a Visible Sensor

Created by Richard Zapor

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{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","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\"?><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>The task is to correct image files for Visible scanning sensors that due to errant tolerancing produce vignetted(V) images. The V artifact is in a converging ray bundle and only the edges are impacted to differing amounts. The obscuration varies cross-scan but is constant for all samples. Sensor package repair is cost prohibitive. Luckily, the Image Processing is Matlab based and needs only a fast function to perform the V adjustment good enough for govt work.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Output: Fixed image(Fimg) (Array &lt;= 512x512 of type double)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Input: Vignetted Image file(Vimg) (double); Obscuration (1xncol)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Tolerance: Good enough is 1%+1 count of Truth (Timg)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Obscuration: Max is 25% at edge, Min 8 columns wide.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Vignetted Image creation: Start with Truth (Timg)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Vimg = Timg(1-Obscuration)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>example: Obs = [.25 .1 0...0 .1 .25]; obs [50 20 0...0 20 50];</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>load penny.mat; Timg=double(P);</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Vimg=Timg.*repmat(1-Obs,128,1)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>The Cody \"Image processing 001\" for an IR and using In-scene data was not intended to be so complex. This and its successor should have appeared prior to \"001\".</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>This Visible Vignetting correction is very direct.</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>"}]}

The task is to correct image files for Visible scanning sensors that due to errant tolerancing produce vignetted(V) images. The V artifact is in a converging ray bundle and only the edges are impacted to differing amounts. The obscuration varies cross-scan but is constant for all samples. Sensor package repair is cost prohibitive. Luckily, the Image Processing is Matlab based and needs only a fast function to perform the V adjustment good enough for govt work.Output: Fixed image(Fimg) (Array &lt;= 512x512 of type double)Input: Vignetted Image file(Vimg) (double); Obscuration (1xncol)Tolerance: Good enough is 1%+1 count of Truth (Timg)Obscuration: Max is 25% at edge, Min 8 columns wide.Vignetted Image creation: Start with Truth (Timg)Vimg = Timg(1-Obscuration)example: Obs = [.25 .1 0...0 .1 .25]; obs [50 20 0...0 20 50];load penny.mat; Timg=double(P);Vimg=Timg.*repmat(1-Obs,128,1)The Cody "Image processing 001" for an IR and using In-scene data was not intended to be so complex. This and its successor should have appeared prior to "001".This Visible Vignetting correction is very direct.

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