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.

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

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

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