Parallelization of a Loop with 'parfor - Unsuccessfully

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Royi Avital
Royi Avital on 13 Sep 2014
Commented: Matt J on 13 Sep 2014
Hello, I created an algorithm which work on Image Patches. I go through matrix of an image and apply a function of a neighborhood predefined.
For some reason MATLAB won't allow me using the 'parfor' command.
Here is the code:
mInputFrames = padarray(mInputFrames, [searchWinEffRadius searchWinEffRadius], 'replicate');
parfor iRowIdx = 1:videoFramesNumRows
for jColIdx = 1:videoFramesNumCols
paddedImageRowIdx = iRowIdx + searchWinEffRadius;
paddedImageColIdx = jColIdx + searchWinEffRadius;
vSearchWindowRowIdx = [(paddedImageRowIdx - searchWinEffRadius):(paddedImageRowIdx + searchWinEffRadius)];
vSearchWindowColIdx = [(paddedImageColIdx - searchWinEffRadius):(paddedImageColIdx + searchWinEffRadius)];
for kFrameIdx = 1:videoFramesNumFrames
vPatches = ((kFrameIdx - 1) * singleFrameSearchWindowNumPixels) + ...
mCurrSearchWindow = mInputFrames(vSearchWindowRowIdx, vSearchWindowColIdx, kFrameIdx);
mCurrSearchWindowPatches(:, vPatches) = Im2ColSliding(mCurrSearchWindow, [localWinSize, localWinSize]);
mOutputFrame(iRowIdx, jColIdx) = PatchFilter(mCurrSearchWindowPatches, refPixelRowIdx, refPixelColIdx, vGaussianKernel, weightsStd);
The error I'm getting: "The PARFOR loop cannot run due to the way variable 'mCurrSearchWindowPatches' is used.
The work on the loops is per pixel which is completely indepndent (In the result) from its neighborhood. What can I do to allow the parallelization to kick in?
Thank You.

Accepted Answer

Matt J
Matt J on 13 Sep 2014
Edited: Matt J on 13 Sep 2014
Pre-allocate mCurrSearchWindowPatches somewhere in the parfor loop but prior to the loop over kFrameIdx.

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