openframeworks / openframeworks/openFrameworks

ofxCvColorImage doesn't support RGBA images

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addon bug prelim-analysis
Dominant language
C++
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Description

Converting an ofImage(.. OF_IMAGE_COLOR_ALPHA) to an ofxCvColorImage using setFromPixels() corrupts the image data.
ofxCvColorImage::init() hard codes iplchannels to 3.
I added a quick fix for this by adding a setNumberOfChannels() method to ofxCvColorImage to change iplchannels to ofPixels::.getNumChannels() before calling allocate() or setFromPixels() and all works fine including converting the ofxCvColorImage back to an ofImage but this is not a great fix.

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at ofxCvColorImage::init() and trace the allocate() and setFromPixels() paths involved in converting an ofImage with OF_IMAGE_COLOR_ALPHA. Check how ofPixels::getNumChannels() relates to the hard-coded iplchannels value; done means RGBA image data converts without corruption and can be converted back to an ofImage.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, opencv
Domain
computer-vision
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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