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image-processingfilterimage-manipulationjpeg

Hide part of image

I have an image in jpg format. I want to apply image effect on a rectangle inside image. the effect should do something that human could not recognize what is behind the image. the effect should have the reversibility capability so when someone applying the effect and send me the image I apply another filter on it and get the original picture.

another part of image (whole image except that rectangle (rectangle size and position is known in both filtering and defiltering process)) should not be modified and should be recognizable by human.

an example would be hiding human face in an image in a way other part of image are still visible.

the problem is:

  1. image is in jpg form and I am not allowed to change the format, so jpg compression and other issues with jpg format make some troubles.
  2. I just get the image and I should apply filter and overwrite it, the source picture should not be stored.
  3. which filter should I use? I have some Image processing knowledge and I can use OpenCV and Aforge. and the effect shouldn't be checkboarding!
Solution

  • Does it need to be a pixel transformation? Could you just redact the rectangle (turn all pixels to black) and store the original in meta-data in the JPEG? You could even encrypt it. You would have a perfect version of it, and anyone looking at the image wouldn't be able to see it.