user08092013 user08092013 - 11 months ago 73
Objective-C Question

How to change a particular color in an image?

My question is if I have a Lion image just I want to change the color of the lion alone not the background color. For that I referred this SO question but it turns the color of whole image. Moreover the image is not looking great. I need the color change like photoshop. whether it is possible to do this in coregraphics or I have to use any other library.

EDIT : I need the color change to be like iQuikColor app

enter image description here

Answer Source

Here is the sketch of a possible solution using OpenCV:

  • Convert the image from RGB to HSV using cvCvtColor (we only want to change the hue).
  • Isolate a color with cvThreshold specifying a certain tolerance (you want a range of colors, not one flat color).
  • Discard areas of color below a minimum size using a blob detection library like cvBlobsLib. This will get rid of dots of the similar color in the scene.
  • Mask the color with cvInRangeS and use the resulting mask to apply the new hue.
  • cvMerge the new image with the new hue with an image composed by the saturation and brightness channels that you saved in step one.

There are several OpenCV iOS ports in the net, eg: I haven't tried this myself, but seems a good research direction.