how to set hue value of some pixel with opencv

Question

I need to change the hue of some pixels of my image, but i don't know how to set them!

I converted the image in HSV with CV_BGR2HSV and now i'm cycling with a for by rows and cols...

how can I access each pixel's hue?

for setting RGB i'm using this code...

CvScalar s;
s=cvGet2D(imgRGB,i,j); // get the (i,j) pixel value
printf("B=%f, G=%f, R=%f\n",s.val[0],s.val[1],s.val[2]);
s.val[0]=240;
s.val[1]=100;
s.val[2]=100;
cvSet2D(imgRGB,i,j,s); // set the (i,j) pixel value

Answer 1

Yes, openCV uses 180° i.e., (0°-179°) cylinder of HSV; while normally its (0°-240°) in MS paint and ideally (0°-360°). So, openCV gives you result of hue from (0°-179°).

Answer 2

You already converted your image to HSV, so the 3 layers of the image now correspond to Hue, Saturation and Value:

• s.val[0] is the hue.
• s.val[1] is the saturation.
• s.val[2] is the value.

So go ahead and use exactly the same method as for your RGB images to get and set the pixel values.