How to convert an 8-bit OpenCV IplImage* to a 32-bit IplImage*?

Question

I need to convert an 8-bit IplImage to a 32-bits IplImage. Using documentation from all over the web I\'ve tried the following things:

// general code
img2 =         


        

Answer 1

The function you are looking for is cvConvertScale(). It automagically does any type conversion for you. You just have to specify that you want to scale by a factor of 1/255 (which maps the range [0...255] to [0...1]).

Example:

IplImage *im8 = cvLoadImage(argv[1]);
IplImage *im32 = cvCreateImage(cvSize(im8->width, im8->height), 32, 3);

cvConvertScale(im8, im32, 1/255.);

Note the dot in 1/255. - to force a double division. Without it you get a scale of 0.