CODEWITHSUNDEEP
c++image-processingopencv
Mike
Mike

Reputation: 113

Contrast stretching an image by openCV

I'm trying to stretch the contrast of an image to the range of 0-255 using cvNormalize. But when I print out the output pixel values, Some negative numbers appear as the pixel value. I appreciate if you help me find out where the origin of the problem is. This is the code:

cvNormalize(srcImage, dstImage, 0, 255, CV_MINMAX );

for ( int pixel = 0; pixel < dstImage->height * dstImage->width; pixel++ ) {
    printf("%d\t",*(dstImage->imageData + pixel));
}

Upvotes: 4

Views: 6780

Answers (1)

ArtemStorozhuk
ArtemStorozhuk

Reputation: 8725

Because imageData's type is char* and char can be nagative (range is [-128, 127]). Try casting to unsigned char.

See docs.

Upvotes: 4

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