Colour Quantization
Does anyone know if there are any Colour Quantization (Colour Reduction) methods in OpenCV?
If so, could you please guide me to where it is? Or anyone else that has implemented it using OpenCV?
Does anyone know if there are any Colour Quantization (Colour Reduction) methods in OpenCV?
If so, could you please guide me to where it is? Or anyone else that has implemented it using OpenCV?
for color quantization without number of color you can use cvPyrMeanShift else quantization with number of color you can use cvKmean.In the KMean method the number of clusters is equal to number of the output colors and convert the input image rows/columns as a set of 1D vectors with 3 component(RGB).You have to use KMean in 3D instead of 2D. For quantization by KMean use the below code.
void bhQuantizeImage(IplImage* srcImage,IplImage* dstImage,int colorCount)
{
int i, size;
CvMat *clusters;
CvMat *points;
CvMat *color = cvCreateMat (colorCount, 1, CV_32FC3);
CvMat *count = cvCreateMat (colorCount, 1, CV_32SC1);
size = srcImage->width * srcImage->height;
dstImage = cvCloneImage (srcImage);
clusters = cvCreateMat (size, 1, CV_32SC1);
points = cvCreateMat (size, 1, CV_32FC3);
for (i = 0; i < size; i++) {
points->data.fl[i * 3 + 0] = (uchar) srcImage->imageData[i * 3 + 0];
points->data.fl[i * 3 + 1] = (uchar) srcImage->imageData[i * 3 + 1];
points->data.fl[i * 3 + 2] = (uchar) srcImage->imageData[i * 3 + 2];
}
cvKMeans2 (points, colorCount, clusters, cvTermCriteria (CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 10, 1.0));
cvSetZero (color);
cvSetZero (count);
for (i = 0; i < size; i++) {
int idx = clusters->data.i[i];
int j = ++count->data.i[idx];;
color->data.fl[idx * 3 + 0] = color->data.fl[idx * 3 + 0] * (j - 1) / j + points->data.fl[i * 3 + 0] / j;
color->data.fl[idx * 3 + 1] = color->data.fl[idx * 3 + 1] * (j - 1) / j + points->data.fl[i * 3 + 1] / j;
color->data.fl[idx * 3 + 2] = color->data.fl[idx * 3 + 2] * (j - 1) / j + points->data.fl[i * 3 + 2] / j;
}
for (i = 0; i < size; i++) {
int idx = clusters->data.i[i];
dstImage->imageData[i * 3 + 0] = (char) color->data.fl[idx * 3 + 0];
dstImage->imageData[i * 3 + 1] = (char) color->data.fl[idx * 3 + 1];
dstImage->imageData[i * 3 + 2] = (char) color->data.fl[idx * 3 + 2];
}
cvReleaseMat (&clusters);
cvReleaseMat (&points);
cvReleaseMat (&color);
cvReleaseMat (&count);
}
Thanks for the detailed answer. If possible though; can some documentation be added to the code to highlight the key tasks for further elaboration?
Asked: 2012-12-18 09:36:11 -0600
Seen: 6,636 times
Last updated: Dec 19 '12
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