How to extract colour descriptor (set of features) from the image?
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Andrew Tim
on 3 Jul 2015
Commented: nissrine Neyy
on 23 Jan 2021
Hello, I have the following task. I want to compute the color histogram of an Image in HSV color space. For that I want to uniformly quantize the HSV color space into 240 cubes in which the quantization of each channel is 15 hues (H), 4 saturations (S) and 4 intensities (V ) respectively. And after making this color histogram the values of each bin is my 240 dim vector of color features which I want to get finally. Could someone please help me with the m-code for this task or with the high level plan how to create it? I will really appreciate it. Thank you.
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Accepted Answer
Image Analyst
on 3 Jul 2015
Loop over every pixel in the image and determine the bin, then increment the count. Here's a start
[rows, columns, numberOfColorChannels] = size(rgbImage);
hsvImage = rgb2hsv(rgbImage); % Ranges from 0 to 1.
hsvHist = zeros(15,4,4);
for col = 1 : columns
for row = 1 : rows
hBin = floor(hsvImage(row, column, 1) * 15);
sBin = floor(hsvImage(row, column, 2) * 4);
vBin = floor(hsvImage(row, column, 3) * 4);
hsvHist(hBin, sBin, vBin) = hsvHist(hBin, sBin, vBin) + 1;
end
end
17 Comments
Image Analyst
on 23 Jan 2021
nissrine, note that an array defined as zeros(n1, n2, n3) is always a 3-D array regardless of what the values of n1, n2, and n3 are.
Now h, s, and v are basically continuous variables in the range of 0-1 and the poster wanted to divide the range of h into 16 bins and s and v into 4 bins.
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