Quantization HSV Space by assigning 8 level each to hue, saturation and value to give a quantized HSV space with 8x8x8=512 histogram bins

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shalaw faraj 2020-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/504603-quantization-hsv-space-by-assigning-8-level-each-to-hue-saturation-and-value-to-give-a-quantized-hs

评论： shalaw faraj 2020-3-25

采纳的回答： Subhadeep Koley

Hello,

I will try to quantize the HSV color space but I can not, can anyone help me please?

I want to Quantization HSV Space by assigning 8 level each to hue, saturation and value to give a quantized HSV space with 8x8x8=512 histogram bins.

Thanks

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Subhadeep Koley 2020-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/504603-quantization-hsv-space-by-assigning-8-level-each-to-hue-saturation-and-value-to-give-a-quantized-hs#answer_414810

编辑：Subhadeep Koley 2020-2-14

在 MATLAB Online 中打开

Here is an example of quantization of the HSV colorspace

clc; close all;
rgbImage = imread('peppers.png');
hsvImage = rgb2hsv(rgbImage);
montage(hsvImage,'Size', [1, 3]); title('Before Quantization'); colorbar;
threshRGB = multithresh(hsvImage, 8);
threshForPlanes = zeros(3, 8);
for i = 1:3
threshForPlanes(i, :) = multithresh(hsvImage(:, :, i), 8);
end
quantPlane = zeros(size(hsvImage));
for i = 1:3
    value = [0 threshForPlanes(i, 2:end) 1]; 
    quantPlane(:, :, i) = imquantize(hsvImage(:, :, i), threshForPlanes(i, :), value);
end
quantPlane = double(rescale(quantPlane, 0, 1));
figure; montage(quantPlane, 'Size', [1,3]); title('After Quantization'); 
colormap(parula(8)); colorbar;

Hope this helps!

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Subhadeep Koley 2020-2-15

在 MATLAB Online 中打开

@ shalaw faraj I have been able to reproduce the same issue in R2017b, earlier I was trying it in R2019b.

It seems it is a problem of the function montage, which is not scaling the images properly (this issue is addressed in later releases). However you can use subplot instead of montage. Refer the code below.

Hope this helps!

clc; close all;
rgbImage = im2double(imread('peppers.png'));
hsvImage = rgb2hsv(rgbImage);
figure('Name', 'Before Quantization',...
    'units','normalized','outerposition',[0 0 1 1]);
subplot(1, 3, 1); imshow(hsvImage(:, :, 1)); colorbar;
subplot(1, 3, 2); imshow(hsvImage(:, :, 2)); colorbar;
subplot(1, 3, 3); imshow(hsvImage(:, :, 3)); colorbar;
threshRGB = multithresh(hsvImage, 8);
threshForPlanes = zeros(3, 8);
for i = 1:3
    threshForPlanes(i, :) = multithresh(hsvImage(:, :, i), 8);
end
quantPlane = zeros(size(hsvImage));
for i = 1:3
    value = [0 threshForPlanes(i, 2:end) 1];
    quantPlane(:, :, i) = imquantize(hsvImage(:, :, i), threshForPlanes(i, :), value);
end
quantPlane = double(rescale(quantPlane, 0, 1));
figure('Name', 'After Quantization',...
    'units','normalized','outerposition',[0 0 1 1]);
subplot(1, 3, 1); imshow(quantPlane(:, :, 1)); colormap(gca, parula(8)); colorbar;
subplot(1, 3, 2); imshow(quantPlane(:, :, 2)); colormap(gca, parula(8)); colorbar;
subplot(1, 3, 3); imshow(quantPlane(:, :, 3)); colormap(gca, parula(8)); colorbar;