How to count the number of pixels from an image for specifies colors?

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Jotheeshwar V
Jotheeshwar V 2018-7-4
编辑： Jan 2019-6-11
I have used the code stated below.
if true
% code
imread color.jpg
load color.jpg
redChannel = color(:, :, 1);
greenChannel = color(:, :, 2);
blueChannel = color(:, :, 3);
whitePixels = redChannel == 255 & ...
greenChannel == 255 & ...
blueChannel == 255;
count = sum(whitePixels(:));
Red1Pixels = redChannel == 255 & ...
greenChannel == 166 & ...
blueChannel == 166;
count = sum(Red1Pixels(:));
Red2Pixels = redChannel == 254 & ...
greenChannel == 85 & ...
blueChannel == 82;
count = sum(Red2Pixels(:))
Blue1Pixels = redChannel == 179 & ...
greenChannel == 169 & ...
blueChannel == 250;
count = sum(Blue1Pixels(:))
Blue2Pixels = redChannel == 255 & ...
greenChannel == 255 & ...
blueChannel == 255;
count = sum(Blue2Pixels(:))
end
and I am getting error as below.
if true
% code
Index exceeds matrix dimensions.
Error in Try_03_07_2018 (line 17) greenChannel = color(:, :, 2); and Try_03_07_2018 is the file name.
Kindly help me out of this.
Regards,
Jotheeshwar V

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采纳的回答

Jan
Jan 2018-7-4
编辑：Jan 2018-7-4
Neither
imread color.jpg
nor
load color.jpg
import the pixels of the image to th variable color. Use this instead:
color = imread('color.jpg');
By the way: I'd expect load color.jpg to show an error already. So are you sure that your code run at all?

更多回答（2 个）

Image Analyst
Image Analyst 2018-7-4
Replace this
imread color.jpg
load color.jpg
with this
fileName = fullfile(pwd, 'color.jpg');
color = imread(fileName );
[rows, columns, numberOfColorChannels] = size(color);
if numberOfColorChannels < 3
errorMessage = sprintf('%s is not a color image!', fileName)
uiwait(errordlg(errorMessage));
return;
end
komal
komal 2019-6-7
After doing skin detection. I want to count the pixels of white region which indicates skin part shown in the image.How can I do it? Please help me out
  2 个评论
Image Analyst
Image Analyst 2019-6-7
numWhitePixels = nnz(skinMask);
where skinMask is your binary image that you get after doing the skin detection (which I assume you already know how to do that part).
Jan
Jan 2019-6-11
编辑：Jan 2019-6-11
@komal: Please do no append a new question in the section for answers of another thread. Ask a new question instead.
"Not working" is a lean description of our problem. Please mention any details. Of course you can use nnz to count elements in an array. So if something is not working for you, you have to explain, what the inputs are, what you want to achieve and what you get instead: a result which differs from your expectations, or an error message?
Afert opening a new thread, delete this pseudo answer here. Thanks.

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