clustering image, grayscale image

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Tomas 2014-3-15

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https://ww2.mathworks.cn/matlabcentral/answers/121704-clustering-image-grayscale-image

回答： Boni_Pl 2016-11-12

Hello, I have for example image

I want convert to grayscale image, and then use Kmeans method.

Does anyone help ?

Thanks.

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Image Analyst 2014-3-15

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https://ww2.mathworks.cn/matlabcentral/answers/121704-clustering-image-grayscale-image#answer_128585

Use rgb2gray() from the Image Processing Toolbox. Then kmeans() from the Statistical Toolbox. Here's a demo: http://www.mathworks.com/products/demos/image/color_seg_k/ipexhistology.html

I don't know what your question is, if any. And I'm having trouble matching your mindset. A gray level is a 2D image. Even if you plot it as a 2.5D surface where the height above the plane is the gray level, it's still a 2D image because there are two independent variables (row & column) and one dependent variable (the gray level). In 1D, if I had a vector [3,5,8,16,22] everyone says that's a 1D vector, not a 2D signal just because you could plot that values along the y axis and the index along the x axis. Or consider a sine wave - it's a 1D signal, not a 2D signal just because you plot it in the x,y plane.

I don't how you used kmeans. You simply have a colormap applied. You just say that if the gray level is less than about 64, make it red, and if it's between 64 and 145 it's green, and if it's greater than 145 it's blue. You don't need kmeans for that, you can use ind2rgb(). And I don't know what you did for the color image, for example did you use rgb2gray(), rgb2hsv() and use the v channel, or did you just take one of the color channels, or something else. Anyway, I'm not sure if you have a question or if we're done. I don't have the stats toolbox so I can't actually try any code with kmeans() in it.

Image Analyst 2014-3-16

Sorry I don't understand the language. I don't know what to click, and it started spewing out a bunch of stuff that I didn't know what it was into the command window. It went on for several minutes and I couldn't stop it, not even with control-C. I had to go into task manager to finally kill off MATLAB.

I suggest you try normal debugging operations to figure out what's going on.

Tomas 2014-3-16

编辑：Tomas 2014-3-16

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Never mind, my program works correctly only when clustering image It takes a long time.

I need, show my output.

I have output in cell.

for example Z= {1438x1} {5800x1} {425x1} {45x1}
in Z{1} is [48] [ 55] [46] ......
in Z{2} is [78] [ 89] [94].....
in Z{3} is [ 120] [ 134] [ 158]...
in Z{4} is [ 210] [ 248] [255].....