issue in converting matrix to rgb image

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PRACHI Sood 2020-4-3

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https://ww2.mathworks.cn/matlabcentral/answers/515027-issue-in-converting-matrix-to-rgb-image

评论： PRACHI Sood 2020-5-12

I was trying to replace pixel values by their corresponding 3x3 non overlapping block. since the output matrix was of type double I converted it to uint8 type.

But when I displayed the image in the figure window it was gray instead of coloured image . I tried cat(3, gray, gray, gray) but image is still colourless.

What did I do wrong?

 img= imread('C:\Users\prach\MATLAB programs\Lenna_(test_image).png');
 new = blockproc(img, [10 10], fun);
 new1= uint8(new);
 imshow(new1)
 rgbnew= cat(3, new1, new1, new1);
 imshow(rgbnew)

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Walter Roberson 2020-5-11

在 MATLAB Online 中打开

sounds like you are using a slightly older version of MATLAB that does not permit multiple dimensions. In that case as long as the image grayscale, median(block_struct.data(:))

But if you are dealing with rgb then it gets a bit messier,

median(reshape(block_struct.data,[],1,3),1)

PRACHI Sood 2020-5-12

@Walter Roberson

The median(block_struct.data(:)) worked perfectly. Thankyou very much.

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回答（1 个）

Image Analyst 2020-5-10

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https://ww2.mathworks.cn/matlabcentral/answers/515027-issue-in-converting-matrix-to-rgb-image#answer_431610

You need to use imsplit() to get the individual color channels, and then process them and combine them with cat(3).

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Image Analyst 2020-5-11

blockproc_color_means.m

The blockproc_color_means.m demo gives this image. Is it like you want?

PRACHI Sood 2020-5-12

Apologies for the incomplete information. Attaching the .m file and the image.

Yes, the output images shown in your last comment as output of blockproc_color_means.m is my desired output. I will go through the list of demos you have provided. Thankyou very much.

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