Getting pixel values from an image

2016 7 22
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更新时间：2016 7 24
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Hello, I am new to Matlab and I have a question concerning getting pixel values of an image. I have a 994x994 image and want to get every pixel value in the row 497. Could you please advise what command(s) I should use? Thank you very much.
I have loaded the image in Matlab with Imtool command and there is a pixel region window in which it shows all the pixel values I need. I am wondering if I could export them in an excel file? Thanks again.
Regards

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Thorsten
Thorsten 2016-7-22
编辑：Thorsten 2016-7-22

2 个投票

If your image is stored in I, like from the command
I = imread('peppers.png');
the Matlab syntax to select the element in row 497, column 1 would be
x = I(497,1);
and the syntax to select all elements uses the column operator : as a shorthand for 1:end
x = I(497, :);

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Gannian Zhang
Gannian Zhang 2016-7-22
Thank you very much for your reply.
Could you please expand a little on your answer as I do not get what you say here? Thank you very much.
Regards
Thorsten
Thorsten 2016-7-22
I've updated my response.
Gannian Zhang
Gannian Zhang 2016-7-24
Hi Thanks so much for the explanation. I have finally solved this problem. :-)

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Azzi Abdelmalek
Azzi Abdelmalek 2016-7-22

2 个投票

You can use imread to import your image like this
Im=imread('YourImage.tif') % for example
row497=Im(497,:,:)
You can export your image to an excel file
xlswrite('file.xlsx',Im)

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Gannian Zhang
Gannian Zhang 2016-7-22
编辑：Azzi Abdelmalek 2016-7-22
Thank you very much for your reply.
I see. Now I get the idea. If I may, I wish to ask another quick question about using the 'imread' command. Here is what I did following your advice.
RGB = imread('image.tif');
I = rgb2gray(RGB);
Greyimage = imread(I); (But the command here did not work);
Also could you please tell me how I could do this:
row497 = Greyimage(497,i);
I wish to ask Matlab to export all the data from i=1 to i=997.
Thanks again for your kind help.
Regards
Azzi Abdelmalek
Azzi Abdelmalek 2016-7-22
What is the aim of this: Greyimage = imread(I) ? I is not a file, it's already a matrix representing an image.
Gannian Zhang
Gannian Zhang 2016-7-24
Hi, thanks for your reply.
The original image was a coloured one which had three channels showing different pixel values. I wanted to convert it into a grey image first before analysis.
Could you please let me know how to do that? And how can I export data from i=1 to i=997 please? Regards.
Gannian Zhang
Gannian Zhang 2016-7-24
Hi Thank you for your help. I have finally solved the problem.

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