How to store the gray level pixel values into a 2-D array?

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Durga 2015-4-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/213543-how-to-store-the-gray-level-pixel-values-into-a-2-d-array

评论： Durga 2015-4-25

采纳的回答： Stephen23

In MATLAB,images are stored in a 1-D array....how to put them into a 2-D array?

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Stephen23 2015-4-25

编辑：Stephen23 2015-4-25

Can you show any documentation that states that "In MATLAB,images are stored in a 1-D array." ?

All the documentation that I have ever read states that images are stored as m*n or m*n*3 arrays:

http://www.mathworks.com/help/matlab/ref/imread.html#outputarg_A

http://www.mathworks.com/help/matlab/ref/ind2rgb.html

http://www.mathworks.com/help/matlab/creating_plots/image-types.html

http://www.mathworks.com/help/matlab/ref/rgb2gray.html

If you have an image in a "1-D array" then this is certainly not due to using the inbuilt MATLAB image functions, and you will need to show us your code so that we can see what you are doing.

Durga 2015-4-25

Actually i want to do substract one image from another(substract their pixel values and store them into a 2-D array.And then finding the Median value from the difference matrix. So,at first i was jst storing the value of the images:

val=img1(); val1=img2();

I culd not do it via 2-D operations,so i thought it is done via 1-D operations..

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Answer 1

Stephen23 2015-4-25

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https://ww2.mathworks.cn/matlabcentral/answers/213543-how-to-store-the-gray-level-pixel-values-into-a-2-d-array#answer_176672

编辑：Stephen23 2015-4-25

在 MATLAB Online 中打开

If the images are the same size then you can simply subtract the arrays directly:

A = imread(filenameA);
B = imread(filenameB);
D = A-B;

This works because in MATLAB many operations are vectorized, which means they operate on the whole array all at once. If the images are different sizes then you will need to resize one or both of them before performing this subtraction. You could use imresize for this.

And then use median note that the image data is going to be 2D or 3D depending on the image type, so to get the median of all values you will need to convert the array to a vector first:

median(D(:))

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Durga 2015-4-25

Thanks Sir. using D=A-B is correct for this method and i have got the difference 2-D array.

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Answer 2

Jan 2015-4-25

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https://ww2.mathworks.cn/matlabcentral/answers/213543-how-to-store-the-gray-level-pixel-values-into-a-2-d-array#answer_176658

No, gray level images are stored in 2D array in Matlab in general.

Please explain, why you assume that they are stored in 1D-vectors. This assumption seems to be the problem.

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Durga 2015-4-25

编辑：Durga 2015-4-25

Actually i want to do substract one image from another(substract their pixel values and store them into a 2-D array.And then finding the Median value from the difference matrix. So,at first i was jst storing the value of the images:

val=img1(); val1=img2();

I culd not do it via 2-D operations,so i thought it is done via 1-D operations..