Image and data matrices

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med-sweng 2014-1-1

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评论： Wayne King 2014-1-1

When I read some image in `MATLAB`, do we say that this image is also a data matrix? Or, they are two different things? If they are different, how can we convert an image to a data matrix in MATLAB?

As far as I know, an image is a matrix of pixels, isn't it?

Thanks.

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Answer 1

Wayne King 2014-1-1

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编辑：Wayne King 2014-1-1

在 MATLAB Online 中打开

Yes, to MATLAB an image is just a matrix of values. Whether a matrix actually represents an image of course depends on the arrangement of values in the image.

For example:

    X = randn(256,256);
    imagesc(X); colormap gray;

is an image, but we don't recognize it as something as meaningful as opposed to (another very simple example)

   X = eye(256);
   Y = flipud(X);
   Z = X+Y; Z(128,128) = 1;
   imagesc(Z); colormap gray;

But to MATLAB, both are the same.

Now certainly, there are some data matrices which have dimension and datatype combinations that are usually found just with images. For example, if you see a MxNx3 matrix with elements that are of the datatype unit8, that is almost always an image.