MATLAB: “imshow” distorts jpeg

.jpgguiimshowMATLAB

I am using the following code to display an image on an axis in a Matlab GUI.

axes(handles.axis1);
imshow('my_image.jpg');

This is distorting my image. (There is text on the image which becomes difficult to read). However it seems that Matlab is trying to keep the dimension ratio, because stretching the axis in one direction does not change the output of imshow at all.

I have tried using XData and YData to manually resize the jpeg, with limited success. If I open the jpeg directly, it looks perfect, so it must be something Matlab is doing.

Does anyone have any suggestions? I don't really have a firm grasp on what Matlab is doing when I call the imshow function, so please point out of I'm completely off-base. Thanks.

-Matt

Best Answer

It "shrinks to fit" the image into your axes. This means that it might subsample your image and lose some pixels, causing it to look bad. Try using a bigger axes, or maybe you can play around with the 'InitialMagnification' option for imshow(), or try using zoom().

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MATLAB: Can’t MATLAB resize an image nicely

Would you please provide some code as to how you are displaying, resizing, and exporting the data from MATLAB so that we can better understand what you are trying to do?

One thing I would try is that I suspect you are using image/imagesc instead of imshow to display that data. If you aren't careful with the data aspect ratio in your axes, this will distort the text in display. If you cannot use imshow (IPT dependency), try this:

A = imread('http://www.antigrain.com/research/font_rasterization/msword_text_rendering.png');
image(A)
truesize

This will display your data at the original aspect ratio, which is definitely something you need when working with text.

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If you must use imshow(), then skip the axes() call and use

imshow(f, 'Parent', handles.axes1);

However, if you do not need imshow() specifically (e.g., you do not need the tools that it adds), then use

imagesc(f, 'Parent', handles.axes1);

Best Answer

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