y position of a rectangle drawn over an image compared to axes

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ChiPhi85 2019-2-17

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回答： Walter Roberson 2019-2-17

In the documentation, it states for drawrectangle or rectangle that the position of a rectangle is given by [xmin ymin width height].

If you plot a rectangle over axes, the ymin seems to correspond to the minimum y position from the bottom, but if you do it over an image it appears that the ymin is from the top of the image. Is this correct? Is there a reason for this?

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Answer 1

Walter Roberson 2019-2-17

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Depending on the state of the axes (hold on or not) and the image drawing function you use, it is common for the image drawing functions to automatically set YDir to 'reverse', because it is common that people want (1,1) of the data array to correspond to the top left corner.