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From: Clare on 24 Nov 2009 01:45
Hi all. So recently I made the discovery that when use "imshow" command, the YDir parameter under Axis Properties is set to "reverse" by default. To me this seems counter intuitive. Why wouldn't YDir be "normal" by default? When set at "normal" it turns out that my image is actually flipped upside down.

On the contrary, when use "quiver" command to plot a vector field, the YDir is set at "normal" by default. Even though this makes more sense to me, because "reversed" YDir is the correct way to display an image (as in "imshow"), the result of "quiver" is that the vector fields this time depict the objects as if they are upside down... So every time I use "quiver" I always add the following line to revert the objects back to its normal orientation... set(gca, 'YDir', 'reverse')...

In addition, "plot" uses "normal" setting for YDir.

The only issue I have is that I use these commands fairly frequently in my job and sometimes they can get a little bit confusing in terms of display. So I wonder why MATLAB hasn't standardized them so that the objects always get displayed the same way. It's just a comment I have. Thank you.
From: Steven Lord on 29 Nov 2009 22:43

"Clare " <flyingclare(a)gmail.com> wrote in message
news:hefvdk$3md$1(a)fred.mathworks.com...
> Hi all. So recently I made the discovery that when use "imshow" command,
> the YDir parameter under Axis Properties is set to "reverse" by default.
> To me this seems counter intuitive. Why wouldn't YDir be "normal" by
> default? When set at "normal" it turns out that my image is actually
> flipped upside down.

In case anyone stumbles upon this thread in the future, Jan Simon explained
this in another thread Clare started.

http://www.mathworks.com/matlabcentral/newsreader/view_thread/266667

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ


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