Reverse the y-data in Matlab

No longer needed.

Answer 1

[Image Analyst]

Is this what you mean?

flippedImage = flipud(originalImage);

[Azzi Abdelmalek]

Make it clear by posting the expected result

[Image Analyst]

Where are you plotting this data? Over the image itself, or in a different plot? If in a different plot, try this

set(gca, 'ydir', 'reverse');