Why Pixel information is in fraction returned by regionprops function.

Sir,am using regionprops function to find out the properties of elliptical structure. But it's Majojaxislength Minoraxislength and perimeter are in fractions. Why those fraction values? Is there any mathematical background to calculate these properties. Can you please help me.

Answer 1

[Walter Roberson]

regionprops says that the MajorAxisLength and MinorAxisLength will be in pixels. The definition for Perimeter is not as clear but the output is in pixels as well.

I think your question is perhaps why the results are not integers. The answer to that is that the lengths used are based upon the distance between pixel centers, which is an integer for horizontal and vertical distances but is not integer for angles.

   A
    B

distance between center of A and center of B is sqrt(1^2+1^2) = sqrt(2)

[Dhanu Naik]

Sir can you please provide mathematical background on which basis Majoraxislength and Minoraxislength functions are implimented using pixel information in matlab

[Walter Roberson]

See https://stackoverflow.com/questions/1532168/what-are-the-second-moments-of-a-region for a nice explanation.