How to find the length of an object in an image?

Hi,

I am new to image processing and I am looking for a way to find the length in cm of an object in an image. In particular, I am dealing with images of human body segments like feet, hands etc.

Thanks

[SUBASHINI N]

i don't know to find length of an image in matlb can you explain

Answer 1

[Image Analyst]

You can use regionprops. See a Image Segmentation Tutorial demo in my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862.

Also see VisionBib http://www.visionbib.com/bibliography/contents.html to find papers on body part segmentation.

[Brahm]

Hi Image Analyst, with your help I have gotten to the point of obtaining perimeter and area of the surface of objects I need.

But, how do i convert the area from number of pixels to cm^2 and in what units does matlab calculate the perimeter and how can you convert the perimeter into cm?

[Image Analyst]

It's all in pixels. To get into some other units you need to multiply by the spatial calibration factor. Measure something of known length, say 1 meter. Then see how many pixels it is. Divide the two and you have your factor. See attached demo.