How can I calculate the area of an irregular shape from a picture in jpeg?

Question

I have taken a picture of a shape with my camera. I need to calculate the area of that shape. Is there any software that can do that? I have the scale. Thanx!

Answer 1

You need to do it the slow manual way.

Transpose it to piece of graph paper.

Two methods. Draw it accurately on graph paper and count the blocks.

Or break it up into triangles and rectangles and calculate the area of each, and add.

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Answer 2

Could be a job for imageJ (free at http://rsbweb.nih.gov/ij/)

irregular arrea selection then menu analyze measure

Answer 3

Count the number of pixels in the area, by blowing the picture up.

You can determine the number of pixels per inch, and should be able to work out the area.

Answer 4

You can also do it by weighing the paper.

1st weigh the whole paper (wt = W1)

2nd = carefully cut out the photo and weigh it (W2)

Let us say area of the whole paper was A,

then area of photo = A X W2/W1