Measure the length of the spiral object in the photo

Hi,

how can i measure the length of the spiral loop with image processing? The following is my input image.

[Jan]

How do you define "length"? This is not clear at the center.

[Pratheek Ullal]

The length is measured in mm along the inner or outer edge of each loop. the image shows the reference scale to measure the spiral loop.

[Pratheek Ullal]

Lenghth is measured in mm along the inner or outer edge of each loop in the spiral coil.