how to use IPP to compare length between two photos?

Louis

Hi Yuri,

Could you kindly help to check whether we can use IPP to analysis hair growth on scalp?

Normally we take two pics. one is x-2D means fresh shaved area, another one is Tx means 2days after shaving. 

We wants:

1. length of each hair of shaved area (Tx-2D)

2. length of each hair of 2 days after shaved area (Tx)

3. each hair of the two picture need to be matched, so they can use length of hair after 2 days minus length of hair just shaved to see how long it grows. further to caluculate rate of Telogen hair. Telogen hair can be defined as grow less than 0.2mm of 2 days. (or 0.5mm it depends client)

4. thickness of each hair in Tx

5. number of hair

 We tried IPP fiber protocol to analyze, but met some difficulties.

Current difficulties in using IPP:

1. length analyzed using material seperate fiber protocol is not accurate enough. Hair is straight, but skeleton identified by software is curved.

2. each hair of two picture can't be match one by one.

3. thickness of hair analyzed using material thickness protocol is not accurate enough. Many hair can't be separated when they stick together.

I attached demo pics for your reference.  could you kindly help to finger a way to solve this?

Thanks a lot for your always strong support

Best

Louis

YuriG

Hi Louis,

The application is interesting, but it's not easy to implement the way you want.

First of all the image at different days are not aligned,  they are slightly distorted (since the skin is elastic) and shifted,. So, to find the match between the first and second hair they must be aligned. It can be done in Image-Pro using the "Image Compare" tool. You can add multiple registration points to match the hairs, like this (I converted images to Mono, inverted and applied tint before adding to image compare):
then the second image can be registered to the first using "Thin plate spline" transform (elastic):

and 2 images combined in color composite view to see the differences. On the image below the yellow color is for the matching hairs, the red is for the new, grown hear:

Then you can create a color image and segment red hairs (grown segments) using smart segmentation and report the average length :


This is a complex workflow, involves manual steps (adding registration lines) and it's the closest to your requirements. You can check if you can use it. 

Another option would be to measure the area of the hairs before and after and then find the difference in hair length by dividing the area by thickness (all hairs have the same thickness). It should give you similar results, but without complicated alignment steps.

Regards,

Yuri