Measuring facial features.......

Owlface23 · **Joined:** Mar 30, 2021 **Posts:** 3

GIMP Version: 2.8.14
Operating System: Mac OS
GIMP Experience: New User
URL or Image link: http://https://www.picfair.com/pics/033069-white-faced-owl

Morning everyone,

First post and I'm a complete alien to GIMP and pretty useless when it comes to computers not a great start. I'm an ornithologist and researcher and came across GIMP reading a scientific paper that relates to some research I'm carrying out.

My question is does anyone here have any experience of using GIMP to measure facial features? My research is based on owls and I want to be able to measure the different features of an owls face such as feather tufts, eye size but also the difference in feather shades. Take a look at the image of a White Faced owl to give you an idea - my initial thought was to measure the pixels or squares on a grid for black feathers around the edge of the face and white feathers of the facial disc.

These are just hypotheses at the moment to explain why owls have different features and coloured feathers on their face.

If you made it this far thanks! Any views, ideas and constructive opinions welcomed!

sallyanne · **Posted:** Tue Mar 30, 2021 6:09 am **(#2)**

Can't help you out, sorry but would like to welcome you to Gimp Chat

Owlface23 · **Joined:** Mar 30, 2021 **Posts:** 3

Thanks for the welcome! :bigthup

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4756

Owlface23 wrote:

GIMP Version: 2.8.14
Operating System: Mac OS
GIMP Experience: New User
URL or Image link: http://https://www.picfair.com/pics/033069-white-faced-owl

Morning everyone,

First post and I'm a complete alien to GIMP and pretty useless when it comes to computers not a great start. I'm an ornithologist and researcher and came across GIMP reading a scientific paper that relates to some research I'm carrying out.

My question is does anyone here have any experience of using GIMP to measure facial features? My research is based on owls and I want to be able to measure the different features of an owls face such as feather tufts, eye size but also the difference in feather shades. Take a look at the image of a White Faced owl to give you an idea - my initial thought was to measure the pixels or squares on a grid for black feathers around the edge of the face and white feathers of the facial disc.

These are just hypotheses at the moment to explain why owls have different features and coloured feathers on their face.

If you made it this far thanks! Any views, ideas and constructive opinions welcomed!

In practice, unless you are photographing a dead owl, you'll likely not be exactly straight and will have perspective issues, so it depends how accurate you want to be. And unless you have a calibration scale (and perhaps a greyscale chart) in the picture it is difficult to obtain accurate measurements from a photo taken with a general camera and lens.

Owlface23 · **Joined:** Mar 30, 2021 **Posts:** 3

Thanks for the reply. So both of what you have mentioned are possible and have been achieved in previous papers including with owls. People have used front on profile images and measured from set points using ImageJ and Adobe.

I'm interested in the ability of laying over a grid and measuring the change in colouration or shade of feathering and/or the possibility of measuring pixels to quantify the areas the different features cover on the face of an owl.

Unfortunately it won't let me tag in some interesting papers as it thinks I'm a bot when I do it.

sallyanne · **Posted:** Thu Apr 01, 2021 6:29 am **(#6)**

Owlface23 wrote:

Thanks for the reply. So both of what you have mentioned are possible and have been achieved in previous papers including with owls. People have used front on profile images and measured from set points using ImageJ and Adobe.

I'm interested in the ability of laying over a grid and measuring the change in colouration or shade of feathering and/or the possibility of measuring pixels to quantify the areas the different features cover on the face of an owl.

Unfortunately it won't let me tag in some interesting papers as it thinks I'm a bot when I do it.

You just need to make a couple more posts and you will be able