Cutting out objects/Recognizing borders automatically


I am not very experienced in ImageJ, but i need to measure the area % of red fibres in tissue. I can make it work by splitting the channels cutting out the object and setting a treshold and then simply measure it.
Unfortunatly i have a huge (really HUGE) amount of photos to quantify, so i started to read about makros. My Problem is that i can not manage Image J to “recognize” my sample boarders by itself, so that i still have to cut out everything by hand.
Unfortunatly i can not upload a picture of this, but try to imagine it as a slice of Cheese. I want the Program to find the borders itself, so that it measures the Yellow Area % of the Cheeseslice compared to the whole Area of the Cheeseslice.
This picture is actually quite close to my material:

Short: I want the Program to cut out the slice automatically and measure the amount of cheese in the slice.

Please excuse my non-technical-language, i just recently started to work with ImageJ.

I would be very thankful if someone could help me.


On YouTube you will find several tutorials which will help you:


First i want to apologize for thelong time it took me to answer!

@Bio7: Thank you very much, i will try this as soon as possible (right now i do not have access to my picture-data)

I will tell if it worked out!

Thanks a lot!

Greetings MiniRick

You can also use another approach to seperate the background from the cheese.See this post and example which extracts a very similar structure: