I am a student who has been working on a year-long group project. My classmates and I are testing 4 different Cedar tree stock-types natural resistance to deer browse. We took initial photographs of the seedlings against a black and white grid. We will go out into the field at a later date and take new photographs. What i want to do with imageJ is take each image and measure the coloured pixels (the tree) vs the total number of pixels. By doing this we could calculate the foiliar surface coverage of the seedling before and after being planted to calculate the net change in surface area. I will attach a picture so you can see more clearly what i am talking about.I think i will have to crop the photo so only the white grid and tree are present (remove any background). Any advice is greatly appreciated.