0-255 image plot

Hi Everyone,
Im new to the community and FIJI.I am working on data with images.Why imageJ takes only 0-255? If I have to compare intensity of 2 images what you be the best way. I have tried to comapre two images but they have maximum 255 for each and it was difiicult to compare.Here are two images with their profiles to compare
image

Your images are 8-bit - by definition, these images can only store values up to 255. More worringly, it seems that at the very least the image on the right is saturated (i.e. there are values that would have been larger than 255 is it wasn’t for the limitation of the image type) - you can see that by the flat regions on the profiles. That means you have lost the information in these areas, since you cannot recover what the actual intensity value was. If you have control over the imaging procedure, decreasing the intensities (by, for example, decreasing the gain when acquiring them) would make for better images and it would definitely make it easier to compare them. You should aim to never ever be close to the maximum value your images can store!