Infinity values and Area fraction

Hi guys,

I am relatively new to ImageJ and image analysis in general. After lots of reading on forums I managed to split and binarize two channels of a fluorescent microscopy image. My goal was to see whether the pixels from these two channels have similar spatial distribution. So I decided to use the image calculator and divine channel 1/channel 2 and then channel 2/channel 1. The results were showing as 32 bit float images. My hypothesis was that if both channels have similar pixel distribution I should be able to see that the area occupied by pixels with value of is comparable in both cases. So in order to do that I checked the area fraction box in the set measurements window, which according to imageJ manual should give me the % of area that pixels with values other than zero occupy. My question to you is the following. I know that NaNs are not calculated in the area fraction but what about the infinity values? Are these part of the final area fraction?

Hi there,
I think here is a similar post which may be of help to you - How to divide two images using Image Calculator?

Thank you @Praveen. I had found this post before but unfortunately I was not able to answer my question.

Hi @sozerv, if you want to see overlapping regions, why don’t you multiply instead of dividing?


Thank you for your response @pmascalchi. I can see how I can calculate overlapping regions with dividing or adding the two pictures but I haven’t thought about multiplying. Maybe that would be an interesting approach. Nevertheless, my question is not on how to generally show that two channels are overlapping and it is much more specific. I want to know whether the infinity values that you are getting in a 32 bit float image are included in the calculation of the %area in the results window.

Hi @sozerv,
Sorry but I don’t understand why you didn’t answer this question by testing it in IJ?
I didn’t know the answer, but testing it with a dummy image I created shows that infinite values are not taken in account…

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