How to upload the image into the forum

I want to upload some images of my experiment results with format .TIF to seek help for the method of measure distance by cellprofiler. However, the system pointed out that the image is invalid. Could you tell me what I can do to upload these images. I have browsed the answer in FAQ, but I still can not be very clear about that.

Hmmm, other posts have uploaded TIF before (see herefor an example). Perhaps the extension needs to be lower-case? Alternately, you can convert the image to a PNG and upload that.