Terminal-size detection overestimates terminal's height, have to scroll

[MaxBarraclough]

If I use imcat to display an image, I find that it seems to overestimate the terminal's height, proceeding as if it has more (horizontal) lines than it really does, with the result that I can scroll up and down a few lines to view the image, but I can't see the whole image on screen at once.

An example image I used: https://wikilovesmonuments.org.uk/wp-content/uploads/2020/11/Perch_Rock_Lighthouse_in_rock_pool.jpg

I found that resizing my PuTTY window to be shorter, did not have any effect on the output of imcat. If I resized my PuTTY window to be both shorter and narrower, this had the desired effect of causing imcat to generate a smaller output (so that on restoring it to its full size, I could see the full image at once).

I'm using Ubuntu 20.10/AArch64. On the client side I'm using PuTTY 0.74. I'm not using tmux or GNU Screen or anything like that.