I’m currently playing around with Hugo’s image resizing feature and am curious about the Permalink format that resized images get. For example if I reformat an image called image.png it gets files named like this:
image_hua93d31d2c8d7b4296307a0bede783964_216632_300x0_resize_box_3.png
The latter part of the filename makes sense to me, 300x0 means resized to 300 pixels wide and not changing the height.
What is the start of the filename? Specifically the hua93d31d2c8d7b4296307a0bede783964 and 216632 portions? Its the same across all the resized files, eg image_hua93d31d2c8d7b4296307a0bede783964_216632_1700x0_resize_box_3.png has the same random string even though its 1700 not 300.
I’m trying to find out whether its a hash of some type of the original file name I can rely on being unique so I can determine what cache-control headers I set for the resized filenames. It does change if I replace the original image.png with a different file so I’m assuming it is a hash of some type, I just can’t tell what 
Hopefully that makes sense and thanks in advance!