Ahhh if you wanted severity scaling (and don’t add new images) it may have been better to tap into the color and opacity of the image and have it bound to a variable. Your way works perfectly fine as well though.
As for when the player is healed, do the same check in the same way. If you want, you can clean this up a bit and separate it into it’s own function, just call it “UpdateDamageUI” and have it check where the health is like you have now, but just use that function at the end of heals and damages. This consolidates how your UI updates so if there’s ever an issue you know to check the function or where it calls from easily.
Edit: Another option could be to tap into the one image widget and just change the image if it’s got to change and you don’t want it additive.