Why can the image be distorted during resizing?

Question

Yii

Site on yii2. There is a standard Imagine resizer.
Lately there are pictures that are distorted during resizing:

or here:

You see the edges are clumsy. The original is normal, but the miniature is kotsana. At what some norms, and 30% kotsannye. I don't even know where to look for the bug. Who faced this? Could this be the result of server load?

Answer 1

Show the code first. most likely you have a mismatch between width and height.
And which Imagine are you using.