Zulf,
I have deleted and re-uploaded the images several times, and the problem persists. I created it in two places:
1. On the slider:
Customize > Featured Slider Options > Set Slider max-height (numbers only!) – Default is 500! > set to 400.
On the slider, even being set to 500 creates a distortion, but it’s also too big for the front page (hence my setting to 400).
2. On individual posts:
Customize > TwentyFourteen General Options > Set Overall Content Image max-height (numbers only!) – maximum recommended is 572. > set to 400
On the individual pages, set to 572 is still distorted, and is also too big for the individual page (can’t see any text below the image without scrolling.
BUT, thumbnails in the grid below the slider are not distorted in any way–they are cropping themselves just fine–, it’s just the headers which are getting distorted.
Thanks!
Valerie