Open the image in photoshop, go to image size make sure contrain proportions is selected and change the width to 149 px this will automatically change to height to approx 86 (don't change this because it will also then change the height) selecting constrain proportions makes it so you don't squash the picture, save this image re-upload and that should fix the problem.
Good Luck and feel free to ask if you need any help
