images on homepage page a little blurry under product images and featured images

Hi ,the images on the homepage under “product categories” and “featured products” are not so clear{a little blurry} . They seem to need more sharpening.
I have installed the regenerate thumbnails plugin and then went setting> catalogue >image options.I Set thumbnails at Width 550 x height 550. then went to media to regenerate thumbnails but it did not sharpen up the images.
could some one please help! Thanks