Bad Thumbnail Image Quality

Hello,
Since we changed from Cs-cart version 3x to version 4.9.3, I've noticed that the category thumbnail images are very bad quality when displayed on the product category pages. I believe this is because the new system only allows for one image size to be uploaded. If the image is larger then the system reduces the size down to a thumbnail size. Unfortunately when this happens its causes the quality to be reduced. The old 3X version allowed for a thumbnail and larger image upload which did not resize the images when displayed. Is there a way to get the image quality better, possibly allow a separate thumbnail for category pages to be uploaded?

Thank you for any assistance.

when I upgraded from 3 to 4.5 2 it was fine,

have you checked the thumbnail settings in settings>thumbnails

when I upgraded from 3 to 4.5 2 it was fine,

have you checked the thumbnail settings in settings>thumbnails

Yes I checked that also. The quality is at the highest setting (100). I believe the issue is the cs-cart system is doing a poor job of sizing the larger images down to thumbnails. This makes them blurry. In the older 3X system you could upload a separate thumbnail image that you had more control over the quality when resizing. Is there a way to upload a separate thumbnail image?