Quote unquote from another thread but it still applies to this:
"With regards to your issue:
Yes this bug was introduced with SF v4.3, and there was a hotfix for it, that part has been fixed. However, there are still two (unrelated) image quality issue floating around, which were not fixed in Sitefinity v4.4 (also mentioned under the known issues).
One of these will only be introduced if you manually added a RadCompression line to your web.config to even further compress the your data calls, so that's probably not the case.
There has been no fix introduced for these in SF v4.4. PITS shows the progress currently as open, but that's not always a good indicator, so shortly before a new release."
The PITS issue
mentioned there is unfortunately still open with v5.0...