I know in Batch Converter you can add a DSP effect (ID Tag Processing) which can reduce the size of the image embedded into the mp3.

But is there a way of reducing the image file only, without actually converting the mp3's please?

I have lots of mp3's that I want to reduce the image size only, but as they are all different bitrates, and I want to keep the same bitrates, I don't think I can use Batch Converter can I?