The image in the article is also not really low-res. As far as I can see Stereo’s CCDs have a resolution of 2048x2048, the image in the press release is 1280x720, that’s not exactly a substantial reduction (also considering that the two images from the two spacecraft were heavily distorted to create this side-view of the sun).
By the way, I found this wiki about processing and analyzing SECCHI’s images, if you wanted to you could presumably learn about it and start processing images on your own: http://secchi.nrl.navy.mil/wiki/pmwiki.php?n=Main.DataProces...