Seth Killian spoke to SiliconEra about 3rd Strike Online recently. In an excerpt from the interview, Seth mentions that the graphics filters used in 3sO are applied on a per-character basis.
“There are three filters, including an unfiltered version and we can’t take any credit for that. Even when the other two filters are applied they are applied on a per character basis. The way the original characters were drawn they were shaded differently. The use of negative space and shadows varies across characters. Even if you apply a filter that looks good overall to some of the characters, it doesn’t necessarily look good to all of the characters.”