This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
This filter simulates blood stains and splattering. You can use it with an imported image or without.
The 'Opaque - Transparent' control allows for the effect to be overlayed on another image or by itself with a transparent background.
You might also find this filter useful as a paint filter.
I've also added Crapadilla's suggested changes to this version. Thanks, Dilla. I also renamed 'Blood Stretch' to 'Blood Thinner'. And, I modified the texture leg to take advantage of Dilla's suggestions as well.
Craig Kraellin Walters blood stain transparent opaque image paint smooth Crapadilla dark depth highlights pooled dried stain splatter
This filter has earned its author one of our rewards. They are given to the authors of popular filters and include a free copy of Filter Forge.