Some Kick-Ass VFX
Lindahl, who previously worked with Vaughn on Stardust, suggests this wasn't an in-your-face vfx film, even with nearly 850 shots. The idea was to be gritty and realistic and not to venture into the fantastical, so the vfx needed to be understated in keeping with the feel of the story. However, the shot count escalated throughout the shoot so Double Negative couldn't handle it all.
"The graphic novel was always referenced on the set," Lindahl says. "In terms of our work, all we had to look at was the blood effect. The graphic novel is very gory. The way we did that is instead of shooting practical blood on set, which would've been very time consuming, we shot lots of practical elements on greenscreen later on and composited all the blood. We had the benefit of having a fairly finished cut by the time we got to the effects shoot so we could figure out what angles and action we needed of the blood -- everything from bullets exiting people's heads to knives going through bodies and legs being cut off. Blood is such an important part because there is so much of it. Matthew had an idea at one point of considering a comic book feel to it as it was spurted out into the air. So we did quite a lot of testing on that as far as treating our elements like they were hand-drawn. We also did some other tests on hand-drawn blood. But it looked kind of weird to have this comic book-looking blood in a [live-action] scene so we went for a hybrid of real-looking blood but the amount of blood was enhanced more than you'd normally get.