My favourite Lovecraft stories are "The Colour Out of Space" and "Rats in the Walls", but I have a hard time imagining the former as a movie - the specific idea of an unknown colour is part of the story's charm (and I feel it'd need to be padded out to film length, which is why Lovecraft's longer work is better suited).
"The Colour Out of Space" has been filmed at least twice, as Die, Monster, Die
with Boris Karloff, and The Curse
with Wil Wheaton (really). But, yeah, neither really works.