Dear contest holder
Don't worry, after you select a winner on your contest, you can ask other format file you wanted as written on legal contract :
"The designer/vendor agrees to provide the buyer with a vector file in .EPS format as well as a .JPG of the winning logo. The designer/vendor also agrees to provide additional variations upon request including: White Background, Colored Background, Black & White, and Solid Colors. Additional requested formats can include .AI and .PNG. All deliverables are referenced herein as defined as the ("Logo"). Variation requests are required to take place within 2 weeks of selecting a winner."
tiff format are included too. Thank you
nzr