hi,

see you upload your picture and it was accepted for jee main exam, so it concludes that picture was in right format, thats why your application gets accepted and you are able to download your admit card. so just right now focus on your exam, and there will be no problem in the exam hall..make sure to bring the necessary things 2 copies of passport size photo, 1 authorized ID proof along with jee main admit card in the exam hall. read the instructions carefully which mention in the admit card.