Dracut police have arrested a Lowell man they say tried to use his cellphone to take nude photos of a woman changing in an adjacent stall at a gym. Mark Renaud was granted $1,000 bail after pleading not guilty Wednesday in Lowell District Court to photographing an unsuspecting person in the nude. Prosecutors said the woman had just finished tanning at Planet Fitness in February when she went to a changing stall to dress. She told police she saw a cellphone on the floor, with the camera side up, slowly being pulled back. Renaud said he was in the adjacent stall but said he dropped the phone and merely picked it up.