Albert Barnes Commentary Ezekiel 8:12

"Then said he unto me, Son of man, hast thou seen what the elders of the house of Israel do in the dark, every man in his chambers of imagery? for they say, Jehovah seeth us not; Jehovah hath forsaken the land." — Ezekiel 8:12 (ASV)

In the dark - Hidden in the secret places which the seer dug through the wall to discover.

Chambers of his imagery - that is, chambers painted with images.