Late 60' horror when something gory was about to happen a red flash would cover the screen whats the name?

Question

mid 60' to early 70' could be a hammer film please help me out thank you jack the ripper,dr jekyll mr hyde type of movie

Answer 1

Chamber of Horrors (1966)

IMDb review:

Borrowing a page from the playbook of producers like William Castle, Al Adamson, Nicholson and Arkoff at AIP and the like, this was a lot of fun for me as a kid with the hokey gimmicks of the "Fear Flasher" and the "Horror Horn" added to prevent the more squeamish members of the audience from dying of sheer fright, (the goosebump-inducing voice of the Narrator in the "Instructional" sequence was none other than William Conrad, who actually directed one of these horror potboilers for Warner's, the Dean Jones/Connie Stevens starrer "Two on a Guillotine".)

This rehash of the definitely superior "House of Wax" with Vincent Price, gives us the grisly tale of serial strangler Jason Cravette (Patrick O'Neal in a bravura performance), who is finally caught literally red-handed as he ritualistically weds and beds his latest victim, ex mortis.

His subsequent escape and its gory consequences (he goes from being caught red-handed to losing one of them), becomes the fodder for a sensational museum of mass murderers run by suave local entrepreneur Anthony Draco (Cesare Danova, one of Warner's second-tier matinee idols). Once worried about operating in the red, soon Draco and his associates, the marvelous Wilfrid Hyde-White and diminuitive sidekick Tun-Tun (José René Ruiz~the Verne Troyer of his day) are back in business, as the slippery Cravette gives our heroes and the local authorities more red than they know what to do with, cutting a vengeful swath through the ranks of all those responsible for his near-incarceration.

TRIVIA:

This was a pilot for a period detective program from Warner Bros. entitled "House of Wax", padded out with various gimmicks including the red "fear flash" and "horror horn", several added sequences and guest stars with a larger screen in mind because it was considered too intense at that time for television.

I love this film and have a copy of it among my many videotapes! It's been awhile since I've watched it, but the red flash brought it to mind immediately. They cheat, though, and don't warn you of the one tiem you might want to cover your eyes! Now, it all seems quite mild, but it's very enjoyable.