Script idea to cover up rolling shutter on flashes

Laurence wrote on 3/13/2008, 12:23 AM
A lot of people have noticed that flash photography really messes up CMOS based video cameras because of the rolling shutter. The flash looks sort of torn and you only see it on part of the frame.

Anyway, how about a script that overlays a single white frame, maybe with a bit of opacity, over the offending rolling shutter flash frames. The end result would be just a natural flash of white that you would expect from a camera flash instead of the half illuminated and torn frame that you get with the rolling shutter.

Comments

malowz wrote on 3/13/2008, 5:40 AM
i think it is a great idea, i was seen hdv videos on cmos cameras and the flashes looks very ugly.

but, i think theres a problem. interlaced videos may have the flash in only "half" of fields, so theres a extra care on "precision" of white over the flash.

once a time, ive uset a white color over the flashes, and ive put a 2 frames white, making the first frame at 45~50% and the next at 90~95%.



jetdv wrote on 3/13/2008, 6:58 AM
The script already exists. The "Fix Bad Frame" tool in Excalibur should do this for you just fine.
Laurence wrote on 3/13/2008, 8:42 AM
The "Fix Bad Frame" tool in Excalibur is cool but it replaces the offending frame with a previous or next frame. I don't want to get rid of the flash. I just want it to look more natural when I'm using a CMOS camera.
johnmeyer wrote on 3/13/2008, 4:37 PM
Can you post a still of the frame? That way I can tell whether it can be fixed with a script in a manner that would be better than what Ed (jetdv) suggests. In many cases, especially at weddings where there are lots of flashes but little movement, the repeated frame is hardly noticeable.
malowz wrote on 3/13/2008, 11:18 PM
this is a ugly one ;)

http://img212.imageshack.us/img212/8405/rollingre6.jpg
Laurence wrote on 3/17/2008, 12:36 PM
Maybe the best approach would be a combination of techniques: that is to repeat the frame before or after the rolling shutter flash frame, then overlay a white frame with a bit of transparency assigned to it.
johnmeyer wrote on 3/17/2008, 2:49 PM
Well, if that is what Laurence is getting, then Ed's solution is by far the best thing you can do. That is completely unrecoverable by any means I know about.

For those that didn't look, here's the picture from the link provided two posts up:



Laurence wrote on 3/27/2008, 9:03 AM
To look that bad, the flash has to be pointing in the camera. Usually that is not the case and the problem isn't that bad.
malowz wrote on 3/29/2008, 6:18 PM
the flash whas not pointed to camera, the "2 parts" is caused by the "evaluation-flash" of some cameras. it has 2 weak and fast flashes, them, the "real" flash.

ive got the video if you want, a friend shoot it.