Cine Gamma

[Glenn Gipson]

I maybe confused about cine-gamma, so what exactly does it do?

[Chris Hurd]

The DVX100's cine-gamma setting increases the camera’s highlight and shadow latitudes by about two stops. See a detailed explanation at http://www.adamwilt.com/24p/index.html#GammaSettings.

[Glenn Gipson]

Thanks Chris.

[Ignacio Rodriguez]

There seem to be contradictory opinions about what the 'cine-like' gamma is intended for. According to many, including venerables like Adam Wilt, it yields a film like response. According to others it does not simulate film.

I think video cameras usually have a transfer function which is non-linear (some high end cams even have a programmable transfer function). And when you use 'cine-like' gamma on the DVX100 you are providing a linear gamma that will render a more faithfull tonal reproduction, so that when you transfer to film you will get the desired film-look. Linear, really. Check the graph:
http://www.adamwilt.com/24p/DVX100-gamma.gif

This is consistent with DVFilm's recommendation for shooting video with the DVX100 to be transferred to film:
http://www.dvfilm.com/maker/dvx100settings.htm

Adam Wilt, in reference to 'cine-like' gamma mode: "The caveat is that there is NO highlight compression at all: the tonal scale runs smoothly right up to 109% and then whacks right into a flat white ceiling"

Jon Fauer, ASC: "We first noticed that one of the options, 'Cine Gamma,' is something of a misnomer in the sense that it isn't a film look for video capture. This setting is used when you know that the captured images are going back to film" . This comes from:
http://www.theasc.com/magazine/product.htm

[Don Donatello]

cine gamma sounds sooooo good ..
i just love the sound of it.
but the bottom line - it SELLS

it's a add on name used to sell/market the camera ..

which would you BUY

video camera
video camera with cine gamma
24p video camera
24p video camera with cine gamma

i thing cine gamma wins everytime

[Ignacio Rodriguez]

You have a point. Nobody would buy it for 'flat gamma' :D

[Glenn Gipson]

"Film has an S-shaped gamma curve, which gradually rolls off response as the film nears full exposure. This is kinder and more forgiving for hot spots than the flat gamma curve of video." -Lighting for Digital Video and Television, John Jackman.

A Cine Gamma "like" curve in video attempts to emulate this S-Shaped gamma curve of film. So your hot spots don't abruptly appear via a "hard edge." Instead, with Cine-Gamma, your hot-spots transition through softer edges, the way film does.

And when you transfer to film there really is nothing "special" that you would have to do as opposed to when you are staying on video. You just want your image to look "film" like. Other then the fact that your image will get a little softer when going to film (so therefore you should avoid soft filters), what you see is what you get, whether staying in video or going to film. (I've seen DVX100 footage blown up to 35mm myself.) Cine-Gamma is just as useful for a straight-to-Video image as it is for a straight-to-film image, it's not something you only use when going to film. But somehow...maybe we're both right.

[Ignacio Rodriguez]

> So your hot spots don't abruptly appear
> via a "hard edge." Instead, with Cine-Gamma,
> your hot-spots transition through softer edges,
> the way film does.

Yes... that is what one would expect from a camera that attempts to achieve the look of film tranferred to video and it's also what one usually tries to do with other videocams by underexposing and then using a non-linear transfer function like Stib's Film Curves.

But, if you look at the graph posted on Adam Wilt's site, you can see that the DVX100 'cine-like' would seem give an even harder overexposure edge, not a softer one :S

Anyway, whatever the effect, I find it great that non-linear functions, proscan and alternate frame rates are being included in more and more cameras and that gives us more choices.