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-   -   XL2 Gamma curve test stills (https://www.dvinfo.net/forum/canon-xl-gl-series-dv-camcorders/31692-xl2-gamma-curve-test-stills.html)

Barry Goyette September 10th, 2004 10:50 AM

XL2 Gamma curve test stills
 
I've posted a series of still to show the gamma curve adjustments available on the xl2. There are definitely many more options that could be shown, so I decided to stick with showing the Normal Gamma and Cinegamma in combination with three sets of knee and black adjustments

1. normal

2. Knee high, Black Press: Increased contrast through mid range, compressed highlights and shadows

3. Knee low, Black stretch: Lowered contrast through mid range, expanded highlights and shadows.

This first scene is a high contrast one with highlight and shadow detail both teetering on the edge...note the specular highlights on the dolls and bowl, and the silhouette separating the dolls head from the background.

I'll try to post a normal contrast scene, and a high key scene later.

http://homepage.mac.com/barrygoyette/PhotoAlbum19.html

Barry

Barry Goyette September 10th, 2004 11:57 AM

Second set of images posted
 
I've posted a new set of images showing the same set of curves applied to the same scene with a more "normal" contrast range. (Hi Key still to come).

Barry


http://homepage.mac.com/barrygoyette/PhotoAlbum20.html

Aaron Shaw September 10th, 2004 12:49 PM

Thanks Barry. It's hard to decide which look I enjoy most. Is it just me or does the cinegamma merely darken the entire image?

Hugh DiMauro September 10th, 2004 12:53 PM

Yes! I thougth I was going crazy! The cine gamma ADDS contrast! Is that supposed to happen? I thought cine was designed to increase the contrast range!

David Lach September 10th, 2004 01:44 PM

Nice test Barry, thanks.

Seems that Cine Gamma with a low knee and black stretch gives the best balance of all 6 images (IMO). The blacks are handled perfectly while the highlights are still soft and natural looking.

With Normal Gamma there's a tad of highlight clipping going on.

And the knee set to high/blacks set to press with Cine Gamma gives the image a weird but cool "Marlon Brando in the final sequence of Apocalypse Now" kind of look, with the subject fadding very quickly into complete darkness. Nice for some specific effects, but probably not usable in most situations I would think.

Barry Goyette September 10th, 2004 07:24 PM

Here is the final set of test images...this time the gamma curves have been applied to a high key...or brighter lighting scheme.

http://homepage.mac.com/barrygoyette/PhotoAlbum21.html

Barry

Antoine Fabi September 10th, 2004 09:29 PM

thanks Barry for these grabs.

When i saw the first XL2 grabs on the internet, i tought that it definitely did not have the color richness of my DVX100A. It seems now that all i saw was shot in normal mode.

As a happy DVX100A/anamorphic adapter user, i can tell you that i would also be happy with the XL2...no doubt now.

It seems to have an exellent color reproduction, dynamic range and image "finesse".

aaahhhh... just suppose i"ll maybe now have to own 2 cameras...

Chris Sorensen September 10th, 2004 09:53 PM

Okay, the dolls are freakin' me out. (kidding, kinda.)

Brad Carrier September 11th, 2004 06:31 AM

Chris, I hear ya. Ever since Poltergeist I can't handle dolls, clowns, or clown-dolls.

Greg Boston September 11th, 2004 08:55 AM

Yes Chris, I was thinking the same thing about those dolls. I almost posted the same message you did. I'm glad you went first!

-gb-

Barry Goyette September 11th, 2004 09:24 AM

Yeah, they bug the crap out of my girlfriend too...I guess I got used to them back in art school...a lot the girls in the program shot really creepy photos of antique dolls on a regular basis...I shot them because it was a way of approximating a skintone in a scene that I could shoot over a few days.

A few thoughts on comments about particular settings...I think that the importance of these tests is to see the range of adjustments in the camera. I'm pleased, and a bit surprised at the smoothness of the xl2's adjustments...for any doubters about the 12bit dsp in this camera...I think the adjustments look as good if not better than similar tests I've seen on the DVX100...( I haven't tested it myself...probably should..probably won't).

On the cinegamma...it does have the effect of darkening the highlight range of the image...because it is essentially taking the "knee" out of the gamma curve...normal gamma tries to compress the highlight range so that clipping doesn't happen in an "on/off" fashion. (david mentions seeing clipping in the Normal stuff...not really, as there is tone there...we're really seeing compression of the highlight, which is what the "knee" is for.)

Cinegamma assumes that you have total control over your lighting, and thus can control where that highlight hits. A classic example of when not to use cinegamma is a backlit sky like a sunset...or a gradated white wall. Normal gamma will compress that highlight producing a brighter...less saturated gradation that is relatively smooth...cinegamma will produce a richer more saturated gradation that will abruptly clip at some point producing a posterized effect. (Adam Wilt has a detailed discussion of this on his site).

Anyway, I hope these are of some use....I've gotta get back to some real work, so this will be the last of my tests for awhile.

Barry

Dejitaru Tenshi September 11th, 2004 11:06 AM

Reminds me of that horror story we all use to tell int eh dark about the doll that the girl buys that comes down the stairs, kills her dog all her familay then her. I hope you have more luck with your dolls barry, but remeber if they do start to display any agressivness in the way they stay perfectly still, then threaten the good old pare of scissors. Scissors beat fabric bioch, slice slice slice.

My appologies, was my first day workin at the hair solon, got a thing bout scisors.


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