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-   -   XM2 - Glow around subject :( (https://www.dvinfo.net/forum/canon-gl-series-dv-camcorders/75053-xm2-glow-around-subject.html)

Luke Sparke September 8th, 2006 03:27 AM

XM2 - Glow around subject :(
 
Hey guys, long time reader, 1st time poster. Sorry had to get that out of the way.

http://www.mrflibble.net/sitebuilder.../blue_glow.jpg

I was filming for a promo video and notice that the subjects have a glow around them, like a colour bleed. Settings were:

50 FPS
3.4 F
0 Gain

1000 watt key and 500 watt fill.

You can see it's really bad, especially on the arms around the end of the t-shirt on the left hand side.

I'd previously tried some green screening which failed terribly. I thought it was because the background was too bright and was spilling light onto the subject, but this makes me think the subject was actually spilling. Anyway, anyone know what i can do about it? Is it a camera fault?

Don Palomaki September 8th, 2006 04:29 AM

Does reducing camera color saturation help?

Luke Sparke September 8th, 2006 07:42 AM

Hadn't thought of that, i'll give it a try and let you know, cheers.

Nathaniel McInnes September 8th, 2006 02:24 PM

let me get this, you re keying. if you are i have good knowledge in this subject. If you are, try this. if you are on a package like arfter effects or final cut do this. add mulitlple keying layers. not one. to a spread between say 20 color diffence. not a big chunk of green in the color chart. also try and bring the smothness up much more. because you were using an xm2 you will sadly get this. if you are really determined and you are going to do alot of keying you should get a hdv camcorder

Luke Sparke September 8th, 2006 09:17 PM

Actually, i don't plan to do a heap of keying, but i do want to do some, the biggest problem i have at the moment is just bad footage, keying or not.

Don, i reduced the colour saturation all the way, made no difference. However, i reduced the sharpness all the way and it got rid of the problem. FYI moving the colour phase all the way to green and all the way to red made no difference, and the setup level all the way down, no difference.

Here's some things i noticed. I had a blue cushion on a grey chair in front of a white background. In the view finder and on the LCD the cushion had a blue glow, but once i transfered to the PC, the glow was gone. However, the grey chair had a white glow along it. So in the footage i go on and on about the blue glow on the cushion, but actually it was the chair that had the glow. My point in all this is that the cushion was in focus, but the chair, only slightly behind it, but because of the shallow DOF was slightly out of focus. So perhaps it's the fact that an object slightly out of focus gets a glow, and reducing the overall sharpness fixes the problem.

Now i don't mind having sharpness all the way down, gives everything a nice soft look, but is there something else i can do? Once i've edited and compressed, i'll post the footage i shot today, you can see what i'm talking about.

Nathaniel McInnes September 9th, 2006 03:19 AM

ive done alot of croma in the worst situations. i have even done croma in direct sunlight. what editing package are you using. also what are you tring to film

Don Palomaki September 9th, 2006 05:57 AM

I'm no expert, but the best place to judge the image is on a full resolution monitor. The EVF and LCD panel on the camcorder are low resolution and probably loose a lot as well as introduce new artifacts when the 720x480 image is mapped to their limited pixel count.

Image processing, such as sharpness enhancment (and compression for that matter), can introduce artifacts especially near high contrast/sharp boundaries/edges in the image. The glow or ghost is one form. The work around appears to be to tweak with camcorder settings (and the set and lighting if you can) to minimize the unwanted effects.

Luke Sparke September 13th, 2006 07:02 AM

http://www.mrflibble.net/sitebuilder...1/4/7/glow.wmv

Finally put something together to show what i'm talking about.

Nathaniel, i use Premiere Pro 1.5. I've got a demo of after effects but can't really afford that at the moment, plus it didn't do much better than Premiere.

http://www.mrflibble.net/sitebuilder...een_screen.avi

Here's a 32 frame clip (PAL) of some keyable footage in DV format. The gain was up at about 6db i think, which is bad, i didn't have enough light. I'm interested in your 20 layer thing. How do you do that? Have you got a step-by-step guide somewhere, either on this forum or on another webpage? This footage has the same glow issue, so if your 20 layer thing gets around it, i'll be really happy.


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