View Full Version : Problem with green object? (pixelshift)


Prech Marton
May 6th, 2004, 02:01 PM
I'm very new in this forum, and sorry for my english..
I will buy a GL2 too.

My filming place is almost always in nature. Lakes, skies, trees, leaves...
Is there any problem with green object with the Pixelshift technologie?
(green ccd pixels is shifted half pixel vertical and horizontal)

I have hear that:
"Some of the 3-chip camcorders that use pixel-offset (and most of the one-chippers) show vertical-line stair-stepping with motion (it is similar to, but less intense than, the common horizontal-line stair-stepping seen with near-horizontal lines in motion)"

What does this mean?

Will my trees look good on TV? Or look better with camcorder that doesn't use pixelshift (eg vx2000)

http://xm2.free.fr/images/AUT_0029.JPG

Look at the blue-green shadow at the upperleft corner of the picture. Is this the pixelshift effect?

I resize the pic to 720x576, and the fake colors is already there.
(why is the picture so grainy?)

thanx!

I will purchase in just 2 weeks! :)

Robin Davies-Rollinson
May 8th, 2004, 03:38 AM
Prech,
That effect looks to me the result of shooting the thin branch against a white background. You can get this effect on edges when the background is excessively white. However, the branch just left of centre doesn't look too bad. There is a possibility that it is a lens fault effecting the left of the image. Can you reproduce this again on a test shoot with thin objects left and right of frame against white and then compare?

Robin.

Alon Levi
May 8th, 2004, 04:40 AM
Well, I have three things to point-out :

1. The picture is not a good image to test green pixel-shifting of the camera, there is a lot of red, and quite some blue, in all areas of the pictrues, even in the "green" ones.

2. For some reason, I do not fully understand, XM-2 digital photoes at 1488x1028 (xm2) are more grainy then frame-mode grabs (720x576); but not only this - the grain is quite diffrent then normal grain, it feels more like color-stairing. (like the old 32 colors GIF's of the 80's) - But again, this is only my feeling.

3. I've used my xm-2 for quite some time now, and it's - in deed - an excellent camcorder. I've come to know it's 'limits', and 'nature' - it's a great camera for the outdoors, capable of good latitue (even in contrasty situations), and the long focal length allow composition-freedom. Hence come the green problem - I've noticed that when filming large areas of green, under direct and strong sun-light (such as grass) - these areas seem more "steep" then other areas of the picture, and the highlight rendering looks reletivly bad. I've learn to compensate by some under-exposing and by turning the sharpness dial down. but for your question - Most nature scene don't have bright-green in them (pure), so you'll get by.

Frank Granovski
May 8th, 2004, 05:30 AM
Nobody has filmed with GL2 a simple TREE?Trees looked fine when I used a GL1. I have GL2 wedding footage. Some of it was shot in Queen E. Park (Vancouver). The tree leaves, bushes and green grass looked green. My DVL9500 and MX300 footage also plays back good greens. My wedding was shot with a XL1. Greens came out as well.