View Full Version : the out of focus parts look bad
Hello
I have problem with a videoclip that I shot, every time when we try to export the clip, the out of focus parts look bad, there are like circles in the colors, like topographic map.
do you know what cause this problem
Glik.
Tico Llaurador
12-12-2008, 06:00 AM
Can you show a frame of it?
Stephen Pruitt
12-12-2008, 06:17 AM
I'm certain that that's exactly normal. . . highlighted points will appear exactly as you described them. They are known as "circles of confusion." You may never have used a still camera before. If you don't like them, stop the lens down further (to increase the depth of field), use a different lens, or move further away from the subject.
Stephen
Kyle Presley
12-12-2008, 06:20 AM
Sounds like maybe color banding? What are your format and settings?
I Bloom
12-12-2008, 06:27 AM
Hello
I have problem with a videoclip that I shot, every time when we try to export the clip, the out of focus parts look bad, there are like circles in the colors, like topographic map.
do you know what cause this problem
Glik.
The format you are transcoding to is too low of a bit depth, and or the screen you are viewing on is too low of a bit depth.
IBloom
Dylan Macleod, CSC
12-12-2008, 07:13 AM
I'm certain that that's exactly normal. . . highlighted points will appear exactly as you described them. They are known as "circles of confusion." You may never have used a still camera before. If you don't like them, stop the lens down further (to increase the depth of field), use a different lens, or move further away from the subject.
Stephen
Hi Stephen
With due respect, I don't believe what he is describing is "circle of confusion".
The circle of confusion is a very difficult thing to describe. The "short" version (thanks to wikipedia) is;
"The depth of field is the region where the size of the circle of confusion is less than the resolution of the human eye (or of the display medium). Circles with a diameter less than the circle of confusion will appear to be in focus"
Although, what glik describes sounds like what "circle of confusion" should be. :-)
Ed Watkins
12-12-2008, 07:20 AM
The out of focus circles effect is called Bokeh. I doubt it is what he is referring to, the way it manifests is a function of interplay between the circle of confusion, the lens optics and the shape of the iris and it's blades.
I reckon it is more likely a banding issue due to low bit depth that he is describing, as Kyle or Ian suggest.
Here's an image showing Bokeh below:
http://upload.wikimedia.org/wikipedia/commons/8/8a/Josefina_with_Bokeh.jpg
Catalin LEESCU
12-12-2008, 07:21 AM
Banding.
Check your export settings - hint: export in uncompressed formats.
Dylan Macleod, CSC
12-12-2008, 07:25 AM
Hey Glik
Post a still...
Matthew Bennett
12-12-2008, 07:58 AM
Ah, the terrors of 8bit banding.
Remember if you're working in 8bit depth, then those 8bits can only represent 256 greyscale positions.. and you will see 'banding' or the topographic map effect you talked about...
If you export/work in 10bit or 16bit (apple prores HQ or a 16bit tiff for example), then those effects will be lessened, 'cause there are so many more greyscale positions represented by those higher bit depths.
It wasn't until I worked with such low-noise footage as the RED produces that I really started to notice that noise actually works to cover those banded areas when you're working with most video cameras... you actually need it in an 8bit world, (such as the dvx, hvx, etc..)
Esteban Sosnitsky
12-12-2008, 09:35 AM
An image is worth a thousand words..
Steve Sherrick
12-12-2008, 10:02 AM
Need to know exactly which settings were used on export, and a refernce still would be great. But I agree with the guys, it sounds like a banding issue. If you are seeing it in smooth white sections of the video that would be a giveaway. Unless you have a 10bit monitor, it's going to be hard to know what's what. If you have a monitor that does really good dithering to 8-bit display, these artifacts will be less. Keep in mind that when you preview on your Red LCD, I believe the bit depth is truncated. And I'm pretty sure they are not quite 8-bit displays either, although I could be wrong. Almost seem like they may be 6-bit, at least the original 5.6"
Jason Sinclair
12-13-2008, 01:53 AM
I suffer a circle of confusion everyday of my life.
sander kamp
12-13-2008, 02:35 AM
What are you using to export from and in what codec? I and others have experienced that exporting quicktimes (any kind) from RedCine will result in banding, especially in dark out of focus areas. Exporting quicktimes from RedRushes or Clipfinder has that a lot less but it can still be there.
Simon Valderrama
12-13-2008, 02:57 AM
I suffer a circle of confusion everyday of my life.
:biggrin: :biggrin: :biggrin:
Ramesh Jai
12-13-2008, 03:03 AM
I'm certain that that's exactly normal. . . highlighted points will appear exactly as you described them. They are known as "circles of confusion." You may never have used a still camera before. If you don't like them, stop the lens down further (to increase the depth of field), use a different lens, or move further away from the subject.
Stephen
I don't think that's the issue because the problem only occurs when 'glik' exports the clip. It has probably got to do with export settings.