I have not personally been particularly interested in video production and thus have not even used the video capability of my Canon 5D MKII as of yet. However, I read a very interesting article that was referenced on the Outback Photo website about the effect of anti-aliasing filters on HD video obtained via the current generation of dSLRs.
The article, entitled "Aliasing" is by Barry Green and can be found here. I found two aspects of the article quite interesting. The first was the detailed general discussion about aliasing and the artifacts it can introduce and the second was the discussion related to the fact that the type of anti-aliasing filters appropriate for high resolution digital still images and video are quite different. When both types of imaging are combined in a single camera body a compromise must be made with regards to the anti-aliasing filter (and the compromise has rightly been made to sacrifice the optimum video anti-aliasing filter in order to have the appropriate anti-aliasing for still images).
Besides being a well-written and extremely interesting article, it is also chock-full of real life video examples. It makes for some fascinating and enlightening reading.
Dec 10, 2009
Anti-Aliasing And Its Effect On HD Video
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3 comments:
Interestingly, the article is just as true of stills photography. Those horrible effects and the conclusion that a 21Mp camera is effectively only a 5Mp camera (if you want true colour and pixel accuracy) are just as valid.
This is where comparing a medium format film shot with a 21Mp digital shot seems to match up fairly well but in reality, most of the info in the 21Mp file is interpolated. If you were to shoot a subject that was just a single colour (i.e. A shot in blue shadow or a sunset with shades of red) the actual resolution of your camera has been quartered! (the same is true if you take a colour shot and convert it to black and white using a red filter - you've just thrown away all of the green and blue pixels, leaving a 5Mp shot). Green subjects fair better because there are twice as many green pixels.
How does this relate to real world shooting? Well, if you have a lot of very fine detail in your shot, the texture may look OK'ish but any fine, pixel level colour will look like it's had a two pixel blur applied..
For an example, have a look at the following
here is the actual scene as caught by a large format camera..
http://www.flickr.com/photos/timparkin/2959052951/sizes/l/
here is the Canon 5D at 100% (the original file is 200%)
http://www.flickr.com/photos/timparkin/2959052955/sizes/l/
In particular, look at the rendering of the colourful tree at the bottom right..
awesome blog, do you have twitter or facebook? i will bookmark this page thanks. jasmin holzbauer
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