BCC Deinterlace Tutorial

By: John Lafauce

SCENARIO

You are in a bind. You have telecined video that was originally aired on TV as a documentary, and now your boss wants to show it off at the NAB booth. No problem. Just hook up an NTSC monitor and you’re set. But, the boss wants it shown on an HDTV Flat-Panel LCD TV to really wow the masses. To test the HDTV monitor, you preview the media on it and what do you see?

The dreaded "jaggies"..

Above: Combined fields of interlaced media reveal "the jaggies" in areas of motion (viewed at 400%)

The problem with interlaced images shown on a non-NTSC display is there can be errors when the two fields are synthesized into one frame. These errors are usually referred to as "the jaggies", “combing” or “teeth”, and are apparent in the moving parts of the image. What causes these comb-like artifacts around the edge of moving elements? Basically, they are the result of clashing technologies: older TV (Interlaced) vs. newer TV (Progressive).

For an in-depth explanation of this, please refer to this informative link:
www.doom9.org/index.html?/video-basics.htm

Getting Rid of the Combing (“The Jaggies”) Through Deinterlacing

You have at your disposal:

• Adobe After Effects - A host application that does deinterlacing
• BCC Deinterlace - A Boris FX plug-in that also does deinterlacing
• BCC Deinterlace - also plugs into NLEs from Avid, Apple Final Cut and Adobe Premiere.

Which do you use? Let?s do an end result comparison.

First, we’ll show you the original, interlaced image (below):

Above: Original interlaced image

Now magnified 800% to show you detail (below):

Above: Original interlaced fields

Next, is the same image deinterlaced using Adobe After Effects’ Interpret Footage feature (below):

Above: Deinterlacing in After Effects

Compared to the image deinterlaced with Boris FX's BCC Deinterlace filter (below):

Above: Deinterlacing with BCC Deinterlace

When comparing the two images, the one deinterlaced using the BCC Deinterlace filter produces a better quality edge than the job After Effects did.

If you look closely at the boy’s wrist against the tree in the background, you can see the AE version is chunkier and aliased compared to the BCC version (shown below):

Above: First image Deinterlaced with BCC, second image Deinterlaced with AE

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