Chroma Key (ignorance on my part?)

jerrys

Senior Contributor Location: New Britain, CT, USA (between New York and Boston) Joined: Feb 10, 2010 21:36 Messages: 1038 Offline

Solved by

Jul 12, 2012 20:00

I'm trying to use chroma key for the first time. I'm attaching sample PNG files to illustrate what's happening. All I want to do is make the white (background) transparent.

When I apply a chroma key, using white as my "green screen" color, the background becomes transparent; the interiors of the black squiggles stay black; but there is a white border around my squiggles.

There's no anti-aliasing involved (that's a different nightmare).

When I replace the white with red in my photo editor, there are no white borders.

Am I missing something, or is the chroma key function off by one pixel? Perhaps it's doing some kind of lossy compression on the image?

==> I forgot to mention that if I don't put a color board behind my PIP object, the white border still appears on the black (empty) background.


Filename	Image2.png	Download
Description	Using chroma key in PD, red color board as background
Filesize	36 Kbytes
Downloaded:	197 time(s)


Filename	Image3.png	Download
Description	White replaced with red in photo editor
Filesize	5 Kbytes
Downloaded:	182 time(s)


Filename	Image1.png	Download
Description	Original file - white background, black foreground
Filesize	5 Kbytes
Downloaded:	206 time(s)

This message was edited 1 time. Last update was at Jul 12. 2012 20:03

Jerry Schwartz

Carl312

Senior Contributor Location: Texas, USA Joined: Mar 16, 2010 20:11 Messages: 9090 Offline

Jul 12, 2012 20:31

I think the white border is a function of chroma Key in Powerdirector.

You can do a much better remove of the white background in a photo editor.

Even when you adjust the intensity in chroma key, you still have the white borders around the black objects.

A different color to chroma key may give different results. The normal colors used are Green or Blue.

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BarryTheCrab

Senior Contributor Location: USA Joined: Nov 06, 2008 22:18 Messages: 6240 Offline

Jul 12, 2012 22:17

Jerry,
your images need to be more robust. Your original squiggles file is only 4.7 kb.

This message was edited 1 time. Last update was at Jul 12. 2012 22:18

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Xerox

Contributor Location: California, USA Joined: Aug 09, 2009 01:36 Messages: 446 Offline

Jul 13, 2012 07:01

In addition to chromakeying, a combination of some other effects can get rid of the white borders. Here are my settings:

Chromakey (Modify PiP): White, Intensity: 65
"Gamma Correction" (from Effects Room): 30
"Apply Re-focus" (fix/enhance): 3 Gateway DX4380, AMD A8-5500 Quad Core 3.2GHz with ATI Radeon HD 7560D; 16GB RAM; 1 TB SATA 7200 RPM; Windows 8 Pro 64-bit; PDR11, PDVD12.

jerrys

Senior Contributor Location: New Britain, CT, USA (between New York and Boston) Joined: Feb 10, 2010 21:36 Messages: 1038 Offline

Jul 13, 2012 12:35

Thanks for the suggestions, I'll give them a whirl.

Carl, PD doesn't preserve transparency when it imports an image. Jerry Schwartz

Cranston

Senior Contributor Location: USA Joined: Aug 17, 2007 02:26 Messages: 1667 Offline

Jul 13, 2012 12:54

Quote: PD doesn't preserve transparency when it imports an image.

Hmm.
But that's what all those 300,000+ PIP Objects and Particles, available for download on Cyberlink's DirectorZone are.
All are .png images, some with motion applied, on transparent backgrounds.

I must be mis-understanding what your intent/meaning/definition of "Preserve" is here.

This message was edited 1 time. Last update was at Jul 13. 2012 12:54

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jerrys

Senior Contributor Location: New Britain, CT, USA (between New York and Boston) Joined: Feb 10, 2010 21:36 Messages: 1038 Offline

Jul 13, 2012 13:26

Quote:

Quote: PD doesn't preserve transparency when it imports an image.

Hmm.
But that's what all those 300,000+ PIP Objects and Particles, available for download on Cyberlink's DirectorZone are.
All are .png images, some with motion applied, on transparent backgrounds.

I must be mis-understanding what your intent/meaning/definition of "Preserve" is here.

[Edits underlined]

Excellent point.

I just tried that again, and you are correct. PD preserves transparency with GIFs and either palette-based PNGs that have 256 colors or less, or PNGs with alpha channel based transparency; it doesn't for TIFFs. I don't know about GIFs with more than 256 colors, but I've never seen them used.

I thoroughly confused myself by using black as my foreground color.

Unfortunately, this doesn't solve the chroma key issue for them new-fangled movin' pitchers. I suppose the border isn't that obvious.

Come to think of it, if you look closely at an HD broadcast you can sometimes see a halo around the weatherman.

This message was edited 1 time. Last update was at Jul 13. 2012 13:45

Jerry Schwartz

James1

Senior Contributor Location: Surrey, B.C., Canada Joined: Jun 10, 2010 16:20 Messages: 1783 Offline

Jul 13, 2012 13:54

Hi,
Just a thought on the transparency have you adjusted the 'tolerance' slider, some (depending on programs) png files when exported as png have a small anti alias border applied to the image. This would account for the anomaly.
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jerrys

Senior Contributor Location: New Britain, CT, USA (between New York and Boston) Joined: Feb 10, 2010 21:36 Messages: 1038 Offline

Jul 13, 2012 14:31

Quote: Hi,
Just a thought on the transparency have you adjusted the 'tolerance' slider, some (depending on programs) png files when exported as png have a small anti alias border applied to the image. This would account for the anomaly.
Jim

No, there's no anti-aliasing done here.

This PNG business is somewhat beside the point. I was using PNGs as a test. What I was originally trying to do was get rid of the background of an animation (externally produced).

I described what I am trying to do in a different thread: http://forum.cyberlink.com/forum/posts/list/23966.page Jerry Schwartz