Legacy ImageMagick Discussions Archive

Hello,

I'm trying to process the following image in order to remove the green screen background and replacing it with any another image:
http://img576.imageshack.us/img576/747/ ... sample.jpg

I have no influence on the quality of the green screen or the capture itself.

As I'm new to Imagick I ended up trying the command example from the docs, such as
- http://www.imagemagick.org/Usage/masking/#difference
- http://www.imagemagick.org/Usage/photos/#green_screen
- http://www.imagemagick.org/Usage/photos/#chroma_key

Also the usual -fx algorithms for green screening didn't work out for me:
http://www.multipole.org/discourse-serv ... 8b7#p74744

The results are far away from a usable mask which I would need in order to make an almost perfect cut-out.
Expected result (via Photoshop): http://img818.imageshack.us/img818/3960 ... result.jpg
Example background image: http://upload.wikimedia.org/wikipedia/c ... t_time.jpg

The processing will have to be done on multiple images with a similar green screen.

Any help or hint is appreciated.

Woops - nothing to add

Can you tell us how PS does it? Not everyone has or uses PS! Is there some PS tutorial on the topic?

try this. Adjust the fuzz value as desired.

convert greenscreensample.jpg -channel r -separate +channel -fuzz 1% -fill black -opaque black -fill white +opaque black greenscreensample_mask_1.gif

Then use

convert backgroundimage foregroundimage maskimage -compose over -composite resultimage

I use the technique used shown here http://www.youtube.com/watch?v=CpJ8E4sq ... re=related.
So Photoshop uses a mask as well, which is able to reduce noise of unclean green screen in the background.

Once you have the mask, you can clean it up often times using -morphology open or close depending up white on black or black on white

see
http://www.imagemagick.org/Usage/morphology/

You can also feather the edges.

see
http://www.imagemagick.org/Usage/masking/#difference
http://www.fmwconcepts.com/imagemagick/ ... /index.php