Photography buddies Mark & Kevin had a laugh and did a fun Waynes World” tribute set in front of a green screen. It’s a technique used a lot in the film industry to put actors in front of a make believe backdrop, these days often computer generated and motion tracked to the real world camera allowing the actor to move around a virtual world in a very convincing way. The background removal technique is called Chroma Key Compositing or Chroma Keying and uses a constant green or blue backdrop that can be subtracted easily from the filmed images easily using either analogue or more modern digital techniques. You’ve have seen it a lot, possibly without realising it – weather reporters stand in front of such a screen and motion to something that’s not really there, often looking to a monitor at the side to check they’re on target and that their team aren’t pulling a fast one of them by swapping the weather map out for something more interesting. These days there are “3D” cameras like the ZCam by 3DV Systems that are able to take 2D image and Z-depth data and in real time exclude anything beyond a desired distance or break it into layers so that a second actor can walk between the first and their backdrop as if they were there! This technology is coming into gaming now, so high end photography ones may be affordable to the resat of us very soon!

While doing my 100Strangers project I shot a couple of ladies in front of a shop that was undergoing a facelift. The builders had kindly painted it in a fairly consistent green.

With M&K’s image in mind I found my image and loaded it into GIMP. The package has a handy “Select by colour” feature. After adding an alpha channel to allow some transparency in the layer I clicked the select tool, adjusted the tolerance up to 15 and picked some green. Hitting the delete key resulted in some nice holes in the image. A few more select & delete operations and I had them both standing in front of nothing. A shot of the sea from my wife’s recent fam trip to Antigua added as a layer below and they were now somewhere much more pleasant! The select wasn’t 100 perfect around hair, resulting in some odd looking gaps. These were fixed by introducing a third layer in between background and foreground, then painting in some darks colours where I didn’t want the sea to show through. The bright light of the original shot was good for the test edit. In the studio lighting would be more controlled for the final image.