Saturday, March 3, 2012

Compositing Images

Compositing can be loads of fun especially when you get the final image. Though this post is about digital compositing of images, a brief about compositing. Compositing is combining two or more images for a single image. Since video is a series of images shot one after the other, you could combine two videos together and form one interesting video. Interestingly you may have seen a composited video and not even noticed it as a composited video. If you have ever seen sports or the news when the screen splits and you see two videos playing at the same time that's a compositing.

Now back to compositing on the still side. Back in the film days this was harder to do. You would need to rewind the film to the exactly same spot where the previous exposure was and re-expose the film. What you needed to be mindful was of not only getting the composition right, one shadow does not overlap the other but also make sure that the film does not get overexposed or the entire effort would be a waste. A variation of this is double exposure but more about that some other time.

Now that the history lesson is over, lets get down to how to pull this off. Here is one I recently made. I'll walk you though how I pulled it off. What you will need is - A camera (duh.) a tripod and remote trigger (wired or a wireless trigger both will do). You can pull it off without a remote trigger but you risk moving the camera when you push the shutter button and making your life more difficult in post processing.


Once you have this set the camera on a tripod. If the scene is big then make sure you have sufficient depth of field so nothing falls out of focus when the subject moves in the scene (unless you intend to do it). You will need to move the camera to full manual. Lock the focus and the aperture. When you are locking your aperture, make sure, if you have a subject moving around the composition, then the subject is well exposed across the scene. Last but not least set a white balance even if you are shooting in raw. It will help in post processing. If you leave the settings on auto white balance then every time the person moves in the composition the camera will recalculate the white balance and would get variable colour tones. (One way to fix that would be move it to black and white but that's the last resort)

If you got that the you are done then you are done with the hard part. Now just click a series of images and take it into a software that helps you operate in layers. (Gimp/Photoshop.) Put the various photos one on top of the other and just paint in the part you want in the composition. 

A word of caution. If you are using flash in your images then using a light meter would help. You would also need to be more careful of where all the light is falling. If a subject stands before a flash then the light gets blocked by the subject and the illumination of scene would vary adding to the degree of difficulty of the image.

If all of this is too confusing below is a are a few video tutorial to help you better understand how this works.