{"id":1291,"date":"2015-08-07T03:04:39","date_gmt":"2015-08-07T07:04:39","guid":{"rendered":"http:\/\/www.dreamlandvisions.com\/photoblog\/?p=1291"},"modified":"2016-07-24T01:58:20","modified_gmt":"2016-07-24T05:58:20","slug":"an-experiment-in-synthetic-lighting","status":"publish","type":"post","link":"http:\/\/www.dreamlandvisions.com\/photoblog\/2015\/08\/07\/an-experiment-in-synthetic-lighting\/","title":{"rendered":"An experiment in synthetic lighting."},"content":{"rendered":"

While random-surfing through various comp-sci sites looking for something vaguely photography or graphics focused that would also satisfy the programmer in me, I came across a series of articles from the 90s about synthetic lighting.\u00c2\u00a0\u00c2\u00a0 The premise is that you separate out each light source in a scene, including a shot of ONLY ambient light in order to allow you to do neat things with the lighting in post.\u00c2\u00a0\u00c2\u00a0 Reconstructing lighting in a physical scene within a digital scene, alterations of light levels, colors, intensities, etc…\u00c2\u00a0 even creating ‘negative’ lights that subtract light from a scene.\u00c2\u00a0\u00c2\u00a0\u00c2\u00a0 All of this is the bread-n-butter for 3D artists, mainly because their\u00c2\u00a0 entire world is synthetic.\u00c2\u00a0\u00c2\u00a0 However, for photographers it’s a bit more complicated.<\/p>\n

After reading several papers and blog posts about it, I decided to try my hand at a simple demonstration of the technique.\u00c2\u00a0\u00c2\u00a0 What I did was take a static object and shoot three shots of it.\u00c2\u00a0\u00c2\u00a0 One ambient, one with a strobe on the left, and one with a strobe on the right.\u00c2\u00a0\u00c2\u00a0 Then, using some photoshop magic, created an interesting synthetic lighting setup that let me do somethign I could only have done with gels and a lot more fiddling with light levels.<\/p>\n

Rather than talk about, let’s get down to the fun.\u00c2\u00a0 Get your camera out, take an ambient shot and a shot with each of two lights individually lighting the same object.\u00c2\u00a0 LOCK DOWN the camera, lights and object.\u00c2\u00a0 You’ll be compositing all three shots together a couple of times during all of this.\u00c2\u00a0 Everything has to line up perfectly.<\/p>\n

<\/p>\n

Start by taking three photos as follows:<\/p>\n

Ambient Light<\/p>\n

\"Ambient<\/a>

This is an ambient light only shot.<\/p><\/div>\n

Left Flash Only<\/p>\n

\"Lit<\/a>

This image was shot with a naked speedlight to camera left.<\/p><\/div>\n

flash right only<\/p>\n

\"Lit<\/a>

This image was shot with a speedlight to camera right.<\/p><\/div>\n

Now comes the fun.\u00c2\u00a0 Load the images into Photoshop, name them something appropriate, like Bob, Sue and Alice, then group together. Call that group “Original”.\u00c2\u00a0 This will give you a copy of your original shots to go back to if you mess something up or just want to keep experimenting.<\/p>\n

Duplicate that group and call the new group ‘Subtract’
\nName the images as follows:<\/p>\n