1. A method comprising: capturing a first image illuminated by natural light; capturing a second image illuminated by infrared light, wherein the second image is captured at the same time as the first image; determining R, G, and B values for each pixel in the first image; calculating an intensity for each pixel in the first image; calculating an IR intensity for each pixel in the second image; estimating a depth value for each pixel using the ratio of the IR intensity and the intensity of corresponding pixels in the first and second images; and storing the estimated depth value for each pixel in an image depth map.