Lightfields

Traditional photographs are 2D objects that capture all of the light rays passing through a single point. Lightfields are 4D objects that capture all of the light rays passing through some 2D surface, like a plane. The Stanford Light Field Archive captured their lightfields by taking many photographs of the same scene from different positions, in a 17x17 grid.

Depth Refocusing

Objects far away from the camera do not move much in the photograph when the camera moves, while objects closer to the camera move significantly. Thus, when all the images are averaged together, objects in the back are sharp and in focus while objects in the front are blurry. Furthermore, by shifting each image such that certain depths line up before we average them, we can refocus the final image.

Back Focus Center Focus Front Focus

Aperture Adjustment

Even objects near the focal depth will move drastically if the camera position changes drastically. This causes our averaged images to have a very narrow depth of field, similar to photographs taken using large apertures. By reducing the size of the grid we use, objects near the focal depth do not move as much and will remain in focus when the grid of images is averaged. This results in a larger depth of field, similar to photographs taken using small apertures.

17x17 grid 7x7 grid 3x3 grid

What I Learned

I learned what lightfields are! And how we can use them to generate a variety of different images!