Flexible Depth of Field Photography: Extended Depth of Field - (f/1.4, Fixed Focus)
Project Page: http://www.cs.columbia.edu/CAVE/proje...
The range of scene depths that appear focused in an image is known as the depth of field (DOF). Conventional cameras are limited by a fundamental trade-off between DOF and signal-to-noise ratio (SNR). For a dark scene, the aperture of the lens must be opened up to maintain SNR, which causes the DOF to reduce. Also, today’s cameras have DOFs that correspond to a single slab that is perpendicular to the optical axis. In this project, we developed an imaging system that enables one to manipulate the DOF in new and powerful ways. We propose to vary the position and/or orientation of the image detector, during the integration time of a single photograph. Even when the detector motion is very small (tens of microns), a large range of scene depths (several meters) is captured both in and out of focus.
We demonstrate four applications of flexible DOF. First, extended DOF, where a large depth range is captured with a very wide aperture (low noise) but with nearly depth-independent defocus blur. Applying deconvolution to a captured image gives an image with extended DOF and yet high SNR. We also show that we can capture scenes with discontinuous DOFs. For instance, near and far objects can be imaged with sharpness while objects in between are severely blurred. We show that our camera can also capture images with tilted DOFs (Scheimpflug imaging) without tilting the image detector. Finally, we show how our camera can capture scenes with non-planar DOFs.
Video sequences comparing the depths of field obtained from our camera and from a normal camera. This was captured with a f/1.4, Fixed Focus lens