1. A computer-implemented method for image segmentation, comprising: receiving images captured by cameras in a camera array; determining optical flow fields between pairs of the images captured simultaneously by two or more cameras in the camera array; computing one or more pseudo depth maps from the optical flow fields, wherein pseudo depths in each pseudo depth map of the one or more pseudo depth maps indicate relative depths of pixels with respect to other pixels in the pseudo depth map but not actual depth measurements, and wherein at least one of the one or more pseudo depth maps is computed by performing steps including: removing from an associated one of the optical flow fields a global translational component of motion, thereby producing a residual flow field, offsetting the residual flow field by a component-wise minimum of the residual flow field, and normalizing a magnitude of the offset residual flow field to a range; and segmenting one or more of the images based, at least in part, on one or more of the computed pseudo depth maps.