1. A method for generating depth maps, the method comprising: receiving, by one or more computing devices, a set of image frames, each image frame of the set of image frames including pixels; aligning, by the one or more computing devices, the set of image frames to provide flows of the pixels in the set of image frames; identifying, by the one or more computing devices, any region of bokeh effect in each image frame of the set of image frames by measuring sizes of areas of expansion across image frames of the set of image frames using an assumption that contour expansion due to a bokeh effect has consistent movements through frames of the set of frames and the flows; adjusting, by the one or more computing devices, the alignment of the set of image frames based at least in part on the identified regions of bokeh effect; generating, by the one or more computing devices, for each particular image frame of the set of image frames an index map of focus values for the pixels of that particular image frame using the improved alignment; and generating, by the one or more computing devices, a depth map based at least in part on the index maps.