1. A system for rendering an image using a light field image file, the system comprising: a processor; and memory containing a rendering application and a light field image file; wherein the light field image file comprises: an encoded image; and metadata describing the encoded image stored within an application marker segment within the light field image file; wherein the metadata comprises: a depth map that specifies depths for pixels in the encoded image; and a confidence map for the depth map, where the confidence map indicates the reliability of the depth values provided for pixels by the depth map; and wherein the rendering application directs the processor to render an image by applying post processing to the encoded image using metadata contained within the light field image by: locating the encoded image within the light field image file by locating a start of image marker within the light field image file; decoding the encoded image; locating the metadata within the light field image file; and processing the decoded image by modifying the pixels of the decoded image based on the depths of the pixels indicated within the depth map and the reliability of the depth values indicated within the confidence map to create a rendered image by applying a depth based effect to the pixels of the decoded image.