1. A method, comprising: generating an image file at a portable computing device configured to accelerate image rendering, the image file including a first bitstream, wherein the first bitstream is based on a captured image, wherein at least a portion of the first bitstream represents a plurality of blocks related to the image, and wherein the first bitstream is encoded according to a joint photographic experts group (JPEG) format; parsing the first bitstream at the portable computing device to generate a block length map after encoding the first bitstream, the block length map including a second bitstream indicating a start position in the first bitstream of each of the plurality of blocks, wherein a particular number of bits is needed to fully express the start position of each of the plurality of blocks according to the JPEG format; calculating, at the portable computing device, a fixed number of bits to represent in the block length map length of each of the plurality of blocks, wherein the fixed number of bits is less than the particular number of bits, and wherein a first byte of the block length map specifies the fixed number of bits; determining an optimal value by obtaining a value of a minimum argument when a summation of a rounded up value of the length of each of the plurality of blocks over the value of the minimum argument multiplied by a frequency of the length and the value of the minimum argument is less than a summation of a rounded up value of the length of each of the plurality of blocks over the value of one increment of the minimum argument multiplied by the frequency of the length and the value of the one increment of the minimum argument; inserting the block length map into the first bitstream in accordance with the JPEG format at the portable computing device after the first bitstream has been encoded; and rendering the captured image utilizing the block length map at the portable computing device to identify respective start positions of one or more blocks of the first bitstream.