1. A method of converting data in a file using an apparatus having a processor and a memory, the method comprising: checking for a first data portion of a plurality of data portions in the file, the first data portion being a critical data chunk in a Portable Network Graphics (PNG) file and having a first data value; reading in data from a second data portion of the plurality of data portions; decoding the data in the second data portion of the plurality of data portions; wherein decoding the data in the second data portion comprises decoding data for an opaque image encoded with a four-channel blue, green, red and alpha format; skipping a multiplication of a color value with a transparency value if the first data portion having the first data value is detected; performing a checksum operation using the processor on the decoded data from the second data portion if the first data portion having the first data value is not detected; and skipping the checksum operation on the decoded data from the second data portion if the first data portion having a first data value is detected.