API change/update

Currently, the API provides a way to give the location of the input file for processing and requires the desired location of the output. This inhibits the flexibility of the library to some extent.

Another way would require the API to deal directly with the image matrices rather than the location and the onus of I/O would fall on the developer. However, completely eliminating the current API would pose a problem to people who are looking for plug-n-play solution. Thus, it might be better to support both the forms of API.

Any suggestions are welcome. Thanks!