ImageResize - a simple image resizer program with multithreaded capabilities

Features:

• The program actually serves as a study to the task-based parallel programming. It simply resizes (magnifies) images without any interpolation.
• As the image loading and saving doesn't count to the real parallel processing (and it is not parallelizable and threfore has a negative effect on the performance measurments, see Amdahl's law), the program measures the time needed only for the image processing (in [msec]) and writes it after the file names.
• The parallelization of the algorithm is relatively easy: the generation of each destination line can be independently calculated and this implies a straightforward structure where the independent tasks (each processing one line) can be parallely executed. This is very similar to the ImageMagick parallel execution.
• This mode of the task dispatcher is the most widely used, in cases where there is a program section that can split up the job into independent tasks.
• The application is a good demonstration for that the SDPP and TTaskdispatcher libraries are easy to be used statically in applications.

Usage:

MTImageResize {infilename} -m {magn} -l {lines} -j {threads} {outfilename}

• magn: magnification
• lines: the number of lines in one task
• threads: the number of the execution threads

Performance results with the testimage, with different threads (more about the test here):

Threads	magn: 2	magn: 5	magn: 10
1	265	1622	6318
2	140	795	3120
3	93	531	2091
4	78	421	1623

As we can clearly see, the the algorithm scales linearly with the number of processors.

Download the program.