Parallelizing Convolutions

This project aims to apply the Emboss kernel on images in both serial and parallel. Parallel versions use MPI and OpenMP.

This code is for an assignment and is not production grade.

Spreasheet with results (time, speedup and efficiency):

https://docs.google.com/spreadsheets/d/14RXUATwGfS6NzDjerQxIyk-99d9u-4Vin8MdKZ8S0VI/edit?usp=sharing

What to expect

The result should be as below:

Original image:

Processed image:

When running the parallel version, each process will generate part of the final result, as shown below for 4 processes:

Process 0:

Process 1:

Process 2:

Process 3:

How it works

How To

Compile

To compile, run make all

Run in serial

To run the serial version on an example image, run:

./build/serial images/lena.bmp lena_serial.bmp

Run in parallel with MPI

To run a parallel version of the algorithm using MPI with 4 processes, run:

mpirun -n 4 ./build/parallel-mpi images/lena.bmp lena_mpi.bmp

To make each process output its partial result, use verbose as shown below:

mpirun -n 4 ./build/parallel-mpi images/lena.bmp lena_mpi.bmp verbose

Run in parallel with MPI and OpenMP

To run a parallel version of the algorithm using MPI an OpenMP with 4 processes, run:

mpirun -n 4 ./build/parallel-mpiomp images/lena.bmp lena_mpi_omp.bmp

Generate random images

To generate random images with noise for testing purposes, run ./make-images.sh

Run experiments

To run experiments and print average time spent processing images generated in the step above, run fire scripts:

# Serial
./fire.sh

# MPI
./fire-mpi.sh

# OpenMP
./fire-omp.sh

# MPI+OpenMP
./fire-mpiomp.sh

Known bugs

Distorced images with MPI

Problem: When using the MPI version, the final image looks distorted.

Root cause: Processes 0 and N-2 deliver more pixels then they should ahte they are used to assemble the final image.

Resolution date: Probably after the end of this semester when I manage to finish other assignments.

Segfault with MPI and OpenMP

Problem: When using MPI and OpenMP together the application might eventually end unexpectedly.

Root cause: The reason was not found yet.

Future work

I plan to fix bugs and separate the code for Bitmap manipulation from the application code as a lib.