OpenCL

GPU-based Gradient Vector Flow using OpenCL

3
11 months ago
by Erik Smistad in ,

Illustration of Gradient Vector Flow performed on an image. The colors represents the vector direction.

Gradient Vector Flow (GVF) is a feature-preserving diffusion of gradient information. It was originally introduced by Xu and Prince to drive snakes, or active contours, towards edges of interest in image segmentation. However, GVF is also used for detection of tubular structures and skeletonization.

I just recently published an article in the Journal of Real-Time Image Processing entitled “Real-time gradient vector flow on GPUs using OpenCL” describing an optimized OpenCL implementation of Gradient Vector Flow (GVF) that runs on GPUs and CPUs for both 2D and 3D.
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Gaussian Blur using OpenCL and the built-in Images/Textures

16
11 months ago
by Erik Smistad in ,
If used correctly, OpenCL images / textures can give you large speedups on GPUs. In this post, I’ll show you a very short example of how to use OpenCL to blur/smooth an image. The goal is to show how images/textures are used in OpenCL and the benefits of using them.

The source code can be download from by GitHub page.
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Marching Cubes implementation using OpenCL and OpenGL

11
1 year ago
by Erik Smistad in , ,

In a school project I recently created a fast implementation of Marching Cubes that uses OpenCL to extract surfaces from volumetric datasets and OpenGL to render the surfaces on screen. I wrote a paper together with my two supervisors about the implementation and presented it at the Joint Workshop on High Performance and Distributed Computing for Medical Imaging at the MICCAI 2011 conference. Our implementation achieved real-time speeds for volumes of sizes up to 512x512x512 on a standard GPU with 1GB memory. The paper entitled “Real-Time Surface Extraction and Visualization of Medical Images using OpenCL and GPUs” describing the implementation can be downloaded here. The source code of the implementation can be downloaded from my GitHub page.

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OpenCL C++ Utilities

11
1 year ago
by Erik Smistad in

I recently created a small utility library for OpenCL with C++. It consists of a set of function based on the OpenCL C++ bindings to help set up an OpenCL context, compiling OpenCL code and viewing error functions. I hope these functions can be useful for others and I’m planning on adding more utility functions in the future. Note that I haven’t tested it on all platforms yet. Feedback and comments are most welcome.

The source code can be downloaded from my GitHub page.

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Using the C++ bindings for OpenCL

24
2 years ago
by Erik Smistad in

While the OpenCL API is written in C, the OpenCL 1.1 specification also comes with a specification for C++ bindings. In this post I go through how to use the C++ bindings instead of C for the simple example of vector addition from my previous post Getting started with OpenCL and GPU computing.

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Getting started with OpenCL and GPU Computing

119
3 years ago
by Erik Smistad in

OpenCL (Open Computing Language) is a new framework for writing programs that execute in parallel on different compute devices (such as CPUs and GPUs) from different vendors (AMD, Intel, ATI, Nvidia etc.). The framework defines a language to write “kernels” in. These kernels are the functions which are to run on the different compute devices. In this post I explain how to get started with OpenCL and how to make a small OpenCL program that will compute the sum of two lists in parallel.

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