A blog of blobs
Image Processing & GFX
GPU-based Gradient Vector Flow using OpenCL
311 months ago
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
1611 months ago
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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Simple Image Processing Library
21 year ago
I do a lot image processing both on images and 3D images / volumes. There exist many image processing libraries out there. Some are big and some are small, but none seems to fit my taste. ITK is one of the major image processing libraries used in my field of research, but this library is, in my opinion, extremly cumbersome. And I can’t be the only one who think so since there has been made an alternative called Simple ITK. There exists many other image processing libraries that tries to be simple to use, but most of them don’t allow you to do volume processing, which I do a lot of. I want a library that allows me to quickly go from an algorithm concept to getting actual pictures on the screen so that I can quickly verify the results. So far I’ve been using Matlab for prototyping image processing algoritmhs, and it have worked quite well, but as I see it Matlab has two major problem: speed and computation and GUI in one thread. A long story short, I’ve made my own Simple Image Processing Library (SIPL) which I now use in my research. I’ve added a short guide here on how to use and install it in case anybody else feel the same as I do and thinks this library could be of any use to them as well. Also, this small little library is still in development so if you have any feedback, suggestions, comments or bug reports please let me know.
Main goals of the library:
- Simple and condensed – Easy to get from an algorithm concept to pictures on the screen
- GUI in seperat thread – Display and explore images interactively while computation is still going on
- Cross-platform – Linux, Windows and Mac compatible
Press more below to see code examples, download and read install instruction.
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Marching Cubes implementation using OpenCL and OpenGL
111 year ago
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.
3D Gradient Vector Flow Matlab Implementation
162 years ago
Gradient Vector Flow (to the right) calculated on the volume to the left.
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. But GVF is also used for detection of tubular structures and skeletonization. In this post I present a simple Matlab implementation of GVF for 3D images which I made because I could not find any online. The implementation is a simple extension of Xu and Prince original 2D implementation found at their website.
Moore Neighbor Contour Tracing Algorithm in C++
143 years ago
This post shows the implementation of Moore’s neighbor tracing algorithm in C++. This algorithm performs what is called contour tracing i.e.
tracing the borders or boundaries of, in this case, a binary image. The two images below illustrates what the algorithm does with a pure black and white/binary image.
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