Tag Archives: Intel

Morphological Antialiasing

An Intel research group has put their papers and code up for download. I had asked Alexander Reshetov about his morphological antialiasing scheme (MLAA), as it sounded interesting – it was! He generously sent a preprint, answered my many questions, and even provided source code for a demo of the method. What I find most interesting about the algorithm is that it is entirely a post-process. Given an image full of jagged edges, it searches for such edges and blends these accordingly. There are limits to such reconstruction, of course, but the idea is fascinating and most of the time the resulting image looks much better. Anyway, read the paper.

As an example, I took a public domain image from the web, converted it to a bitonal image so it would be jaggy, then applied MLAA to see how the reconstruction looked. The method works on full color images (though has to deal with more challenges when detecting edges). I’m showing a black and white version so that the effect is obvious. So, here’s a zoom in of the jaggy version:

zoomed, no antialiasing (B&W)

And here are the two smoothed versions:

zoomed, original zoomed, MLAA

Which is which? It’s actually pretty easy to figure: the original, on the left, has some JPEG artifacts around the edges; the MLAA version, to the right, doesn’t, since it was derived from the “clean” bitonal image. All in all, they both look good.

Here’s the original image, unzoomed:

original

The MLAA version:

MLAA

For comparison, here’s a 3×3 Gaussian blur of the jaggy image; blurring helps smooth edges (at a loss of overall crispness), but does not get rid of jaggies. Note the horizontal vines in particular show poor quality:

3x3 Gaussian blur

Here’s the jaggy version derived from the original, before applying MLAA or the blur:

jaggy B&W version

7 Things for July 20th

While at SIGGRAPH I like to look at new books at the booths. One you may wish to check out is Graphics Shaders: Theory and Practice, from AK Peters (or just use “Look Inside” on Amazon). I received a review copy and skimmed through it. If you’re interested in programming in GLSL 1.2 (part of OpenGL 2.1), consider looking at this one. A minor problem is that it’s not quite as up-to-date as the Orange Book (now on OpenGL 3.1), but the difference in core concepts between language versions is not large. The Graphics Shaders book is full color and comes with a lot of GLSL code examples. It has a bias towards scientific visualization, though not so much that it neglects the basics. I particularly enjoyed the chapter on noise, as it gave one of the clearest explanations I’ve seen on the differences between various types of basic interactive noise functions. One or two elements in the book are a little weak – the flowcharts for pipelines are often too small and difficult to read, for example – but all in all this looks like a solid contribution to the field. Don’t expect more elaborate effects, e.g., shadows are not touched upon. It does cover the basics, plus some additional topics like image post-processing (not normally covered in texts I’ve seen). One of the authors wrote a nice learning tool for GLSL, glman, free for download. If you find you like this tool, definitely consider the book.

Another book I noticed recently is Fluid Simulation for Computer Graphics. This is a topic I know little about, I was just interested to see that there’s any book at all. It looks pretty equation-filled, so is definitely for the serious practitioner.

Speaking of fluid simulation, Intel has an article on this topic for games. One of the chief strengths of any publication is that its staff makes a decision based on merit as to what is published and what is culled. So, I have to admit to being leery of anything that says, “Sponsored Feature”, as that means editorial review and decision-making are gone. I tend to err on the side of ignoring such articles (there’s plenty to read already). That said, Intel’s had quite a number of these articles recently, including such topics as instancing, ocean fog, FFT’s for image processing, and quite a few on parallelism.

In the “clearing the queue” category of links, I don’t think I ever pointed out this handy page, which presents all AMD/ATI and NVIDIA presentations at GDC 2009.

There’s now a (not very active, but at least it exists) Microsoft DirectX blog.

On the OpenGL front, NVIDIA has introduced bindless graphics to help avoid L2 cache misses. I will be interested to see how APIs evolve, as the elements in the current APIs that are bottlenecks are not so much CPU or GPU limitations as due to the API constructs themselves.

Thing for the day: an advertisement with interesting stippling.