Image processing

The Panorama Factory photo stitching
The Panorama Factory handles an increasingly popular image processing task: joining together multiple images to create a wide-aspect panorama. This task can require lots of memory and can be computationally intensive, so The Panorama Factory comes in a 64-bit version that's widely multithreaded. I asked it to join four pictures, each eight megapixels, into a glorious panorama of the interior of Damage Labs.

In the past, we've added up the time taken by all of the different elements of the panorama creation wizard and reported that number, along with detailed results for each operation. However, doing so is incredibly data-input-intensive, and the process tends to be dominated by a single, long operation: the stitch. So this time around, we've simply decided to report the stitch time, which saves us a lot of work and still gets at the heart of the matter.

Once more, the Athlon II X4 635's four real cores grant it the edge over the Core i3-530. Six seconds of destiny! The Pentium E6500 outperforms the Athlon II X2 255, though.

picCOLOR image processing and analysis
picCOLOR was created by Dr. Reinert H. G. Müller of the FIBUS Institute. This isn't Photoshop; picCOLOR's image analysis capabilities can be used for scientific applications like particle flow analysis. Dr. Müller has supplied us with new revisions of his program for some time now, all the while optimizing picCOLOR for new advances in CPU technology, including SSE extensions, multiple cores, and Hyper-Threading. Many of its individual functions are multithreaded.

Recently, at our request, Dr. Müller graciously agreed to re-tool his picCOLOR benchmark to incorporate some real-world usage scenarios. As a result, we now have four new tests that employ picCOLOR for image analysis. I've included explanations of each test from Dr. Müller below.

Particle Image Velocimetry (PIV) is being used for flow measurement in air and water. The medium (air or water) is seeded with tiny particles (1..5um diameter, smoke or oil fog in air, titanium dioxide in water). The tiny particles will follow the flow more or less exactly, except may be in very strong sonic shocks or extremely strong vortices. Now, two images are taken within a very short time interval, for instance 1us. Illumination is a very thin laser light sheet. Image resolution is 1280x1024 pixels. The particles will have moved a little with the flow in the short time interval and the resulting displacement of each particle gives information on the local flow speed and direction. The calculation is done with cross-correlation in small sub-windows (32x32, or 64x64 pixel) with some overlap. Each sub-window will produce a displacement vector that tells us everything about flow speed and direction. The calculation can easily be done multithreaded and is implemented in picCOLOR with up to 8 threads and more on request.

All of picCOLOR's results are indexed against a reference system, based on a Pentium III 1GHz, whose performance equals a score of 1.0 in each test. For instance, in the Particle Image Velocimetry test above, the Core i7-975 Extreme is a staggering 36.2 times faster than the PIII 1GHz, and even the Pentium 4 670 offers 4.7 times the speed.

Real Time 3D Object Tracking is used for tracking of airplane wing and helicopter blade deflection and deformation in wind tunnel tests. Especially for comparison with numerical simulations, the exact deformation of a wing has to be known. An important application for high speed tracking is the testing of wing flutter, a very dangerous phenomenon. Here, a measurement frequency of 1000Hz and more is required to solve the complex and possibly disastrous motion of an aircraft wing. The function first tracks the objects in 2 images using small recognizable markers on the wing and a stereo camera set-up. Then, a 3D-reconstruction follows in real time using matrix conversions. . . . This test is single threaded, but will be converted to 3 threads in the future.

Multi Barcodes: With this test, several different bar codes are searched on a large image (3200x4400 pixel). These codes are simple 2D codes, EAN13 (=UPC) and 2 of 5. They can be in any rotation and can be extremely fine (down to 1.5 pixel for the thinnest lines). To find the bar codes, the test uses several filters (some of them multithreaded). The bar code edge processing is single threaded, though.

Label Recognition/Rotation is being used as an important pre-processing step for character reading (OCR). For this test in the large bar code image all possible labels are detected and rotated to zero degree text rotation. In a real application, these rotated labels would now be transferred to an OCR-program - there are several good programs available on the market. But all these programs can only accept text in zero degree position. The test uses morphology and different filters (some of them multithreaded) to detect the labels and simple character detection functions to locate the text and to determine the rotational angle of the text. . . . This test uses Rotation in the last important step, which is fully multithreaded with up to 8 threads.

The Core i3-530 takes three of the four real-world tests from the Athlon II X4 635. The Core i3 looks to be slightly superior for this sort of image analysis. Meanwhile, though, the Athlon II X2 255 snags three of four over the Pentium E6500, and the fourth is a tie.

picCOLOR's synthetic tests measure a number of the program's individual functions, and the program then computes an average score, again indexed versus a 1GHz Pentium III. This should be a pretty good index of overall image processing performance. Although the Athlon II X4 635 comes out ahead of the Core i3-530, the gap between the processors remains thin.

Image handling looks to be one of those areas, much like our 3D gaming tests, where the competing CPUs from Intel and AMD are at approximate performance parity. Since these image processing programs are nicely multithreaded wherever possible, that's quite an accomplishment for the dual-core Core i3-530—although we've come to expect such feats from Intel's latest architecture.