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Picture quality analyzer uses Human Vision Model

Posted: 20 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:picture quality analyzer? HD video? Human Vision Model?

Tektronix Inc. has unveiled the PQA500 Picture Quality Analyzer, a new-generation picture quality analysis (PQA) tool that incorporates eight new Tektronix patents and integrates what Tektronix touts as the most comprehensive Human Vision Model. The PQA500 tool is said to provide the most complete suite of measurement and diagnostic tools for picture quality analysis including full support of high definition (HD) formats. Video developers and broadcasters can quantify subjective video responses with the PQA500, enabling them to tune their video offerings for differences in format and delivery mechanisms.

"The PQA500 is unique in its ability to compare differing file/video formats, frame rates, bandwidth, viewing conditions and display models," said Todd Biddle, VP for video products at Tektronix. "The instrument enables codec developers and broadcasters to optimize resources while also meeting customer expectations for consistent picture quality regardless of the viewing medium."

Reliable solution
The PQA500 Picture Quality Analyzer provides an automated alternative through practical, efficient and reliable picture quality assessment among HD/SD and low-resolution clips like CIF, and QVGA for codec design and conformance test applications.

The PQA500 tool facilitates this through adaptation to any resolution and frame rate and automatic spatial and temporal alignment of reference and test video clips, even between different video standards. Hence, the perceptual difference may be measured between lower resolution sequences and an original higher resolution SD/HD sequence and vice versa.

The instrument includes integrated signal acquisition, manual and automated measurements through XML scripting, no preset limit to clip lengths or file sizes, and no need for a trigger pattern in the clip to align test to reference video. A GUI provides preconfigured application specific measurements and multiple viewing and results options.

Intuitive model
Using the Human Vision Model, the PAQ500 Picture Quality Analyzer uses quantitative techniques to predict subjective video quality ratings between video of the same video standard, 1,080i and 720p HD, HD and SD, 525-line and 625-line SD, 30fps and 25fps, SD and CIF and HD and CIF, said Tektronix. This capability is a first for the industry, enabling direct support of video re-purposing involving conversion from one video standard to another.

There are 19 calibration parameters incorporated into the PQA500 that serve to fully implement the Human Vision Model. These parameters are formulated based on the data available from thousands of published results of experiments in vision science. The parameters support evaluation and comparison among differing file and video formats, frame rates, viewing conditions, and display models.

The intelligence of the model has been built into the PQA500 through an "adaptive integrator," also known as an adaptive recursive (infinite-impulse response, IIR) low-pass filter. Because human vision adapts to changing conditions in light, display, distance and temporal aspects, changes in sensitivity to video impairments can change subjective rating response dramatically. The adaptive integrator is used to mimic human vision adaptation to accurately predict video quality across many applications.

The PQA500 tool is available immediately for order. Pricing starts at $60,000.

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