PQA600A Datasheet, PDF (5/19 Pages) List of Unclassifed Manufacturers – Picture Quality Analysis System

Picture Quality Analysis System — PQA600A
E: Reference
G: PSNR Map
F: Test
Comparison of Predicted DMOS with PSNR
In the example above, Reference (E) is a scene from one of the VClips
library files. The image Test (F), has been passed through a compression
system which has degraded the resultant image. In this case the
background of the jogger in Test (F) is blurred compared to the Reference
image (E). A PSNR measurement is made on the PQA600A of the
difference between the Reference and Test clip and the highlighted white
areas of PSNR Map (G) shows the areas of greatest difference between the
original and degraded image. Another measurement is then made by the
PQA600A, this time using the Predicted DMOS algorithm and the resultant
Perceptual Difference Map for DMOS (H) image is shown. Whiter regions
H: Perceptual Difference Map for DMOS
in this Perceptual Contrast Difference map indicate greater perceptual
contrast differences between the reference and test images. In creating the
Perceptual Contrast Difference map, the PQA600A uses a human vision
system model to determine the differences a viewer would perceive when
watching the video.
The Predicted DMOS measurement uses the Perceptual Contrast
Difference Map (H) to measure picture quality. This DMOS measurement
would correctly recognize the viewers perceive the jogger as less degraded
than the trees in the background. The PSNR measurement uses the
difference map (G) and would incorrectly include differences that viewers
do not see.
www.tektronix.com 5