Achieving DSCQS Results Using Advanced Technology
K-WILL eliminates weaknesses of traditional subjective testing.
Using a patented three-layered noise weighting technology,
K-WILL provides the same results as the attentive human eyes.
K-WILL's VP Series enables automated, accurate and real time
video and audio quality analysis for every type of source
material on a frame-by-frame basis. The test result for each
frame is calculated and plotted in a graph with different
colors assigned to highlight different value levels.
3-Layered Noise-Weighting Evaluation
In order to provide users with DSCQS values, K-WILL employs
a patented 3-layered noise-weighting algorithm that calculates
video and audio quality just as human visual perception.
Based on frame activity, we infer the object complexity of
a frame and determine a general noise sensitivity value. This
is based on the concept that higher object complexity causes
weaker focus of the viewer's attention (gaze points) and lower
sensitivity to video noise.
Based on block activity, we infer the degree of "noise
masking" effect within specific regions (= 8 X 8 small
blocks) and determine the degree of noise sensitivity of each
section within the regions. Human eyes tend to be sensitive
to video noise that is overlaid on flat or smooth patterns
where block activity is low, but on the other hand, they are
less sensitive to noise that occur on images such as forests
and trees as the images "mask the noise".
Noise is segregated into high and low frequency ranges by
applying a band-pass-type visual filter.
High Correlation with Subjective Testing Results
Video quality testing by human observers tends to vary in
the test results. Namely, the correlation of the results of
"subjective" tests will not necessarily be 1.00.
The diagram below shows a comparison of test results using
K-WILL's VP products and those based on two executions of
"subjective" testing. The correlation among the
three test results was almost identical, demonstrating VP's
ability to produce test results that are comparable to traditional
Automatic Synchronization of Source and
In order to compare the source and the tested videos, it
is necessary to accurately synchronize the two video signals.
While conventional method attempted synchronization by inserting
a special timing marker in the picture, KWILL's products achieve
synchronization based on the video signal itself ("markerless
synchronization"). As a result, it is possible to automatically
synchronize and analyze video images even as they are transmitted
through broadcasting networks.
The possible range of delay compensation for synchronization
is within 60 frames with a horizontal value of ±24 pixels
and vertical value of ±4 lines.
What is DSCQS?
Video quality has traditionally been measured by human observers.
Known as DSCQS (Double Stimulus Continuous Quality Scale),
this method has been standardized under ITU-R (International
Telecommunications Union-Recommendation) BT-500. Under this
method, picture quality is expressed as a percent from 0 to
100, with 0 indicating no distortion. The higher the value,
the greater the distortion between the original and the tested
While DSCQS provides a good index for quality, this method
requires not only a special testing room, monitors, and video
editing but also a panel of 15 or more human observers. Inevitably,
this type of testing has various limitations such as the inability
to reproduce consistent results and conduct "real-time"
evaluation as well as the difficulty in conducting extended
testing. With K-WILL's technology, it becomes easy to automate