1. picture quality analysis for evaluation of digital video

8/12/2019 1. Picture Quality Analysis for Evaluation of Digital Video

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Presented by:

Picture Quality Analysis for Evaluation of

Digital Video EquipmentReference Test Analysis


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26 November 20072Picture Quality Analysis for Evaluation of Digital Video Equipment

Human Vision Standards

ITU T J.144 - Objectiveperceptual video quality

measurement techniques fordigital cable television in thepresence of a full reference

ITU-R BT.500 - Methodology forthe subjective assessment of thequality of television pictures


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Human Vision Models Various Resolutions

Various Video Formats &Frame Rates

Conversion betweenResolutions

1920x1080

1280x720

720x576 720x486CIF352x288


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Human Vision Models Types of defects


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Human Vision Models Different Viewing Conditions

HandheldPhone

CRT

DLP

LCD

Home

Theater


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PQA500 Picture Quality Analysis

Fast, Accurate, Repeatable, ObjectivePicture quality measurement

Picture quality measurement basedon Human Vision System Model. DMOS & PQR

Picture quality comparison across

different resolutions and frame rates HD, SD, CIF

Attention/Artifact weightedmeasurement

Automatic temporal and spatialalignment


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Simulation System Diagram

Display Model Types of display CRT, LCD, DLP Types of Monitor Broadcast, Consumer,

Computer, Custom

View Model

Viewing Distance Ambient Luminance Spatial Alignment

Perceptual Difference Typical, Expert, Custom

Objective Maps Attention Model - Motion, Center,

People Foreground, Contrast, Color,Shape, Size

Summary Node Measurement Results.

DisplayModel

ViewModel

PerceptualDifference

ObjectiveMaps

SummaryNode


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Applications

CODEC Designer, Video manufacturer Debugging the algorithm, video processing

Investigate improvement

Optimize algorithm to specific

application/contents

R&D division in Broadcaster System / Component Evaluation

Evaluate total system performance

Decide system parameters for each content typeor application

Monitor the system condition

Content Provider Investigate improvement

Evaluate picture quality of edited material Provide evidence for final content quality to

clients


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PQA500 User Interface

Test

MapsGraphs

Reference


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Measurements Types

Double- Ended Require both a Reference and Test

sequence of the video material

DMOS PQR

PSNR

Single Ended Require a test sequence of the

video material

Attention Model

DC Blockiness

Reference Test


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Picture Quality Measurements - PSNR

PSNR Peak Signal to NoiseRatio

Provides a quick check of possible errors PSNR shows the RMS ratio between the

peak signal amplitude and the noiseaccompanying the signal

PSNR is not a direct prediction of what

human viewers will perceive Scale expressed in dB

No difference between Ref & Test = Infinite

Good Quality = Higher dB value

Poor Quality = Lower dB value

Brighter areas in the image map showthe greatest amount of degrade


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Picture Quality Measurements - PQR

PQR Picture Quality Rating

Developed for the PQA200/300

Based on JND Algorithm Just Noticeable Difference Absolute Difference Measurement

Scale No difference between Ref & Test = 0

Good Quality = Low Number

Poor Quality = High Number PQR = 1

50% of viewers will notice a difference


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Picture Quality Measurements - DMOS

DMOS - Difference MeanOpinion Score

Measurement described by ITU-RBT.500

Evaluates worst case results conditionedby a training sequence

Scale

No difference between Ref & Test = 0 Good Quality = Lower number

Poor Quality = Higher number


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PSNR vs. Perceptual Difference

Reference Test

PSNR Perceptual Difference

PSNR shows the differences between the images (reference and test clip)

Perceptual difference shows how the viewer perceives the differences between

the images, this is extremely useful in evaluating the picture quality of the clip


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Attention Model

Reference

The Attention model predicts the eyes attention within the image Highlighted regions show the eyes focus of attention.

For instance more focus on the jogger. Less attention is paid to the twoother walkers.

This model can be used in conjunction with other measurements andprovide a weighting to PSNR or Predicted DMOS.

Useful to optimize the algorithm for Sports program.

Attention Map


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Attention Model Weighting

PSNR Measurement withAttention Model Weighting


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Attention Model Weighting

Blurring

Ringing/Mosquito Noise

Edge Blockiness

DC Blockiness

Blockiness

Blurring

Ringing


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Picture Quality Measurement - Blockiness

Blockiness Measurement


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Picture Quality Measurement - Blurring

Blurring Measurement


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Picture Quality Measurement - Ringing

Ringing Measurement


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PQA Measurement Application Codec Design

Initial Software Design Develops MPEG Algorithm Software Test Environment

YUV Reference File

Software Conversion of YUV file viaSoftware Codec producing YUV test file

Transfer of Reference & Test YUV filesto PQA500

PQA500 measurement of PSNR andDMOS

Allows software development team toquickly evaluate various algorithms

Provides users with verification thatsoftware changes to the algorithmimprove picture quality.

XML Scripting allows PQA500 to batchprocess multiple test

ReferenceYUV File

Test YUV File

1100110000100101101101110111

Software Algorithm


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PQA Measurement Application Codec Design

Hardware and Software Testing

ReferenceYUV File

FileServer

Record toServer

MTX100BCapture

MPEG Stream

ExtractedTest YUV FileMTS4EA

SoftwareExtract of Video

To YUV file

SDIO/P

ReferenceCaptureSDI O/P

PQA500

MPEGTransport

Stream

MPEG

Encoder

MPEG

Decoder

TestCapture

SDIO/P


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Picture Quality Measurement - Analysis

First Compression Algorithm


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After several iteration theperformance of the algorithmhas been improved


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Picture Quality Measurement Picture Quality

Measure A Measure B

Measure C Measure D


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Picture Quality Measurement - Graph Results DMOSMeasure A DMOS Measure B DMOS

Measure C DMOS Measure D DMOS


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Picture Quality Measurement - Graph Results PSNRMeasure A PSNR Measure B PSNR

Measure C PSNR Measure D PSNR


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Picture Quality Measurement - Results

PQA Measurement results are formatted as CSV files

Allows for multiple measurements to be compared in a spreadsheetprogram

DMOS Measurements CODEC

0

10

20

30

40

50

60

70

80

90

100

1 24 47 70 93 116 139 162 185 208 231 254 277 300 323 346 369 392 415 438 461 484

FRAMES

DMO

DMOS Measure A

DMOS Measure B

DMOS Measure C

DMOS Measure D


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Picture Quality Measurement -Comparison


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Picture Quality Measurement -Comparison

Mix mode

Allows mix percentage between:

Reference

Test

Map

Allows frame by frame comparison


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PQA Measurement Application STB Testing

ReferenceYUV File

ExtractedReferenceYUV File

MTS4EASoftware

Extract of Video

To YUV file

PQA500

MPEGEncoded

File

MPEGEncoded

File

Set-Top BoxRF

O/P

TestCapture

SDIO/P

I/OInterfaceConversion

To SDI


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PQA Measurement Application DVD Player

ReferenceYUV File

ExtractedReferenceYUV File

MTS4EASoftware

Extract of Video

To YUV file

PQA500

MPEGEncoded

File

MPEGEncoded

File

DVDSource

Material

TestCapture

SDIO/P

I/OInterfaceConversion

To SDI

DVD Player


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Picture Quality Measurement Broadcast Lab

Broadcast Material converted tovarious video formats

HD Broadcast

SD Broadcast

MobilePhone

Broadcast

HD to SDDown Conversion

Down Conversion&

MPEGConversion

Broadcast Applications

Up / Down Conversion HD to SD & SD to HD

MPEG Codec Evaluation Suitable Bit Rate

Mobile Broadcast Analysis

1920x1080or

1280x720

720x576or

720x486

320x180


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Picture Quality Measurement Cross Conversion

PQA500 up converts test image to match reference image size

In this case there will be large difference between Ref & Test

1920x1080

or1280x720

320x180

Reference

Test


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Picture Quality Measurement Cross Conversion

PQA500 down converts test image to match reference image size

In this case there will be small difference between Ref & Test

1920x1080

or1280x720

320x180

Reference

Test


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HD 1280x720 compared to aCIF 320x180 resolution.


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Picture Quality Measurement Picture Quality

Measure A1 Measure B1

Measure C1 Measure D1


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Picture Quality Measurement - Graph Results DMOSMeasure A1 DMOS Measure B1 DMOS

Measure C1 DMOS Measure D1 DMOS


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Picture Quality Measurement - Graph Results PSNRMeasure A1 PSNR Measure B1 PSNR

Measure C1 PSNR Measure D1 PSNR


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Summary

The PQA500 provides an objective picture quality measurement

Standard Measurements PSNR Peak Signal to Noise Ratio

PQR Picture Quality Rating

DMOS Difference Mean Opinion Score

Attention Weighted measurements

MPEG Defect Measurements Blockiness, Blurring, Noise

Suitable for a variety of measurement applications Codec Design

Consumer Applications, - Set Top Box, DVD player

Broadcast Applications - HD, SD and low resolutions

Mobile applications Phone, Internet


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Further Information

PQA500 Data Sheet

Application Note 25W-20965

Human Vision Model TechnicalBrief

PQA500 Product technicalreference

www.tek.com


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MUCHAS GRACIAS

Ing. Rafael Siciliano

Presidente Lade Profesional S.A.

[email protected]

Para toda consulta o informacin sobre Mediciones entre HDTV, SDI, Analgico

y sobre Sistemas de IPTV, Enlaces Satelitales, o Laboratorio, por favor contactarse a:

[email protected]

Para mas informacin sobre Telecomunicaciones, Broadcast, Video y Cursos

Visite nuestro site: www.ladeprofesional.com.ar

Av. Segurola 1879 (C1407AOK)Buenos Aires, ArgentinaTel.: (54-11) 4639-8939

Fax: (54-11) 4639-8943

E-mail: [email protected] Site: www.ladeprofesional.com.ar

1. picture quality analysis for evaluation of digital video

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