ColorVideoVDP (CVVDP) is a University of Cambridge developed full-reference video/image quality metric designed to predict how humans perceive distortions (compression, scaling, transmission errors) in video content. It accounts for viewing conditions, display brightness, and color resolution. The model outputs a Just-Objectionable-Difference (JOD) score, where 1 JOD corresponds to a 75% preference over a lower-quality video.

Applications: Joint spatiotemporal assessment of luminance and color distortions, including video streaming, display specification, and design. Visual comparison of results and perceptually-guided video quality optimization.

Key Features of ColorVideoVDP Applied in ClearView

JOD Score: The CVVDP metric maps distortions to JOD units, with 10 representing no difference and lower values indicating increased distortion. JOD units indicate that a one-unit difference corresponds to an  increase in preference, often interpreted as the point where a user can distinguish the higher quality option.

Perceptual Modeling: It calculates the visibility of distortions by accounting for chromatic spatiotemporal contrast sensitivity and cross-channel masking.

Display & View Dependent: In ClearView select from already entered target display types or enter the parameters of a different display type such as display size, resolution, peak brightness, and viewing distance to model a given display’s specifications when making CVVDP metric measurements for both HDR and SDR content.

JOD Score Data Output Types in ClearView:

• • ClearView returns the CVVDP metric JOD score per frame of automatically aligned source to processed video segments similarly to its other full reference metrics by entering the JOD data in a user named text log file along with min, max, and average scores also applied in the log.
  • The ClearView Metric Log Grapher utility generates automatic JOD score per compared frame graphs in PDF format from each test log file saved.
  • If multiple CVVDP test logs are saved in one folder the Metric Log Grapher will provide color coded plots of each JOD test log on one PDF for comparison. A min, max, average bar graph per video sequence tested is provided along with .csv format files of each test for further usage and analysis.
  • ClearView also plays back video in several comparison view modes with its playback cursor positioned at the current frame aligned with a corresponding JOD score graph shown just below the cursor. The current frame score along with the loaded sequence pair’s tested min, max, and average scores are shown to the right of the View Mode selections.

• • Easy GoTo Highest and Lowest score selections as well as Play, Jog +/-, Pause, and frame position via cursor functions are provided with the corresponding uncompressed video being output to a full resolution display.
  • JOD score overlay may be turned on to display the current frame’s JOD score in a low screen position shown in the ClearView GUI Viewport and on the video output.

Distortion Heatmap Feature: ClearView includes the CVVDP heatmap overlay with per pixel distortion intensity applied to the video on HDMI, 12G-SDI, and optional ST 2110 outputs to help users interpret the quality score for areas of deviation from the original in the processed video version of media content.

• • The distortion heatmap settings give the user a highlighting and decision-making tool to understand levels of perceptual aberration that may be significant or subtle versus the original version.
  • Significant differences may be found using the “supra-threshold” setting which corresponds to a difference from 0 to 3 JOD score values mapped as blue to yellow colors.
  • The “threshold” setting shows subtle differences by mapping values between 0 and 1 JOD as green to red colors.
  • A third selection is “raw” with difference values between 0 and 10 mapped to 0-1 range showing black to white.

 

ClearView’s Comparison View Modes: Using ClearView’s view modes also allows the user to toggle between the source and processed version in single full screen output mode or apply both reference and processed pictures to the same output for source versus processed video comparison views. Heatmaps may be turned on or off and may be applied to either or both source (A) and processed (B) versions of tested video.

• • Various selectable comparison view modes include side-by-side, split mirror, seamless split, and A minus B with threshold and color addback.
  • All view modes are interactively zoomable up to 16x, with picture roam and split points adjusted or moved via mouse click and drag while in play or pause modes.
  • The Multiple Outputs selection allows the mapped A and B videos to be output to separate displays with fully synchronized playback control.

The SMPTE ST 2110 standard has been evolving to include encoding functionalities and the first applications are for testing encoding and decoding as applied in ST 2110-22 and also for testing picture and sound quality of encoders that process content from the ST 2110 to another network using MPEG or other compression types targeted for delivery over satellite, terrestrial broadcast transmission, or internet.

Applying the ClearView full reference test systems with new 4K capable ST 2110 network interfaces allows the user to perform a well known technique for testing the network path or encoder processing quality whether it be JPEG XS, HEVC, AV1, or any codec.

• • The user may easily capture video, then feed the original source content chosen for testing into the network while, at the same time, recording the content that has been encoded and decoded as a fully uncompressed sequence to test for quality.
  • Once captured, source and test sequences are automatically aligned with several selective automatic methods.
  • A host of quality metrics may then be applied for testing picture and sound quality of separate vendor codec implementations or testing a varying set of bit rates through the encoding process in order to find the best quality for the required media content, delivery format, and potentially different receiver devices as additional variables.

Record or Import Your A/V Source File or use a pre-loaded one

Play the source test sequence to the device under test (DUT) via baseband interface

Record the output of the DUT via MPEG IP network

Automatically temporally and spatially align source and processed recordings

Calculate quality score closely correlated to human perception
-CVVDP, VMAF, MS-SSIM (on DMOS and MS-SSIM scales), ΔEITP, and Sarnoff JND algorithms

Log and overlay graph each score type automatically with included Metric Log Grapher

View and visually compare the video sequences on one display to verify the score

ClearView® Video Quality Analyzer Products

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Additional Publications