ISO/IEC 29170-2:2015 情報技術—高度な画像コーディングと評価—パート2：ほぼロスレスコーディングの評価手順 | ページ 2

Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, 1. In particular the different approval criteria needed for the different types of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, 2 (see www.iso.org/directives ).

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents ).

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The committee responsible for this document is ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.

ISO/IEC 29170 consists of the following parts, under the general title Information technology — Advanced image coding and evaluation:

• Part 1: Guidelines for coding system evaluation (forthcoming)
• Part 2: Evaluation procedure for visually lossless coding

Introduction

This International Standard normalizes a procedure to evaluate coding systems by subjective methods. The procedure is particularly useful for evaluating lightly compressed coding systems used, for instance, in display stream compression where a source compresses image data sent to a display. Examples of display streams include but are not limited to a wired link between a set-top box unit and a television or between a mobile host graphics processor and a display panel module in a mobile appliance. Viewers of these displays should be unaware that a coding system is employed in the device or system. A coding system will be considered visually lossless if the test results meet a pre-defined acceptable quality level demonstrated by the performance criteria described in this Specification under the viewing conditions specified and media sets provided.

Appliances that may require visually lossless performance for compressed display streams include: computer monitor displays, televisions, mobile phone and tablet displays. Data compression for these systems allows existing display links to carry more display data than is possible with uncompressed image streams or to reduce system power consumption or both.

The types of coding systems tested by this procedure may have the following properties:

• a) The presence of a coding system should be undetectable to a user who is viewing the display.
• b) The coding system operates in real-time, with negligible latency, low complexity hardware and minimal memory in both the encoder and the decoder.

This procedure builds on prior standardization and best practices embodied in ISO 3664, ISO 20462-2 and ISO/IEC TR 29170-1.

1 Scope

This Technical Specification normalizes evaluation and grading of a light coding system used for displays and display systems, but is independent of the display technology. This procedure measures whether an observer can distinguish between an uncompressed reference and the reconstructed image to a pre-determined, statistically meaningful level.

The procedure compares individual images with two possible forced choice comparison test methods. This procedure relies on subjective evaluation methods designed to discern image imperfections on electronic colour displays of any technology or size.

Image selections for testing a specific coding system has bearing on the results this procedure will yield, but specific images required for testing are not within scope, excluding an informative annex describing self-test certification. Image categories may vary between end-usage products. For example, content relevant to television manufacturers may or may not be relevant to computer display manufacturers. Due to the nature of this procedure as a visual psychophysical test, observer's age is considered a meaningful parameter of the results.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

Bibliography