Image Constraint Token
Encyclopedia
The Image Constraint Token (ICT) is a protocol flag that can cause downsampling
of high-definition video
content on Blu-ray and HD DVD
to slightly-better-than-DVD quality video. It is part of the Advanced Access Content System
, the Digital Rights Management
system used in high-definition optical disc formats.
-enabled player, all components in the display chain (including the display panel) must be considered "secure". This security is enforced through the High-bandwidth Digital Content Protection
(HDCP) system, available on some devices which support DVI
and HDMI
video connections. If any components in the display chain do not support HDCP (such as a display connected to the player through analog connections like component
, composite
or S-Video
) and the ICT flag is enabled, the player automatically reduces the high-definition video to the resolution of 960x540 pixel
s before outputting it. Hence, while higher resolution than that of a standard DVD
, the resulting video signal is no longer truly high-definition.
The Image Constraint Token applies on a per disc basis, so that one movie title could have it enabled while another from a different studio could have it disabled. It impacts video only, and has no effect on audio signal quality. Discs with ICT enabled will (theoretically) have it marked on the outside of package, allowing consumers to see if the specific disc has the flag enabled.
Note that ICT in conjunction with HDCP is used to protect the display path over which the video data travels, not the actual data on the disc itself.
ed content. Without content protection, users with the appropriate equipment could easily capture
each and every frame of the film at its full resolution, effectively making a "perfect" copy. Although this danger is greatest for unsecured digital outputs, analog outputs also allow copies to be made, albeit with a potential for slightly reduced quality.
Some HDTV early adopters object to the ICT flag because initial HDTVs did not incorporate HDCP support and thus, if this was activated, these individuals would not be able to enjoy high-definition video from such discs.
Downsampling
In signal processing, downsampling is the process of reducing the sampling rate of a signal. This is usually done to reduce the data rate or the size of the data....
of high-definition video
High-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
content on Blu-ray and HD DVD
HD DVD
HD DVD is a discontinued high-density optical disc format for storing data and high-definition video.Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format...
to slightly-better-than-DVD quality video. It is part of the Advanced Access Content System
Advanced Access Content System
The Advanced Access Content System is a standard for content distribution and digital rights management, intended to restrict access to and copying of the "next generation" of optical discs and DVDs. The specification was publicly released in April 2005 and the standard has been adopted as the...
, the Digital Rights Management
Digital rights management
Digital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...
system used in high-definition optical disc formats.
Operation
When using an AACSAdvanced Access Content System
The Advanced Access Content System is a standard for content distribution and digital rights management, intended to restrict access to and copying of the "next generation" of optical discs and DVDs. The specification was publicly released in April 2005 and the standard has been adopted as the...
-enabled player, all components in the display chain (including the display panel) must be considered "secure". This security is enforced through the High-bandwidth Digital Content Protection
High-Bandwidth Digital Content Protection
High-bandwidth Digital Content Protection is a form of digital copy protection developed by Intel Corporation to prevent copying of digital audio and video content as it travels across connections...
(HDCP) system, available on some devices which support DVI
Digital Visual Interface
The Digital Visual Interface is a video interface standard covering the transmission of video between a source device and a display device. The DVI standard has achieved widespread acceptance in the PC industry, both in desktop PCs and monitors...
and HDMI
High-Definition Multimedia Interface
HDMI is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA...
video connections. If any components in the display chain do not support HDCP (such as a display connected to the player through analog connections like component
Component video
Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...
, composite
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
or S-Video
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...
) and the ICT flag is enabled, the player automatically reduces the high-definition video to the resolution of 960x540 pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s before outputting it. Hence, while higher resolution than that of a standard DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
, the resulting video signal is no longer truly high-definition.
The Image Constraint Token applies on a per disc basis, so that one movie title could have it enabled while another from a different studio could have it disabled. It impacts video only, and has no effect on audio signal quality. Discs with ICT enabled will (theoretically) have it marked on the outside of package, allowing consumers to see if the specific disc has the flag enabled.
Note that ICT in conjunction with HDCP is used to protect the display path over which the video data travels, not the actual data on the disc itself.
Rationale
The use of ICT is an attempt to prevent individuals from creating unauthorized high-resolution copies of copyrightCopyright
Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
ed content. Without content protection, users with the appropriate equipment could easily capture
Video capture
Video capture is the process of converting an analog video signal—such as that produced by a video camera or DVD player—to digital video. The resulting digital data are computer files referred to as a digital video stream, or more often, simply video stream...
each and every frame of the film at its full resolution, effectively making a "perfect" copy. Although this danger is greatest for unsecured digital outputs, analog outputs also allow copies to be made, albeit with a potential for slightly reduced quality.
Some HDTV early adopters object to the ICT flag because initial HDTVs did not incorporate HDCP support and thus, if this was activated, these individuals would not be able to enjoy high-definition video from such discs.