A frame grabber is an electronic device that captures (i.e., "grabs") individual, digital still frames from an

analog video Video is an electronic medium for the recording, copying Copying is the duplication of information or an artifact based on an instance of that information or artifact, and not using the process that originally generated it. With analog f ...

signal or a

digital video Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...

stream. It is usually employed as a component of a

computer vision Computer vision is an interdisciplinary scientific field that deals with how computers can gain high-level understanding from digital images or videos. From the perspective of engineering, it seeks to understand and automate tasks that the hum ...

system, in which

video frame In filmmaking, video production, animation, and related fields, a frame is one of the many ''still images'' which compose the complete ''moving picture''. The term is derived from the historical development of film stock, in which the sequentia ...

s are captured in digital form and then displayed, stored, transmitted, analyzed, or combinations of these. Historically, frame grabber

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slo ...

s were the predominant way to interface cameras to PCs. Other interface methods have emerged since then, with frame grabbers (and in some cases, cameras with built-in frame grabbers) connecting to computers via interfaces such as

USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad v ...

, Ethernet and IEEE 1394 ("FireWire"). Early frame grabbers typically had only enough

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...

to store a single digitized video frame, whereas many modern frame grabbers can store multiple frames. Modern frame grabbers often are able to perform functions beyond capturing a single video input. For example, some devices capture audio in addition to video, and some devices provide, and concurrently capture frames from multiple video inputs. Other operations may be performed as well, such as

deinterlacing Deinterlacing is the process of converting interlaced video into a non-interlaced or Progressive scan, progressive form. Interlaced video signals are commonly found in analog television, digital television (HDTV) when in the 1080i format, some D ...

, text or graphics

overlay Overlay may refer to: Computers *Overlay network, a computer network which is built on top of another network *Hardware overlay, one type of video overlay that uses memory dedicated to the application *Another term for exec, replacing one process ...

, image transformations (e.g., resizing, rotation, mirroring), and conversion to

JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...

or other compressed image formats. To satisfy the technological demands of applications such as radar acquisition,

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...

and

remote guidance Remote guidance, in the medical context, refers to the supervision or guidance of a medical task, usually a procedure or test, from a remote location. This falls in the realm of real time telemedicine applications. By way of example, a radiologi ...

, some frame grabbers can capture images at high frame rates, high resolutions, or both.

Circuitry

Analog frame grabbers, which accept and process analog video signals, include these circuits: * Input signal conditioner that buffers the analog video input signal to protect downstream circuitry *

Video decoder A video decoder is an electronic circuit, often contained within a single integrated circuit chip, that converts base-band analog video signals to digital video. Video decoders commonly allow programmable control over video characteristics such as ...

that converts SD analog video (e.g.,

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

SECAM SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

) or HD analog video (e.g., AHD, HD-TVI, HD-CVI) to a digital format Digital frame grabbers, which accept and process digital video streams, include these circuits: * Digital video decoder that interfaces to and converts a specific type of digital video source, such as

Camera Link Camera Link is a serial communication protocol standard''Specifications of the Camera Link Interface Standard for Digital Cameras and Frame Grabbers, Version 1.1'' Automated Imaging Association, Jan 2004 designed for camera interface applications b ...

CoaXPress CoaXPress (CXP) is a digital interface standard developed for high speed image data transmission in machine vision applications. The name is a portmanteau of 'express' (as in express train) and 'coaxial' to emphasize CoaXPress is faster than other ...

DVI Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a comp ...

GigE Vision GigE Vision is an interface standard introduced in 2006 for high-performance industrial cameras. It provides a framework for transmitting high-speed video and related control data over Ethernet networks. The distribution of software or development, ...

LVDS Low-voltage differential signaling (LVDS), also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial signaling standard. LVDS operates at low power and can run at very high speeds ...

RS-422 RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance that specifies electrical characteristics of a digital signaling circuit. It was meant to be the foundation of a suite of standards that ...

, or SDI Circuitry common to both analog and digital frame grabbers: * Memory for storing the acquired image (i.e., a

frame buffer A framebuffer (frame buffer, or sometimes framestore) is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Modern ...

) * A bus interface through which a processor can control the acquisition and access the data * General purpose I/O for triggering image acquisition or controlling external equipment

Applications

Healthcare

Frame grabbers are used in medicine for many applications, including

telenursing Telenursing refers to the use of information technology in the provision of nursing services whenever physical distance exists between patient and nurse, or between any number of nurses. As a field, it is part of telemedicine, and has many points ...

and

. In situations where an expert at another location needs to be consulted, frame grabbers capture the image or video from the appropriate medical equipment, so it can be sent digitally to the distant expert.

Manufacturing

"Pick and place" machines are often used to mount electronic components on circuit boards during the circuit board assembly process. Such machines use one or more cameras to monitor the robotics that places the components. Each camera is paired with a frame grabber that digitizes the analog video, thus converting the video to a form that can be processed by the machine software.

Network Security

Frame grabbers may be used in security applications. For example, when a potential breach of security is detected, a frame grabber captures an image or a sequence of images, and then the images are transmitted across a digital network where they are recorded and viewed by security personnel.

Personal Use

In recent years with the rise of personal video recorders like camcorders, mobile phones, etc. video and photo applications have gained ascending prominence. Frame grabbing is becoming very popular on these devices.

Astronomy & Astrophotography

Amateur astronomers and astrophotographers use frame grabbers when using analog "low light" cameras for live image display and internet video broadcasting of celestial objects. Frame grabbers are essential to connect the analog cameras used in this application to the computers that store or process the images.

References

{{Reflist Computing input devices Computer graphics