Sony XCEI50 Product Brochure (Glossary of Camera Technology) - Page 1

Glossary of Camera terminology Glossary 0 LuxShot: Technique allowing pictures to be shot without visible light. The camera is switched to its infrared sensitivity mode and infrared lighting (built-in to Sony IR sensitive cameras) is used to illuminate the scene. As the picture is only infrared, no significant color information is displayed. The picture looks slightly greenish, like an image intensifier picture. NOTE: In 0 LuxShot mode, the iris remains in a fully open position, and the high-speed shutter feature does not function. 4:4:4 / 4:2:2 / 4:1:1: Indicates the sampling applied to the Y/R-Y/B-Y components of an analog video signal when it is converted into a digital signal. The three numbers indicate the ratio of the sampling rates applied to the individual signals. 4:4:4 indicates that the same sampling rate has been applied to all three signals, 4:2:2 means that the sampling rate of the R-Y and B-Y color difference signals is half that of the luminance signal Y, while 4:1:1 indicates that the sampling rate is one quarter that of the Y signal. AE (Auto Exposure): Combined use of AGC and iris motor control allows shooting in a broad range of lighting conditions. AGC amplifies the video signal in low light conditions, iris reduces it in high light conditions. Motor iris control can be replaced by the CCD IRIS control. AF (Autofocus): Available in cameras equipped with motorized focus, this feature provides automatic adjustment of the focus. AF operates by varying the focus to maximize the high frequency content of the central area of the picture by reference to high luminance and strong contrast elements. In some cameras, AF can be set to High or Low sensitivity modes. AF mode is not recommended for continuous 24-hour operation. See also One-push AF, Interval AF, Zoom triggered AF. AGC (Automatic Gain Control): Circuitry that automatically adjusts the electronic amplification of the video signal to compensate for varying levels of scene illumination. Aliasing: Interference phenomenon which occurs when a sampled signal contains frequencies that are higher than half the sampling frequency. A CCD samples the picture spatially. An optical low-pass filter is used to avoid aliasing, especially in color applications. Aperture correction: Camera signal processing function which adjusts the enhancement of edges of objects in a picture. Aspect Ratio: The ratio of width over height of an image, 4:3 for a standard TV image, 16:9 for wide screen. Asynchronous transmission mode: IEEE 1394 data transmission mode without a guaranteed data delivery time. Used in IEEE 1394 cameras for control functions and reports. ATW (Auto Tracking White balance): In ATW mode, white balance is continuously being adjusted according to the color temperature of the scene illumination. Backlight compensation: Special compensation option in AE (Auto Exposure) mode. When the background is too bright and/or when the subject is too dark, backlight compensation modifies the action of Auto Exposure to make the subject appear clearer. Bayonet mount: Type of camera mount in which there is 38 mm or 48 mm clearance between the lens rear mounting surface and the camera's CCD. Black stretch / Black Compress Control: A function of Digital Signal Processing technology that enables the contrast of the black area of an image to be variable adjusted. The black stretch function emphasizes contrast in the dark areas while black compress enhances or deepens darkness. CCD (Charge Coupled Device): Semiconductor device made of a matrix (or lines) of individual photosensitive elements, called pixels. The optics focus the scene onto the matrix and each pixel accumulates an electric charge proportional to the local intensity of received light and to the integration time. At read out time, all charges are transferred at the same time to an output matrix protected from light, where a sequential reading may take place while a new picture starts integrating. The output matrix size is half that of the sensitive matrix size for interlaced mode CCDs, and the same size for progressive scan CCDs. CCD IRIS: Special operating mode of the electronic shutter of a CCD camera. The shutter timing is automatically adjusted to maintain the same video output level, irrespective of the scene illumination. Can only reduce the camera sensitivity. Allows the use of a fixed iris lens under variable lighting conditions. Often combined with AGC. CCIR: B/W video standard with 625 lines / frame, 2 interlaced fields / frame, 25 frames / second. Monochrome version of PAL. CCU (Camera Control Unit): The CCU provides a means of controlling a remote camera. So that the remote camera can be as small and light as possible, the CCU also includes all electronic circuits that do not have to be fitted inside the remote head, these are typically signal processing circuitry, input/output interfaces and power supply. Chrominance: Color part of the composite video signal. Also called C. Separately transmitted in Y/C (S-video). It is the combination of the two color difference signals (U or R-Y) and (V or B-Y) modulated on to a subcarrier. See also YUV. CHU (Camera Head Unit): In a remote head camera system, the CHU is a small unit that only includes the sensor, its optical interface, the cable coupling to a CCU and the minimum amount of electronic circuitry. C-Mount: Type of camera mount in which there is 17.526 mm clearance between the lens rear mounting surface and the camera's CCD. Composite sync: Combination of the HD and VD in one signal. Commonly used as a synchronizing or genlock signal in B/W systems. Depth of field: Distance between the nearest and farthest points in a scene that are in focus as viewed by a particular lens. Affected by choice of lens focal length and iris aperture. Increases with both decreasing lens focal length and decreasing iris aperture. Donpisha: Means "immediate" in Japanese. CCD sensor shuttering technology for asynchronous shooting of fast moving objects without a time delay. DSP (Digital Signal Processing): Inside a camera, sensor signals must be processed in several steps before they can be displayed / transmitted. Typical processing steps are amplification, gamma correction, black level correction, highlight compression/clipping, edge enhancement, color processing, color balance, color correction, output signal encoding. Picture quality is highly dependent on the accuracy and the stability of these processes. In DSP technology, the sensor signal is converted to digital form after initial amplification, and all processing is achieved digitally, ensuring high quality and no drift. Output signals remain in digital form or are converted back to analog depending on the camera output mode. DynaLatitude Process: A unique feature function available when using Digital Signal Processing (DSP) technology. It manages the contrast of each pixel according to a histogram of video signal level distribution in order to utilize the limited dynamic range of the video signal standard. This function is used in the DXC-390/P camera. Dynamic Contrast Control Plus (DCC+): A function of Digital Signal Processing (DSP) technology that virtually eliminates hue factor distortion - phenomenon that is particularly obvious in extreme high light conditions. The DCC+ function manages video signal data at three levels - brightness, hue and saturation that results in reproduced images with suitable knee correction while virtually eliminating hue factor distortion. This function is used in the DXC-390/P camera. E-Donpisha: Enhanced asynchronous shutter. Available with external and internal synchronization modes. The camera CCD starts to accumulate electrons on receipt of an external trigger pulse. Shutter speed is selected by a switch or menu setting. E-Donpisha - II: Asynchronous shutter mode. Available in external sync mode only. Timing of accumulation and shutter speed are controlled by the external trigger signal. Shutter speed is controlled by the width of the pulse and VD controls the timing for image output. EIA (Electronics Industries Association): B/W video standard with 525 lines / frame, 2 interlaced fields / frame, 30 frames / second. Monochrome version of NTSC video signal. Also referred to as RS-170.