Video monitors display video images from cameras and recorders, often using cathode ray tube (CRT) technology. Industrial units typically have higher resolution that consumer monitors or televisions and can have additional functions such as zooming and multiple signal display. Video monitors can operate in black and white or color. Black and white is monochrome, or grayscale; the image is presented in black, white, and grayscale. The range of colors is generated with varying combinations of different discrete colors. One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.
Important performance specifications to consider when searching for video monitors include horizontal resolution, screen size, and number of video inputs. The horizontal resolution is the maximum number of individual picture elements that can be distinguished in a single scanning line. It is most common to characterize horizontal video resolution corrected for the image aspect ratio, or specify the resolution in the largest circle than can fit in a rectangular image. Thus, for example a 640 x 480 image would be specified as 480 horizontal lines. Screen size refers to the diagonal measurement of image size. The number of video inputs is the maximum number of simultaneous video signal inputs from cameras, recorders, etc.
Video formats used by video monitors include NTSC, PAL, SECAM, RS170, RS330, and CCIR. Color signals are typically RGB, Y PbPr, Y/C (S-video), or composite. RBB is A type of component video output in which red, green, and blue image components are transmitted as separate signals over three separate wires, allowing for full bandwidth for each component. Different synchronization methods are available for RGB. Y PbPr is a component video format in which three signals Y, R-Y, and B-Y, are transmitted via separate cables. S-Video or Y/C output contains two separate signals, luminance (Y) and color (C) transmitted on two separate cables. The C color component is modulated on the same 3.58 MHz subcarrier as it would be for NTSC output, but the bandwidth is not limited as it must be for Composite Output. Composite output format contains the red, green and blue components of the color (C) encoded or compressed, then superimposed on the luminance (Y) on a single signal. The RGB signals are decoded and reconstructed for image display, but the bandwidth limiting of the signal compression limits the subsequent color faithfulness.
Video monitors may have multiple display support. The multiplexer can transmit multiple images simultaneously to monitor or recorder. Common multiple display options include picture-in-picture (PIP), quad, nine, and sixteen. Common features for video monitors include alarms, zoom capability, front control panel, switching or multiplexing, and audio capability. Mounting options for video monitors include desktop or stand-alone, panel or chassis mount, rack mount, and DIN rail. The monitor power can be 115 VAC or 230 VAC.