raster scan


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.

raster scan

Displaying or capturing a video image line by line. Computer monitors and TVs use this method whereby electrons are beamed (scanned) onto the phosphor coating on the screen a line at a time from left to right starting at the top-left corner. At the end of the line, the beam is turned off and moved back to the left and down one line, which is known as the "horizontal retrace." When the bottom-right corner is reached, the gun is returned to the top-left corner, known as the "vertical retrace." For TV signals, these "flyback" periods in which the electron beam is moved to a different line are also called the "horizontal" and "vertical blanking intervals."

Video Is the Reverse
Capturing video images uses the same raster scan sequence as the display, but in reverse. Instead of sending electrons to a material that creates light, light is directed to a material that holds a charge, and the charge is turned into an electronic signal. The first video cameras used a vacuum tube with a light-sensitive plate at one end. Subsequently, CCD and CMOS chips replaced the tube. See CRT, CCD sensor, CMOS sensor and rasterize.


Raster Scan Tracing
Starting at the top-left of the screen and going to the bottom-right, the electron beam is turned on a line at a time (1), then turned off to go back to the next line (2), then off once again to go back up to the top (3).
References in periodicals archive ?
Top-left: digital RGB image of the area of scan; top-right: merged risk probabilities from depth data; bottom-left: image of gas concentration using raster scan (old strategy); bottom-right: image of gas concentration after inspection using proposed strategy.
In this section, the mechanism of the information leakage of the input operations using button images on touch screen monitor was discussed based on the relationships between the color of the button image in the display image, the corresponding analog voltages of the RGB signals, the emitted signal by the analog voltage variations of the RGB signals in the raster scan, the detected component of the emitted signal in the reception signal, and the grayscale shading in the reconstructed display image.
5% for zinc were achieved with a line scan, whereas with a raster scan the RSDs were significantly higher (0.
A field scan direction was selected at random by the computer, and a raster scan was presented at a frequency above the FFF (90 Hz) for 5 s.
The laser beam must be moved along in a raster scan, much like that used on a TV screen.
Etec's new ALTA 4000 extends the success of the ALTA system's industry-leading, multi-beam raster scan laser architecture to the 130nm device generation, combining superior line resolution with the fastest write times and throughput.