raster scan


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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).
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References in periodicals archive ?
Instead of using conventional raster scan pattern, proposed architecture uses z scan pattern, to read 16 pixels at a time from memory as shown in Figure 4.
The VQ index table T = {[T.sub.ij]}, where 0 [less than or equal to] i [less than or equal to] H/hs - 1, 0 [less than or equal to] j [less than or equal to] W/ws - 1, and 0 [less than or equal to] [T.sub.i,j] [less than or equal to] N - 1, is scanned in raster scan order for encoding and embedding.
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.
For the raster scan, RSDs of 3-14% for [63.sup.]Cu/[12.sup.]C and [sup.65]Cu/[sup.12]C instead of 8-19% for [sup.63]Cu and [sup.12]Cu, and 5-18% for [sup.64]Zn/[sup.12]C and [sup.66]Zn/[sup.12]C compared with 7-23% for [sup.64]Zn and [sup.66]Zn were achieved, whereas the line scan was again significantly more precise with RSDs of 2-3% or 2-5% for [sup.63]Cu/[sup.12]C and [sup.65]CU/[sup.12]C or [sup.64]Zn/[sup.12]C and [sup.66]Zn/[sup.12]C, respectively.
A conventional raster scan is produced by sweeping a small spot of light across the screen to form a scan line and drawing successive scan lines from the top to the bottom of the screen.
Our proposed method processes VQ indices of the index table in a raster scan order.
Ten days later, 56% of the lesions were identified as MVL in color fundus photos (Figure 8(c)) compared to 80% identified using OCT raster scans.
The screen display can be generated with a raster scan, as shown in Figure 1, or by an array, as shown in Figure 2.
The modes include up to 20 discrete or 401 evenly-spaced frequencies, multiple parameters and batch mode processing, of which all can be operated in single axis or raster scan modes.
The raster scan covers an angular area in parallel lines, as shown in Figure 1.