These are simpler in structure and consist, in addition to protective and other interlayers, of a film base, carrying a filter raster, and a black-and-white emulsion layer.
The raster consists of sequences of very narrow red, green, and blue transparent filter lines (up to 1,800 lines per inch) through which the light from the lens passes before it reaches the emulsion layer.
In the late 1970s and '80s raster graphics, derived from television technology, became more common, though still limited to expensive graphics workstation computers.
The removal of raster lines and halftone dots is accomplished with this type of filter.
Hence, if the filter is an aperture centred at one of these locations so that only one of the periodic elements is allowed to pass, then the raster periodicity is removed, but the scene information is retained (see Figure 9).
Because of the presence of the filter elements everywhere in the image, additive colour transparencies are much denser than subtractive ones; at high magnification the filter raster pattern may also become visible.
The displays were essentially modified oscilloscopes, and vector graphics were used because the memory that would be needed for displaying raster graphics, or bit-mapped graphics, was too expensive.
The diffraction pattern consists of a periodic distribution with a periodicity reciprocally related to the raster periodicity.
Raster graphics represents images by bitmaps stored in computer memory and displayed on a screen composed of tiny pixels.
Since the 1990s, raster graphics has become ubiquitous.
This process is also widely used in laser printers, in which the photoconductor is exposed to a digitally controlled on-and-off laser beam that is raster scanned (like the electron beam in a television tube) over the photoconductor surface.
