Video display accessory that generates a near-HDTV image from standard NTSC video by combining the interlaced fields into progressive frames and then doubling the number of lines in those frames through a process of interpolation. nterlaced video works by displaying two fields for every frame. The first field displays all the odd lines of a complete video image (one, three, five, seven, etc.). The second field displays the even lines (two, four, six, eight, etc.). Thus, only half the picture is actually displayed every 1/60 second creating a full frame 30 times per second. ine doublers work by combining the odd and even lines of each field and creating full frames out of the fields. This effectively doubles the lines in a given field hence the term line doubling. Instead of an interlaced image, the line doubler combines the fields and produces a progressive scan image that paints every line in the picture in order (one, two, three, four, etc.). Each doubled field, essentially a complete frame, is then projected 60 times per second. The line quadrupler then takes this one step further by doubling the number of lines in each doubled field. If a progressive, doubled field from a line doubler has 480 lines, then the quadrupler doubles those 480 lines to 960 horizontal lines of resolution. oubling the already doubled lines is accomplished through a process of interpolation. The line quadrupler takes the line-doubled image and generates an additional line to go between each line already present from the video signal. This process generates additional lines essentially from a best guess by analyzing the lines above and below and determining what would logically fit in between. The newly generated or interpolated lines are then inserted into the field resulting in a quadrupling of the original number of lines present in the field. ine quadrupled video results in an image near that of HDTV with its 1,080 horizontal lines (of course, HDTV is all digital with superior color, accuracy, detail, very little distortion and 1,080 lines of actual picture detail instead of “best guess” lines making HDTV superior). Line quadruplers, however, are very complex and expensive, even more so than line doublers. They must contain circuitry to save fields and combine then in the proper way to create progressive, doubled fields. This task is difficult enough by itself, but the nature of interlaced fields creates additional difficulties. Often the fields containing the odd lines and those containing the even lines do not properly match up. When this happens, the doubled image combining the odd and even lines is jagged and distorted. Line doublers and line quadruplers must correct for this misalignment and also for movement between fields in order to create an image that is of high quality. The quadruplers then must also contain circuitry to generate the additional lines to double the doubled fields (the interpolation circuitry). ue the complexity involved, line quadruplers are expensive and are not mainstream products. Additionally, line quadruplers must be used with graphics grade projectors. These types of projectors have the necessary scan rate to be able to paint the additional lines in the image (a line doubler requires twice the scan rate of a plain, interlaced video image while a quadrupler requires four times the scan rate and thus cannot be used with most televisions or projectors). However, a quality line quadrupler creates the best image available from NTSC analog video programs and is superior to everything but true HDTV.