Improving Apparent Bandwidth of Refresh Displays

Improving Apparent Bandwidth of Refresh Displays

      Disclosed is a process to improve picture quality on a
display device beyond that possible by algorithms which optimize a
picture for a fixed display grid.

      Given a refresh-based display system in which more information
is available for each frame than can be displayed, (1) a separate
picture is computed for succesive frames, on the assumption that the
display grid will be slightly shifted, either horizontally or
vertically or both, and (2) the display grid is indeed shifted by
that amount.

      This mechanism succeeds in increasing the apparent resolution
of the display system, due to the viewer seeing the summation of the
shifted images, and reduces Moire patterns and other artifacts of the
interaction between a static grid and a static picture.  The
technique can be used in the presence or absence of anti-aliasing
techniques [1,2] and in the presence or absence of scanline
interlacing.

      This paragraph summarizes the 1-bit, 1-dimensional algorithm.
Figure 1(a) shows a section of one line of a display supporting data
changes once every T time units, displaying a shape computed to 1
bit.  The true shape actually lies just to the left of the displayed
shape.  A second frame is displayed, slightly shifted with respect to
the first.  Successive frames may shift the display grid by different
amounts, but all within 1/2-T of the original grid.  Figure 1(b)
shows two successive frames.  Under reasonable viewing conditions,
the eye integrates these two images, seeing a single object placed
between the two displayed ones.

      In the general case, there is a 2-dimensional output sample
grid, as shown in Figure 2 (solid lines).  We can assume that the
picture to be displayed is filtered by reasonable and known
anti-aliasing techniques to make good use of the available output
sample grid (1,2).  On successive frames, new pictures are computed
for slightly shifted output sample grids, and the actual sample grid
of the display device is shifted to match, as shown in Figure 2
(dashed lines).  The shifting may be some combination of horizontal
and vertical shift.  Again, under suitable viewing conditions, the
eye sees a single image with greater apparent resolution than any of
the single displayed images.

      The amount of the shifting is not regulated by the invention.
According to economic and technical considerations, there may be just
two grids (displayed alternately), or the shift may be computed
dynamically and varied on each frame.  The invention requires that
the computation of the picture match the shifting of the display
grid.
Sample Hardware Implementation

      This section describes a possible implementation.  This is not
the only possible implementation.  Referring to Figure 3, all
information a...