SH7205 Datasheet, PDF (1465/1904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Figure 25.34: Source pixels,
original image
Section 26 2D Graphics Engine (2DG)
Figure 25.34: Destination pixels (1)
Through the bilinear method, reduction
by 1/2 in the horizontal direction only
Starting phase (H1PHS_DCML) = H'000
Figure 25.34: Destination pixels (2)
Through the bilinear method, reduction
by 1/2 in the horizontal direction only
Starting phase (H1PHS_DCML) = H'800
The image consists of colored vertical
bars, with the color omitted for one dot,
two dots, and three dots between bars
for the upper third, central third, and
lower third, respectively.
Image size: 130 × 60 pixels
Since the contribution of the colored
pixels is cut from the upper third, where
the source image had colored bars
separated by one dot, the corresponding
area is white (the proportion of the color
value to the white value is 1:0).
In the case of the upper third, where the
source image had colored bars separated
by one dot, since the color value and
white value are blended by averaging,
the color value is taken into account even
though the lines disappear (the proportion
of the color value to the white value is 1:1).
Figure 26.35 Examples of the Results when Settings for Starting Phase in Resizing for
Reduction (Magnification by Half)
As shown in figure 26.35, when resizing for reduction of the upper third with one dot omitted is
obtained by the bilinear method with a starting phase of H'000, the proportion between the color
values of the white and colored pixels becomes 1:0, so the color value of the colored pixels is
simply eliminated. When the starting phase is H'800, the proportion between the color values of
the white and colored pixels becomes 1:1 and, since the color values of the white and colored
pixels are blended in equal portions, the color of the colored pixels is reproduced although the
vertical lines disappear.
Since pixels are not omitted in the case of resizing for enlargement, the kind of strong effect seen
in the case of resizing for reduction is absent. However, the setting for starting phase can still be
used to control the proportions of the two source pixels used as reference in resizing for
enlargement (through the bilinear method).
(5) Partial Resizing
When modifying a part of the area on a resized source plane, a partial extraction should be
performed on the source area before resizing instead of after. The reason is that the correct
boundaries can be maintained by partially extracting the source area before resizing and by pasting
the area to the part of the area on the resized plane. An example of this is shown in figure 26.36.
Partial resizing, however, cannot be performed when color gradation processing is selected.
The partially modified area (the updated area in figure 26.36) is defined as follows:
Vertical offset = Va, horizontal offset = Ha, height = Vb, width = Hb
Rev. 1.00 Mar. 25, 2008 Page 1433 of 1868
REJ09B0372-0100