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Drawing Engine
8.4 Input and Output Data Formats
8.4.1 Source and destination data
8.4.2 Texture colour formats
8.4.3 Framebuffer colour formats
There are two possible inputs and one possible output. One input is the
framebuffer and one input is the texture input or the pattern input. The output is
always the framebuffer.
Every drawing operation is internally rendered in 32 bit per pixel aRGB(8888). If
the input colour does not provide an alpha channel, the blue channel is taken as
alpha channel. This alpha can be substituted with any alpha (e.g. an external
constant) during the colourization step in the Drawing Engine.
•
8 bpp a(8): The colour format uses one byte per pixel alpha only. The
alpha channel is internally replicated on red, blue and green channel
and can be substituted by any colour during the colourization step
in the Drawing Engine.
•
8 bpp aCLUT(44): The colour format uses one byte per pixel. 4 bit
are used as an alpha value and 4 bit are used as an index into a colour
palette. This can be a real space saver if 16 colours are sufficient to
describe the image as the next bigger alpha format would be 2byte
(aRGB(4444)).
•
16 bpp RGB(565): The colour format uses 2 byte per pixel with 5 bit
for red, 5 bit for blue and 6 bit for green. The blue colour is taken as
the alpha channel during colour conversion. The alpha can be
substituted with any alpha during the colourization step in the
Drawing Engine.
•
16 bpp aRGB(4444): The colour format uses 2 byte per pixel with 4
bit for every channel.
•
16 bpp aRGB(1555): The colour format uses 2 byte per pixel. Every
colour channel has 5 bit and the topmost single bit is taken as an
alpha value. This can be used to hold image with a transparency
mask.
•
32 bpp aRGB(8888): The colour format uses 4 byte per pixel with 8
bit for every channel.
•
1 bit per pixel pattern: In pattern mode a one bit per pixel one
dimensional pattern can be used (32 bit register). The colour is then
switched between 2 colours that are stored inside the Drawing
Engine.
For the framebuffer following formats are possible. This is everything that the
texture input can use:
•
8 bpp a(8): The colour format uses one byte per pixel alpha only. The
alpha channel is internally replicated on red, blue and green channel
and can be substituted by any colour during the colourization step
in the Drawing Engine.
Preliminary User's Manual S19203EE1V3UM00
Chapter 8
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