Hi Michael,
All BufferedImage types should be equally "manageable" as we make a copy
in VRAM in whatever format is necessary for display regardless of the
source image type. If the graphics card wants PRE images then the
accelerated copy will be PRE, or not as the case may be.
Working on premultiplied data is usually considered a win for the
blending operations since it avoids the need to have to multiply the
color components by the alpha. Unfortunately, the picture isn't that
simple since, while it avoids the "need" to do the multiply, the various
other math operations that the blending requires can sometimes absorb
the alpha multiplier into other operations and the effect ends up being
minimal in practice. It would be better to benchmark the specific
operations you are doing to see if there is any performance advantage.
The most straightforward way to turn an ARGB image into an ARGB_PRE
image would be to render it into a different image. You might be able
to use the constructor that takes a ColorModel and a Raster to do the
job for you, but keep in mind that the Raster for the original image
would be altered forever. It may save you the allocation of a new
buffer, but I'm not sure that the implicit coercion of data that happens
in that constructor (which uses coerceData in an arguably appropriate
way) is as fast as rendering from one image to the other. Benchmark to
see if it makes a difference one way or the other...
...jim
[EMAIL PROTECTED] wrote:
Jim, thanks very much for your reply.
I'm swimming through these issues right now, trying to avoid instances of
coerceData and figure out where to be using ARGB vs ARGB_PRE, and have the
following concerns. Any thoughts on these, or on further resources to look at,
would be most appreciated.
Is there a preferred way to get premultiplied data from an ARGB image (I'm
currently thinking create a new ARGB_PRE and call drawImage())?
What effect does using the different BufferedImage type have on graphics
performance, e.g. managed vs. unmanaged images? Any reason a PRE image can't
be accelerated? Any reason to prefer one to the other for drawing to the
screen?
Again, thanks,
michael
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