[I sent this out a few days ago, but replied to the wrong address so I
don't believe it went through - sending again...jim]
The Bilinear filtering algorithm is a well known algorithm that has a
very specific definition which we follow. If we automatically applied
multiple steps based on the scaling factor then we would violate that
definition and have to call it something else.
On a more practical note, if someone has determined that the caveats of
the bilinear algorithm are sufficient for their needs and we did perform
multiple steps instead of one step then we would reduce performance
which that particular developer might not appreciate.
On another practical note, hardware accelerators do not perform
multi-step scaling so we wouldn't be able to fire the request off to the
video card and get hardware accelerated scaling (nearly free) if we
instituted such a policy behind the scenes.
If we did provide that mechanism automatically then it would have to be
under a different name so that the developer could buy into the specific
tradeoffs that it provides (better quality for >2x downscaling at the
expense of about 7x performance).
In the meantime, we publish blogs like the one you point to in order to
educate our programmers about the definitions of the graphical terms and
processes that our APIs allow them to access and how to use those well
defined industry standard mechanisms to achieve their needs...
...jim
[EMAIL PROTECTED] wrote:
There is an article that mentions that one can improve the look of downscaling
using BILINEAR by downscaling multiple times (each time by half):
http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
The paragraph in question reads: "To combat this issue, you can use a multi-step
approach when downscaling by more than two times; this helps prevent the information loss
issue and produces a much higher quality result that is visually quite close to that
produced by Image.SCALE_AREA_AVERAGING"
My question is, why doesn't Java do this automatically under the hood? If I
request BILINEAR or BICUBIC downscaling for a factor greater than two, why
doesn't Java either do multistep scaling on my behalf or why doesn't the Java2D
team add a new hint (to maintain backwards compatibility) which will tell
Java2D to apply these filters using the multi-step method? I would much rather
have this supported by the JDK than having people reinvent the wheel over and
over.
Thank you,
Gili
[Message sent by forum member 'cowwoc' (cowwoc)]
http://forums.java.net/jive/thread.jspa?messageID=227363
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