performance issue when the interpolation mode (GDI+)

  • Thread starter Thread starter Ravi
  • Start date Start date
R

Ravi

Hi,

I have a performance issue when the interpolation mode is set to
Bicubic. The image (of size 1 MB) is zoomed 10 times. When the image
is viewed using scroll bars in a picturebox control, there is a choppy
effect, where as, when the interpolation mode is set to
HiQualityBicubic (or for any other mode, apart from Bicubic), this
effect is not to be seen.

Any ideas...
Thanks in Advance
 
Different interpolation modes = different math.

Different math = different memory/register/cpu behavior while calculating
the interpolation.

Different behavior = different performance.

That said, I sure as heck haven't seen the DrawImage interpolation code
(although I'd like to, as I don't understand why the "Low" setting doesn't
just zoom up the individual pixels), and so I can't comment on what actual
math is taking place for each mode. If you really require the quality given
by "Bicubic", though, and you've proven to your satisfaction that the
performance issue really is with the interpolation mode, then I doubt
there's anything you can do about it.

It does seem strange, however, that "HiQualityBicubic" would have higher
performance than simple "Bicubic". Maybe someone from the GDI team is
listening and can comment?
 
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