Re: Speeding up Bitmaps Loading

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Perlom (perlom_at_no_spam_hotmail.com)
Date: 06/18/04 

Date: Fri, 18 Jun 2004 11:25:25 -0400

Thanks Phillip for the Info. Can you direct me to where I can find few
samples about the method you suggested, or to which forum I should ask?

kind regards.

"Philip Taylor [ATI]" <ptaylor@online.newsgroup-poster.ati.com> wrote in
message news:OA7uIZIVEHA.1048@tk2msftngp13.phx.gbl...
> load it as a DirectX texture, and access it that way, since GDI based
access
> are usually slower than DX accesses.
>
> this requires you to understand the texture format to such a level of
detail
> you dont have to depend on GDIs format conversion, which is usually the
slow
> part.
>
> if its really just the file access thats the bottleneck, than DX cant help
> you much and this forum isnt the right place to ask.
>
> "Perlom" <perlom@no_spam_hotmail.com> wrote in message
> news:e0sc$4HVEHA.1472@TK2MSFTNGP09.phx.gbl...
> > I am trying to load a sequence of large bitmaps (720*486) and then loop
> thru
> > each pixel and convert its color space form RGB to YCbCr which is used
in
> TV
> > broadcasting. I'm using VB.NET. Unfortunately, the overall process came
> up
> > to be real slow specially when running this on 300 frames (around 3
> > minutes). The steps are:
> >
> > - Loop thru al files to load each bitmap:
> > Dim mBitmap as Bitmap = Bitmap.FromFile(FileName(i))
> >
> > - Loop thru each pixel, get the color, and apply mathematical
conversion
> > For J = 0 to mBitmapHeight
> > For K = 0 to mBitmapWidth
> > mColor = mBitmap.GetPixel(K,J)
> > Y = (Some math function involving R,G,B Values)
> > Cb= (Some math function involving R,G,B Values)
> > Cr= (Some math function involving R,G,B Values)
> > mFile.Write( values)
> > Next
> > Next
> >
> > After doing some analysis, I found that the bottle nock is loading the
> > Bitmap step. I am wondering if there any faster way to load a Bitmap. I
> > read on the MSDN site about Cashed Bitmaps, but I wasn't able to find an
> > example. Anybody has a suggestion? Thanks in advance.
> >
> > Kind Regards.
> >
> >
>
>

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