Re: Need fast Bitmap Compare Method

Thanks for the reply adam and peter. I have looked at
the XOR example and so
far seems to be exactly what I need. I will try it
tonight.

 Adam I agree that using unsafe code would speed it
up. A few days ago I
tried this as well and did find improvements, but
still went too slow.

 My code is doing two 'for' loops, one 'for' loop for
going across the
screen, and one 'for' loop going down the screen
scanning a 128x96 region.
The moment it found something that didn't match it
would clone that region.
 Hopefully that XOR will work better than what im
using.


Have a great afternoon.

Steve

-----Original Message-----
From: Discussion relating to the specifics of the C#
and Managed C++
languages [mailto:DOTNET-CX@xxxxxxxxxxxxxxxxxxx] On
Behalf Of Peter Ritchie
Sent: Monday, September 19, 2005 8:31 AM
To: DOTNET-CX@xxxxxxxxxxxxxxxxxxx
Subject: Re: [DOTNET-CX] Need fast Bitmap Compare
Method

I would suggest using XOR.  An example for C#:
http://www.codersource.net/csharp_image_processing_xor.aspx

If that's still too slow, you could use pinvoke and
BitBlt() (and
SelectObject(), CreateCompabtibleBitmap(), etc.) with
the SRCINVERT
operator.  I don't have any sample code though.

http://www.peterRitchie.com/

On Mon, 19 Sep 2005 06:40:44 -0700, Steve Welborn
<swelborn2001@xxxxxxxxx>
wrote:

>I am hoping someone couldpresent a prebuilt class or
code that shows how
to compare 2 bitmaps and returnonly the changed
area's. The one I
currently built is just too slow. Slow as init will
actually scan image 2
and compare it to Image 1 in like 2 seconds.veryvery
slow.
>
>
>
>
>
>
>
>My solution is in C#, whichis what my app is in. C++
would be faster,
just as long as I can dllimport itin and the return be
compatible.
>
>
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>
>
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>
>Any suggestions would beappreciated.

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