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eksis  
#1 Posted : Wednesday, December 13, 2006 4:21:02 PM(UTC)
eksis

Rank: Member

Groups: Member
Joined: 11/11/2004(UTC)
Posts: 1

I am from Korea.

I am developing in ASP, and I want to get an Image from animated GIF Frames.
I used GIFReader Object.


The following code can extract images from the animated GIF "a.gif"

Code:
<%
Dim objBitmap
Set objBitmap = Server.CreateObject("MultiImage.GifReader")

objBitmap.OpenFile "a.gif"
objBitmap.IsLzwEnabled = true

Dim i
i = 0

for i=0 to objBitmap.Frames.count -1 
	objBitmap.Frames.Item(i).Bitmap.SaveToFile "a" &  i & ".gif"
next	

Set objBitmap = Nothing
%>


But, the extracted Images are not clear. some noises are appeared in the extracted images.

I don't Know the reason???

the sample image "a.gif" is attached..

Please, Answer me..

Thanks...

Edited by user Tuesday, December 18, 2007 7:51:28 PM(UTC)  | Reason: Not specified

eksis attached the following image(s):
a.gif
Andrew  
#2 Posted : Thursday, December 14, 2006 9:50:35 PM(UTC)
Andrew

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Groups: Member, Administration
Joined: 8/2/2003(UTC)
Posts: 866

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This GIF seems to be optimized when saved. It means that the software which created this movie compared two nearest frames and "subtracted" those parts of frame which are the same on both frames (it allows to reduce size). When the GIF viewer opens this file, it draws such frame directly on the previous one, without erasing it. As a result it looks correctly.

So if you do not want to have actual frame data, but just need to have frames as they are displayed in the GIF viewer, you need to blend each frame with the previous one.

In fact, it is a bit more difficult - you should take into account a property called DisposalMethod" (value specifying how the previous frame should be handled - erased, or just left as is - the next frame should be drawn on it as described above). Also, frame may have positioned on the previous frame - use the Left and Top properties.

Hope this helps.
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