How to crop part of gif image?

Question

Hi every one,

i wrote some code to crop large image to small one.

Everything is OK but when i tried GIF images i get the following exception

"A Graphics object cannot be created from an image that has an indexed pixel format."

I'm using Graphics class to do this

Graphics gfx = Graphics.FromImage(croppedBitmap)

thank you.

Answer 1

codeproject - Resizing a Photographic image with GDI+ for .NET

Answer 2

The pixels of GIF images are not RGB values, they are indexes of a color table array stored in the header of the file. Graphic objects only support non-indexed pixel format. If you want to use the Graphic object, you must convert your image into a non-indexed pixel format.

This is exactly what this guy did: http://www.codeproject.com/KB/cs/WriteTextToGif.aspx?display=PrintAll