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Monday, February 18, 2008

C# : indexed pixel problem

Here I will mention the solve for a common problem happens when you try to create Graphic object from Bitmap images as in the next two lines..yes, it would fire an exception if your bitmap was indexed pixel .

Bitmap tmp = new Bitmap("Fci-h.jpg");
Graphics grPhoto = Graphics.FromImage(tmp);

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

To pass this exception you will need to add some additional lines of code . Just create an image with the same size like the original image (Fci-h.jpg) then draw the original image onto the new Graphics object .

Here is an Example :

Bitmap bm = (Bitmap) System.Drawing.Image.FromFile("Fci-h.jpg",true);
Bitmap tmp=new Bitmap (bm.Width ,bm.Height );
Graphics grPhoto = Graphics.FromImage(tmp);
grPhoto.DrawImage(bm, new Rectangle(0, 0, tmp.Width , tmp.Height ), 0, 0, tmp.Width , tmp.Height , GraphicsUnit.Pixel);


Juice said...

Thanks for this.

Anonymous said...

Worked perfectly! Thanks. Probably not very memory efficent but I'm just drawing a simple graph on a picture.

WebDevHobo said...

Awesome, this helped me out with PNG images. Thanks, the resulting filesize of my images is now 5 times smaller.

Anonymous said...


Anonymous said...

Very good!