Resizing gif down. Quality suffers RSS

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  engwar

  Member

  7 Points

  96 Posts

  Resizing gif down. Quality suffers

  Dec 28, 2005 09:34 AM|engwar|LINK

  I'm writing some file upload code for users on my website. If the image is too large I want to resize it smaller to a thumbnail size. It's working fine for jpegs but the thumbnails of the gifs look pretty bad.

  I assume it's something to do with the color palette. I don't know a whole lot about graphics programming. Can anyone assist?

  Here's the code I'm currently using.

  System.Drawing.Image img2 = new Bitmap(iImgWidthNew, iImgHeightNew, PixelFormat.Format24bppRgb);
  Graphics oGraphic = Graphics.FromImage(img2);
  oGraphic.CompositingQuality = CompositingQuality.HighQuality ;
  oGraphic.SmoothingMode = SmoothingMode.HighQuality ;
  oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic ;
  Rectangle oRectangle = new Rectangle(0, 0, iImgWidthNew, iImgHeightNew);
  oGraphic.DrawImage(objImage, oRectangle);

  I get the same poor results if I don't pass a PixelFormat in the first line.

  I can see having quality suffer if I INCREASED the size of the image but don't see why it suffers when I DECREASE it.

  Would I have better results if I convert it to a .jpg and save it that way? Most images uploaded will be photos but there might be some illustrations uploaded as gifs.

  Will I have a similar problem with png files?

  Thanks for helping this newbie.

• • Reply
  webbes

  Member

  11 Points

  415 Posts

  Betreft: Resizing gif down. Quality suffers

  Jan 06, 2006 03:21 AM|webbes|LINK

  Howdie,

  Have a look over here: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/colorquant.asp

  or here: http://forums.asp.net/1064190/ShowPost.aspx

  Cheers,

  Wes

  Listen carefully, I will say this only once...