Re: Is this a known bug with the Bitmap class??

From: Chris R. Timmons (crtimmons_at_X_NOSPAM_Xcrtimmonsinc.com)
Date: 07/08/04 

Date: Wed, 07 Jul 2004 22:18:03 -0700

"TCR" <thereagans97@verizon.net> wrote in
news:Pv2Hc.39137$MT5.13387@nwrdny01.gnilink.net:

> Hi,
> I posted this earlier and got a suggestion that didn't pan
> out. I am
> trying to determine if there is a known bug related to the
> resolution value returned when opening a .jpg file by passing
> the file path to the bitmap class constructor or by using the
> Image.FromImage() static function to return a bitmap object. I
> have tried to open a jpeg file to convert its resolution to a
> lower value but it doesn't return the proper resolution value
> when loading the initial image.. I know the images are 300 X
> 300 dpi but it reports them as 72 X 72 dpi.

Troy,

The code below works for me. Note that if the image file doesn't
contain any resolution data, then the resolution of the
Bitmap/Graphics image defaults to the resolution of the video screen
(per Charles Petzold in "Programming Windows with C#").

You may want to ask this question again in the
microsoft.public.dotnet.framework.drawing group. There may be some
dotnet image experts there who don't frequent this group. 

-- 
Hope this helps.
Chris.
-------------
C.R. Timmons Consulting, Inc.
http://www.crtimmonsinc.com/
---------------------------------------------------
using System;
using System.Drawing;
namespace Example
{
  public class ExampleClass
  {
    public static int Main(string[] args)
    {
      // An image known to have 96 dpi.
      string imagePath = @"C:\A_96_dpi_image.jpg";
      ///////////
      // Bitmap
      ///////////
      using (Bitmap b = new Bitmap(imagePath))
      {
        Console.WriteLine("Bitmap b:");
        Console.WriteLine("  b.HorizontalResolution = {0}", 
          b.HorizontalResolution);
        Console.WriteLine("  b.VerticalResolution = {0}", 
          b.VerticalResolution);
        Console.WriteLine("");
      }
      ///////////
      // Image and Graphics
      ///////////
      Image i = Image.FromFile(imagePath);
      using (Graphics g = Graphics.FromImage(i))
      {
        Console.WriteLine("Graphics g:");
        Console.WriteLine("  g.DpiX = {0}", g.DpiX);
        Console.WriteLine("  g.DpiY = {0}", g.DpiY);
      }
      return 0;
    }
  }
}

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