Solved

DPI Conversion

Posted on 2009-07-09
2
2,428 Views
Last Modified: 2013-12-03
I have a scanned image of a document that is 366dpi

width: 3424
height: 5606

I want to convert the DPI to 300.  I have used the code attached to convert it successfully to 300.  However the physical size of the image has increased and is unacceptable for our needs.  I am looking for a way to change the dpi of a tiff/bitmap and keep the original physical size of the image.  Any ideas would be great.  I am working in C# .net.


Bitmap pages = null;
System.IO.FileStream myStream = new FileStream(strImageFile, System.IO.FileMode.Open);
 pages = (Bitmap)Image.FromStream(myStream);
 pages.SetResolution(newDPI, newDPI);
  pages.Save(outFile, info, ep);

Open in new window

0
Comment
Question by:alpacaman
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 15

Accepted Solution

by:
oobayly earned 125 total points
ID: 24823579
You have to work out the physical size of the original first. Then you can create a duplicate of the original with a calculated pixel size based on your new resolution
      // Determine the Physical size of the original
      SizeF physical = new SizeF(
        pages.Width / pages.HorizontalResolution,
        pages.Height / pages.VerticalResolution);
 
      // Determine the required pixel size of the new image
      float newResolution = 300;
      SizeF newPixelSize = new SizeF(
        physical.Width * newResolution,
        physical.Height * newResolution);
 
      Bitmap newImage = new Bitmap(pages, Size.Round(newPixelSize));
      newImage.SetResolution(newResolution, newResolution);

Open in new window

0
 
LVL 1

Author Closing Comment

by:alpacaman
ID: 31601668
thanks for the snippet, helped a lot
0

Featured Post

The Orion Papers

Are you interested in becoming an AWS Certified Solutions Architect?

Discover a new interactive way of training for the exam.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Australian government abolished Visa 457 earlier this April and this article describes how this decision might affect Australian IT scene and IT experts.
CTAs encourage people to do something specific to show interest in your company, product or service. Keep reading to learn why CTAs should always be thought of as extremely important, albeit small, sections of websites.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
Any person in technology especially those working for big companies should at least know about the basics of web accessibility. Believe it or not there are even laws in place that require businesses to provide such means for the disabled and aging p…

724 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question