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Resize an image in C#

This is a snippet for resizing an image based on a percentage. If the user wants the image to be 75% of the original then pass the number 75

Submitted By: PsychoCoder

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Views: 2,548

Language: C#

Last Modified: May 25, 2008

Instructions: Need references to System.Drawing, System.Drawing.Drawing2D, System.Drawing.Imaging Namespaces

Snippet

//Namespace Reference
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
/// <summary>
/// method for resizing an image
/// </summary>
/// <param name="img">the image to resize</param>
/// <param name="percentage">Percentage of change (i.e for 105% of the original provide 105)</param>
/// <returns></returns>
public Image Resize(Image img, int percentage)
{
//get the height and width of the image
int originalW = img.Width;
int originalH = img.Height;
//get the new size based on the percentage change
int resizedW = (int)(originalW * percentage);
int resizedH = (int)(originalH * percentage);
//create a new Bitmap the size of the new image
Bitmap bmp = new Bitmap(resizedW, resizedH);
//create a new graphic from the Bitmap
Graphics graphic = Graphics.FromImage((Image)bmp);
graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
//draw the newly resized image
graphic.DrawImage(img, 0, 0, resizedW, resizedH);
//dispose and free up the resources
graphic.Dispose();
//return the image
return (Image)bmp;
}

Copy & Paste

//Namespace Reference
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

/// <summary>
/// method for resizing an image
/// </summary>
/// <param name="img">the image to resize</param>
/// <param name="percentage">Percentage of change (i.e for 105% of the original provide 105)</param>
/// <returns></returns>
public Image Resize(Image img, int percentage)
{
    //get the height and width of the image
    int originalW = img.Width;
    int originalH = img.Height;

//get the new size based on the percentage change
    int resizedW = (int)(originalW * percentage);
    int resizedH = (int)(originalH * percentage);

//create a new Bitmap the size of the new image
    Bitmap bmp = new Bitmap(resizedW, resizedH);
    //create a new graphic from the Bitmap
    Graphics graphic = Graphics.FromImage((Image)bmp);
    graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
    //draw the newly resized image
    graphic.DrawImage(img, 0, 0, resizedW, resizedH);
    //dispose and free up the resources
    graphic.Dispose();
    //return the image
    return (Image)bmp;
}

Comments
thomerow 2008-11-18 03:45:12
If you only want to downscale images use InterpolationMode.HighQualityLinear. It is slightly faster than bicubic resizing and makes no visible difference.