by sweisfeld via Shawn Weisfeld [MVP] on 6/28/2009 6:52:00 PM
I wrote this for an INETA project that I have been working on, but thought it would be great to share with everyone. We had a need to take an image and change its size. Below is an implementation of a Resize Extension Method on the .NET Image object.
I borrowed some ideas from this post by Mark McDonnell (http://weblogs.asp.net/markmcdonnell/archive/2008/03/09/resize-image-before-uploading-to-server.aspx)
1: using System;
2: using System.Collections.Generic;
3: using System.Linq;
4: using System.Text;
5: using System.Drawing;
6: using System.Drawing.Drawing2D;
7:
8: namespace Demo
9: {
10: public enum ResizeMode
11: {
12: Width,
13: Height,
14: Bigger
15: }
16:
17: public static class ImageHelper
18: {
19: public static Image Resize(this Image source, int size, ResizeMode mode)
20: {
21: //Convert the source image into a bitmap so we can work with it
22: Bitmap originalBMP = new Bitmap(source);
23: Image result;
24:
25: // Calculate the new image dimensions
26: int origWidth = originalBMP.Width;
27: int origHeight = originalBMP.Height;
28: int newWidth = 0;
29: int newHeight = 0;
30:
31: //If the size mode is set to bigger then find the widest side
32: if (mode == ResizeMode.Bigger)
33: {
34: if (origHeight > origWidth)
35: mode = ResizeMode.Height;
36: else
37: mode = ResizeMode.Width;
38: }
39:
40: //keeping the aspect ratio constant, calculate the new size
41: if (mode == ResizeMode.Width)
42: {
43: newWidth = size;
44: newHeight = (int)(size / ((double)origWidth / (double)origHeight));
45: }
46: else
47: {
48: newHeight = size;
49: newWidth = (int)(size / ((double)origHeight / (double)origWidth));
50: }
51:
52:
53: // Create a new bitmap which will hold the previous resized bitmap
54: Bitmap newBMP = new Bitmap(originalBMP, newWidth, newHeight);
55:
56: // Create a graphic based on the new bitmap
57: using (Graphics oGraphics = Graphics.FromImage(newBMP))
58: {
59: // Set the properties for the new graphic file
60: oGraphics.SmoothingMode = SmoothingMode.AntiAlias;
61: oGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
62:
63: // Draw the new graphic based on the resized bitmap
64: oGraphics.DrawImage(originalBMP, 0, 0, newWidth, newHeight);
65:
66: // Save the new graphic file to the server
67: result = newBMP.Clone() as Image;
68:
69: // Once finished with the bitmap objects, we deallocate them.
70: originalBMP.Dispose();
71: newBMP.Dispose();
72: oGraphics.Dispose();
73: }
74:
75: return result;
76: }
77: }
78: }
Using an extension method makes it really easy to use the new “resize” functionality:
1: Image img = Image.FromFile("img.jpg");
2: Image resized = img.Resize(100, ResizeMode.Bigger);
3: resized.Save("resized.jpg");
So we went from a source size of 2304x1728 and 782 KB
to 100x75 and 23.3 KB
Now you to can shrink the size of your memories. :)
Original Post: Extension Method to Resize an Image
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