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Change Opacity of Image in C#

, 27 May 2011 CPOL 0 1 12
A tip which enables you to change Opacity of Image in C#
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This is a simple tip/trick which enables you to change Opacity of Image using C# by using System.Drawing and System.Drawing.Imaging NameSpaces.
Take a look at how ChangeOpacity(Image img, float opacityvalue) method will enable you to change opacity of Image.
In this given code, System.Drawing Namespace is used to access Bitmap and Graphics classes whereas System.Drawing.Imaging Namespaces is used to access ColorMatrix and ImageAttributes.
ChangeOpacity method has two parameters including img for Image on which opacity will apply, and opacityvalue for set opacity level of form.

using System;
using System.Drawing;
using System.Drawing.Imaging;
namespace ImageUtils
    class ImageTransparency
        public static Bitmap ChangeOpacity(Image img, float opacityvalue)
            Bitmap bmp = new Bitmap(img.Width,img.Height); // Determining Width and Height of Source Image
            Graphics graphics = Graphics.FromImage(bmp);
            ColorMatrix colormatrix = new ColorMatrix();
            colormatrix.Matrix33 = opacityvalue;
            ImageAttributes imgAttribute = new ImageAttributes();
            imgAttribute.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            graphics.DrawImage(img, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imgAttribute);
            graphics.Dispose();   // Releasing all resource used by graphics 
            return bmp;

When you will use this method in your program to change opacity of an image in pictureBox control, you need to write code as given below:

float opacityvalue = float.Parse(txtopacityvalue.Text) / 100;
pictureBox1.Image = ImageUtils.ImageTransparency.ChangeOpacity(Image.FromFile("filename"),opacityvalue);  //calling ChangeOpacity Function 

To learn how to use the given code in your program:
Click here[^] to download source code.

[Edited-"Adding Reference Link"]
Reference Article: There-Image Opacity Using C#[^]


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

QuestionThanks, very good but ImageUtils namespace doesn't appear on C# Pin
Member 1049790721-Mar-14 14:04
professionalMember 1049790721-Mar-14 14:04 
QuestionThanks Pin
remoz22-Mar-13 2:31
memberremoz22-Mar-13 2:31 
QuestionTrying to modify the function for an auto fade in effect. Pin
Zerophase6-Feb-13 15:20
memberZerophase6-Feb-13 15:20 
QuestionIn web form i am unable to pass the image parameter how can i do this Pin
sreedharmasula5-Jan-13 22:46
membersreedharmasula5-Jan-13 22:46 
GeneralThanks Ravi! Not exactly for the tip, but for the idea of st... Pin
Manfred R. Bihy28-May-11 13:06
mvpManfred R. Bihy28-May-11 13:06 
GeneralRe: Thanks :) Pin
RaviRanjankr28-May-11 19:42
mvpRaviRanjankr28-May-11 19:42 
GeneralInteresting solution! Typically I tend to use CCS/jQuery cli... Pin
DrABELL27-May-11 16:02
memberDrABELL27-May-11 16:02 
GeneralRe: Thank you DrABELL :) Pin
RaviRanjankr27-May-11 19:59
mvpRaviRanjankr27-May-11 19:59 
GeneralIsn't it similar to this article: <a href="http://howtoideas... Pin
Tarun.K.S25-May-11 22:47
memberTarun.K.S25-May-11 22:47 
GeneralRe: Yeah! its very similar to the refer article infact I've just... Pin
RaviRanjankr25-May-11 23:31
mvpRaviRanjankr25-May-11 23:31 
Yeah! its very similar to the refer article infact I've just made a global function which can be simply or easily used by taking appropriate parameter. Honestly I've taking steps mentioned in Given article. Smile | :)

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