Changing image opacity, Resize image, crop image and gray scale image : Image « 2D Graphics « C# / C Sharp

Changing image opacity, Resize image, crop image and gray scale image


using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web;
using System.Drawing.Imaging;
using System.IO;
using System.Windows.Forms;  

namespace Mynx
    class ImageUtilities
        /// <summary>  
        /// method for changing the opacity of an image  
        /// </summary>  
        /// <param name="image">image to set opacity on</param>  
        /// <param name="opacity">percentage of opacity</param>  
        /// <returns></returns>  
        public Image SetImageOpacity(Image image, float opacity)
                //create a Bitmap the size of the image provided  
                Bitmap bmp = new Bitmap(image.Width, image.Height);

                //create a graphics object from the image  
                Graphics gfx = Graphics.FromImage(bmp);

                //create a color matrix object  
                ColorMatrix matrix = new ColorMatrix();

                //set the opacity  
                matrix.Matrix33 = opacity;

                //create image attributes  
                ImageAttributes attributes = new ImageAttributes();

                //set the color(opacity) of the image  
                attributes.SetColorMatrix(matrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);

                //now draw the image  
                gfx.DrawImage(image, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, attributes);
                return bmp;
            catch (Exception ex)
                return null;

        public static Image Resize(Image imgToResize, Size size)
            int sourceWidth = imgToResize.Width;
            int sourceHeight = imgToResize.Height;

            float nPercent = 0;
            float nPercentW = 0;
            float nPercentH = 0;

            nPercentW = ((float)size.Width / (float)sourceWidth);
            nPercentH = ((float)size.Height / (float)sourceHeight);

            if (nPercentH < nPercentW)
                nPercent = nPercentH;
                nPercent = nPercentW;

            int destWidth = (int)(sourceWidth * nPercent);
            int destHeight = (int)(sourceHeight * nPercent);

            Bitmap b = new Bitmap(destWidth, destHeight);
            Graphics g = Graphics.FromImage((Image)b);
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;

            g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);

            return (Image)b;

        public static Image Crop(Image img, Rectangle cropArea)
            Bitmap bmpImage = new Bitmap(img);
            Bitmap bmpCrop = bmpImage.Clone(cropArea, bmpImage.PixelFormat);
            return (Image)(bmpCrop);

        public static Bitmap GrayscaleConvert(Bitmap original)
            //create a blank bitmap the same size as original
            Bitmap newBitmap = new Bitmap(original.Width, original.Height);

            //get a graphics object from the new image
            Graphics g = Graphics.FromImage(newBitmap);

            //create the grayscale ColorMatrix
            ColorMatrix colorMatrix = new ColorMatrix(new float[][] 
             new float[] {.3f, .3f, .3f, 0, 0},
             new float[] {.59f, .59f, .59f, 0, 0},
             new float[] {.11f, .11f, .11f, 0, 0},
             new float[] {0, 0, 0, 1, 0},
             new float[] {0, 0, 0, 0, 1}

            //create some image attributes
            ImageAttributes attributes = new ImageAttributes();

            //set the color matrix attribute

            //draw the original image on the new image
            //using the grayscale color matrix
            g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height), 0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes);

            //dispose the Graphics object
            return newBitmap;


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