SoFunction
Updated on 2025-03-06

A brief discussion on image processing (reading, saving and accessing pixels) in Visual C#


using System;
using ;
using ;
using ;
using ;
using ;
using ;
namespace ImageElf
{
    class GrayBitmapData
    {
public byte[,] Data;//Save the pixel matrix
public int Width;//The width of the image
public int Height;//The height of the image
        public GrayBitmapData()
        {
            = 0;
            = 0;
            = null;
        }
        public GrayBitmapData(Bitmap bmp)
        {
            BitmapData bmpData = (new Rectangle(0, 0, , ), , PixelFormat.Format24bppRgb);
            = ;
            = ;
            Data = new byte[Height, Width];
            unsafe
            {
                byte* ptr = (byte*)bmpData.();
                for (int i = 0; i < Height; i++)
                {
                    for (int j = 0; j < Width; j++)
                    {
//Convert 24-bit RGB color diagram to grayscale diagram
                        int temp = (int)(0.114 * (*ptr++)) + (int)(0.587 * (*ptr++))+(int)(0.299 * (*ptr++));
                        Data[i, j] = (byte)temp;
                    }
ptr += - Width * 3;//Pointer plus fill blank space
                }
            }
            (bmpData);
        }
        public GrayBitmapData(string path)
            : this(new Bitmap(path))
        {
        }
        public Bitmap ToBitmap()
        {
            Bitmap bmp=new Bitmap(Width,Height,PixelFormat.Format24bppRgb);
            BitmapData bmpData=(new Rectangle(0,0,Width,Height),,PixelFormat.Format24bppRgb);
            unsafe
            {
                byte* ptr=(byte*)bmpData.();
                for(int i=0;i<Height;i++)
                {
                    for(int j=0;j<Width;j++)
                    {
                        *(ptr++)=Data[i,j];
                        *(ptr++)=Data[i,j];
                        *(ptr++)=Data[i,j];
                    }
                    ptr+=-Width*3;
                }
            }
            (bmpData);
            return bmp;
        }
        public void ShowImage(PictureBox pbx)
        {
            Bitmap b = ();
            = b;
            //();
        }
        public void SaveImage(string path)
        {
            Bitmap b=ToBitmap();
            (path);
            //();
        }
//Mean filtering
        public void AverageFilter(int windowSize)
        {
            if (windowSize % 2 == 0)
            {
                return;
            }
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    int sum = 0;
                    for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++)
                    {
                        for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++)
                        {
                            int a = i + g, b = j + k;
                            if (a < 0) a = 0;
                            if (a > Height - 1) a = Height - 1;
                            if (b < 0) b = 0;
                            if (b > Width - 1) b = Width - 1;
                            sum += Data[a, b];
                        }
                    }
                    Data[i,j]=(byte)(sum/(windowSize*windowSize));
                }
            }
        }
//Medium filtering
        public void MidFilter(int windowSize)
        {
            if (windowSize % 2 == 0)
            {
                return;
            }
            int[] temp = new int[windowSize * windowSize];
            byte[,] newdata = new byte[Height, Width];
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    int n = 0;
                    for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++)
                    {
                        for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++)
                        {
                            int a = i + g, b = j + k;
                            if (a < 0) a = 0;
                            if (a > Height - 1) a = Height - 1;
                            if (b < 0) b = 0;
                            if (b > Width - 1) b = Width - 1;
                            temp[n++]= Data[a, b];
                        }
                    }
                    newdata[i, j] = GetMidValue(temp,windowSize*windowSize);
                }
            }
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    Data[i, j] = newdata[i, j];
                }
            }
        }
//Get the median value of a vector
        private byte GetMidValue(int[] t, int length)
        {
            int temp = 0;
            for (int i = 0; i < length - 2; i++)
            {
                for (int j = i + 1; j < length - 1; j++)
                {
                    if (t[i] > t[j])
                    {
                        temp = t[i];
                        t[i] = t[j];
                        t[j] = temp;
                    }
                }
            }
            return (byte)t[(length - 1) / 2];
        }
//A new filtering method is brighter and darker
        public void NewFilter(int windowSize)
        {
            if (windowSize % 2 == 0)
            {
                return;
            }
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    int sum = 0;
                    for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++)
                    {
                        for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++)
                        {
                            int a = i + g, b = j + k;
                            if (a < 0) a = 0;
                            if (a > Height - 1) a = Height - 1;
                            if (b < 0) b = 0;
                            if (b > Width - 1) b = Width - 1;
                            sum += Data[a, b];
                        }
                    }
                    double avg = (sum+0.0) / (windowSize * windowSize);
                    if (avg / 255 < 0.5)
                    {
                        Data[i, j] = (byte)(2 * avg / 255 * Data[i, j]);
                    }
                    else
                    {
                        Data[i,j]=(byte)((1-2*(1-avg/255.0)*(1-Data[i,j]/255.0))*255);
                    }
                }
            }
        }
//Histogram equalization
        public void HistEqual()
        {
            double[] num = new double[256] ;
            for(int i=0;i<256;i++) num[i]=0;
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    num[Data[i, j]]++;
                }
            }
            double[] newGray = new double[256];
            double n = 0;
            for (int i = 0; i < 256; i++)
            {
                n += num[i];
                newGray[i] = n * 255 / (Height * Width);
            }
            for (int i = 0; i < Height; i++)
            {
                for (int j = 0; j < Width; j++)
                {
                    Data[i,j]=(byte)newGray[Data[i,j]];
                }
            }
        }
}
}