題目:
Reducing the Number of Intensity Levels in an Image:
Write a computer program capable of reducing the number of intensity levels in a image from 256 to 4, in integer powers of 2. The desired number of intensity levels needs to be a variable input to your program.
但我寫出來的程式,沒有達到題目的要求
我的程式碼:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MiM_iVision; // using namespace of MiM Image Library that can use their Function

namespace
{
public partial class Form1 : Form

{
    public IntPtr GrayImage = iImage.CreateGrayiImage();
    public IntPtr hbitmap;
    E_iVision_ERRORS err = E_iVision_ERRORS.E_NULL;
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void Form1_FormClosed(object sender, FormClosedEventArgs e)
    {
        iImage.DestroyiImage(GrayImage);  // Release the image struction before shut down the Application

    }

    private void button1_Click(object sender, EventArgs e)
    {
       
        openFileDialog1.Filter = "BMP file |* .bmp";
        string filepath;                                       // Declare a string type of variable
        if (openFileDialog1.ShowDialog() == DialogResult.OK)
        {
            filepath = openFileDialog1.FileName;
            err = iImage.iReadImage(GrayImage, filepath);
            if (err == E_iVision_ERRORS.E_OK)
            {
                hbitmap = iImage.iGetBitmapAddress(GrayImage); //Get GrayImage's hbitmap
                if (pictureBox1.Image != null)                 //If there is an image on the Picturebox   
                    pictureBox1.Image.Dispose();               //clear Picturebox image                  
                pictureBox1.Image = System.Drawing.Image.FromHbitmap(hbitmap);
                pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;  //Set PictureBox size mode
                pictureBox1.Refresh();                         // refresh to update the Picturebox
            }
            else
                MessageBox.Show(err.ToString(), "Error");
        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        int Width = iImage.GetWidth(GrayImage);        // Get image width
        int Height = iImage.GetHeight(GrayImage);      // Get image height
        int Threshold = Convert.ToInt32(tb_Threshold.Text);
        IntPtr GrayImage1 = iImage.CreateGrayiImage(); ;
        iImage.iImageResize(GrayImage1, Width, Height);
        iImage.iImageCopy(GrayImage1, GrayImage);
        byte[,] Graymatrix = new byte[Height, Width];
        err = iImage.iPointerFromiImage(GrayImage1, ref Graymatrix[0, 0], Width, Height);
        if (err != E_iVision_ERRORS.E_OK)              // Check the status from functions
        {
            MessageBox.Show(err.ToString(), "ERROR");  // This will open a MessagBox for warning.
            return;                                    // End "Binary Threshold Event Function" 
        }
        // start sliding the matrix
        for (int i = 0; i < Height; i++)               // i index for cols ( 0~Hight-1)(Because that matrix index is start from 0)
        {
            for (int j = 0; j < Width; j++)            // j index for rows ( 0~Width-1)
            {
                if (Graymatrix[i, j] < Threshold)      // Compare if the image intensity of each pixel smaller than threshold
                    Graymatrix[i, j] = 0;              // Set pixel to 0 (Black)
                else
                    Graymatrix[i, j] = 255;            // Set pixel to 1 (White)
            }
        }

        IntPtr imgPtr = iImage.iVarPtr(ref Graymatrix[0, 0]);
        err = iImage.iPointerToiImage(GrayImage1, imgPtr, Width, Height);
        if (err != E_iVision_ERRORS.E_OK)              // Check the status from functions
        {
            MessageBox.Show(err.ToString(), "Error");
            return;
        }

        hbitmap = iImage.iGetBitmapAddress(GrayImage1); // transform to hbitmap for PictureBox
        if (pictureBox1.Image != null)                 //If there is an image on the Picturebox
            pictureBox1.Image.Dispose();               //clear Picturebox image
        pictureBox1.Image = System.Drawing.Image.FromHbitmap(hbitmap); // shows image
        pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;        //Set PictureBox size mode
        pictureBox1.Refresh();                         // refresh to update the Picturebox

    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }
}

}
好像下面要改,但我不知道要怎麼改,我在這邊卡關了
for (int j = 0; j < Width; j++) // j index for rows ( 0~Width-1)
{
if (Graymatrix[i, j] < Threshold) // Compare if the image intensity of each pixel smaller than threshold
Graymatrix[i, j] = 0; // Set pixel to 0 (Black)
else
Graymatrix[i, j] = 255; // Set pixel to 1 (White)
請各路好手幫幫忙