图片转换成字符 根据灰度值填充字符-单文件单线程版

private void button1_Click(object sender, EventArgs e)
{
//打开文件
OpenFileDialog open = new OpenFileDialog();
open.Filter = "jpeg图片文件|*.jpg";
if (open.ShowDialog() != DialogResult.OK)
return;
string filePath = open.FileName;
//打开图片，显示原始图
Image img = Image.FromFile(filePath);
sourcePicturebox.Image =img ;
//再次读取一次图潘
Bitmap bitmap = new Bitmap(img);
//锁定图片处理区域
Rectangle rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
BitmapData bmpData = bitmap.LockBits(rect, ImageLockMode.ReadWrite, bitmap.PixelFormat);
//初始化字符串数组
string[] str = new string[bitmap.Height];
//不安全代码块
unsafe
{
//获取首指针
byte* ptr = (byte*)(bmpData.Scan0);
for (int height = 0; height < bmpData.Height; height++)
{
//由于测试图片是32RGB图，所以，ptr一次移动四位
for (int width = 0; width < bmpData.Width; width++,ptr+=4)
{
str[height] += ((byte)(0.333 * ptr[0] + 0.333 * ptr[1] + 0.333 * ptr[2])) > 128 ? "*" : " ";
}
//为防止图片数据占用不为4的倍数，所以这里用stride，跳过多余的字节
ptr += bmpData.Stride - bmpData.Width * 4;
}
}
//图片解锁
bitmap.UnlockBits(bmpData);
//初始化打印字符参数，以及新建一个空白图片
//空白图片大小。。。。。测试得到的。后续改进
Font font=new System.Drawing.Font ("宋体",20.5f);
Bitmap resultBitmap = new Bitmap(img.Width * 14, img.Height * 14);
Graphics graphics = Graphics.FromImage(resultBitmap);
graphics.Clear(Color.White);
SolidBrush brush=new SolidBrush(Color.Black);
//打印字符，一次一行
for (int i = 0; i < img.Height; i++)
{
graphics.DrawString(str[i], font, brush,0,i*14);
}
//MessageBox.Show(font.GetHeight().ToString());
resultPicturebox.Image = resultBitmap;
//文件保存
SaveFileDialog saveDialog = new SaveFileDialog();
saveDialog.Filter = "jpeg图片文件|*.jpg";
if(saveDialog.ShowDialog()==DialogResult.OK)
resultBitmap.Save(saveDialog.FileName, ImageFormat.Jpeg);
}