C#图片处理类：ImageLibrary

  public class ImageLibrary
{

    /// <summary>
    /// 图片转换为数组
    /// </summary>
    /// <param name="img">图片实例</param>
    /// <returns></returns>
    public static byte[] ConvertImage2Bytes(Image img)
    {
        if (img == null) return null;
        MemoryStream ms = new MemoryStream();
        try
        {
            Bitmap bmp = new Bitmap(img);
            bmp.Save(ms, ImageFormat.Bmp);
            byte[] bs = ms.ToArray();
            ms.Close();
            return bs;
        }
        catch { ms.Close(); return null; }
    }
    /// <summary>
    /// 按宽度比例缩小图片
    /// </summary>
    /// <param name="imgSource">原始图片</param>
    /// <param name="MAX_WIDTH">最大宽度</param>
    /// <returns></returns>
    public static Image ResizeImage(Image imgSource, int MAX_WIDTH, int MAX_HEIGHT)
    {
        Image imgOutput = imgSource;

        Size size = new Size(0, 0); //用于存储按比例计算后的宽和高参数

        if (imgSource.Width <= 3 || imgSource.Height <= 3) return imgSource; //3X3大小的图片不转换

        //按宽度缩放图片
        if (imgSource.Width > MAX_WIDTH) //计算宽度
        {
            double rate = MAX_WIDTH / (double)imgSource.Width; //计算宽度比例因子

            size.Width = Convert.ToInt32(imgSource.Width * rate);
            size.Height = Convert.ToInt32(imgSource.Height * rate);
            imgOutput = imgSource.GetThumbnailImage(size.Width, size.Height, null, IntPtr.Zero);
        }

        //按高度缩放图片
        if (imgOutput.Height > MAX_HEIGHT)//计算高度
        {
            double rate = MAX_HEIGHT / (double)imgOutput.Height; //计算宽度比例因子

            size.Width = Convert.ToInt32(imgOutput.Width * rate);
            size.Height = Convert.ToInt32(imgOutput.Height * rate);
            imgOutput = imgSource.GetThumbnailImage(size.Width, size.Height, null, IntPtr.Zero);
        }

        return imgOutput;
    }


    /// <summary>
    /// 生成空图标
    /// </summary>
    /// <param name="Width"></param>
    /// <param name="Height"></param>
    /// <param name="Text"></param>
    /// <returns></returns>
    private static Image GenerateNullImage(int Width, int Height, string Text)
    {
        Bitmap bmp = new Bitmap(Width, Height);
        Graphics g = Graphics.FromImage(bmp);
        g.FillRectangle(Brushes.PaleVioletRed, new Rectangle() { X = 0, Y = 0, Height = 100, Width = 100 });

        Font font = new Font("宋体", 8);

        StringFormat sf = new StringFormat()
        {
            Alignment = StringAlignment.Center,
            LineAlignment = StringAlignment.Center
        };
        g.DrawString(Text, font, Brushes.Black, new Rectangle(0, 0, Width, Height), sf);


        return bmp;
    }

    //public static Image LoadImageByFileEx(string fileName, int ImageSize)
    //{
    //    if (File.Exists(fileName))
    //        return Image.FromFile(fileName);
    //    else
    //    {
    //        string str = String.Format("No {0}", System.IO.Path.GetFileNameWithoutExtension(fileName));
    //        return GenerateNullImage(ImageSize, ImageSize, String.Format("No {0}", str));
    //    }
    //}

    public static Image LoadImageByFileEx(string fileName, int ImageSize)
    {
        if (File.Exists(fileName))
            return Image.FromFile(fileName);
        else
            return GenerateNullImage(ImageSize, ImageSize, "No ImgFile");
    }

    public static Image LoadImageByFileEx(string file)
    {
        if (File.Exists(file))
            return Image.FromFile(file);
        else
            return GenerateNullImage(24, 24, String.Format("No ImgFile"));
    }

    public static Image LoadImageByFile(string file)
    {
        if (File.Exists(file))
            return Image.FromFile(file);
        else
            return null;
    }


    public static Bitmap LoadBitmapByFile(string file)
    {
        if (File.Exists(file))
            return new Bitmap(Bitmap.FromFile(file));
        else
            return null;
    }

    /// <summary>
    /// 加载ChildForm ICO
    /// </summary>
    /// <param name="SimpleImgFileName"></param>
    /// <returns></returns>
    public static Icon LoadFormIcon(string SimpleImgFileName)
    {
        Bitmap bmp = new Bitmap(LoadImageByFileEx(SimpleImgFileName, 16));
        return Icon.FromHandle(bmp.GetHicon());

    }
}