.net 加水印 图片变大很多，原图300 KB 缩略图竟然500kb 什么世道？

Question

有没有别人写好的.net 下图片处理的类库？？？  处理好的图片要返回 Image 对象，而不是保存到一个路径
因为我要远程传输到其它服务器上 ，还要把 图片转换成 byte 字节的形式传输到FTP 服务器上

Answer 1

我自己写的图片缩放的类库using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using ImageManipulation;namespace Zz.Common
{
    public class ImageHelper
    { 
        /// <summary>
        /// 给图片加水印
        /// </summary>
        /// <param name="originalImg"></param>
        /// <param name="waterImg"></param>
        /// <param name="trbl"></param>
        /// <returns></returns>
        public static Image WaterImage(Image originalImg, Image waterImg, WaterTRBL trbl)
        {            Image image = (Image)originalImg.Clone();
            using (Graphics g = Graphics.FromImage(image))
            {
                Rectangle r = new Rectangle();
                r.Height = waterImg.Height;
                r.Width = waterImg.Width;
                if (trbl.Top != null)
                {
                    r.Y = (int)trbl.Top;
                }                if (trbl.Right != null)
                {
                    r.X = originalImg.Width - waterImg.Width - (int)trbl.Right;
                }                if (trbl.Bottom != null)
                {
                    r.Y = originalImg.Height - waterImg.Height - (int)trbl.Bottom;
                }                if (trbl.Left != null)
                {
                    r.X = (int)trbl.Left;
                }                g.DrawImage(waterImg, r, 0, 0, waterImg.Width, waterImg.Height, GraphicsUnit.Pixel);
            }            return image;
        }        /// <summary>
        /// 等比缩放图片
        /// </summary>
        /// <param name="imgPhoto"></param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <returns></returns>
        public static System.Drawing.Image GetImageThumbnail(System.Drawing.Image imgPhoto, int width, int height)
        {            int sourceWidth = imgPhoto.Width;
            int sourceHeight = imgPhoto.Height;
            //int x, y;  //位置
            int w, h; //缩放后的宽和高            if (sourceWidth > width || sourceHeight > height)
            {
                decimal wPercent = (decimal)sourceWidth / width;
                decimal hPercent = (decimal)sourceHeight / height;
                decimal nPercent;
                if (hPercent > wPercent)
                {
                    nPercent = hPercent;
                }
                else
                {
                    nPercent = wPercent;
                }                w = (int)Math.Round(sourceWidth / nPercent, 0);
                h = (int)Math.Round(sourceHeight / nPercent, 0);            }
            else
            {
                w = sourceWidth;
                h = sourceHeight;
            }
            try
            {                Bitmap bmPhoto = new Bitmap(w, h, PixelFormat.Format24bppRgb);
                                //bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);
                Graphics grPhoto = Graphics.FromImage(bmPhoto);
                //grPhoto.Clear(Color.White);
                //grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
                //设置高质量插值法 
                grPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;                //设置高质量,低速度呈现平滑程度 
                grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;                //清空画布并以透明背景色填充 
                grPhoto.Clear(System.Drawing.Color.Transparent);
                grPhoto.DrawImage(imgPhoto,
                    new Rectangle(0, 0, w, h),///它指定所绘制图像的位置和大小。
                    new Rectangle(0, 0, sourceWidth, sourceHeight),///它指定 image 对象中要绘制的部分。
                    GraphicsUnit.Pixel);///它指定 srcRect 参数所用的度量单位。                grPhoto.Dispose();                if (imgPhoto.RawFormat == ImageFormat.Gif || imgPhoto.RawFormat.Guid == ImageFormat.Gif.Guid)
                {
                    OctreeQuantizer quantizer = new OctreeQuantizer(255, 8);
                    using (Bitmap quantized = quantizer.Quantize(imgPhoto))
                    {
                        return quantized;
                    }
                }
                else
                {
                    return bmPhoto;
                }            }
            catch
            {                return null;
            }
        }        public static System.Drawing.Image GetImageThumbnail(System.Drawing.Image imgPhoto, int width)
        {            int sourceWidth = imgPhoto.Width;
            int sourceHeight = imgPhoto.Height;
            //int x, y;  //位置
            int w, h; //缩放后的宽和高            if (sourceWidth > width)
            {
                decimal nPercent = (decimal)sourceWidth / width;
                w = (int)Math.Round(sourceWidth / nPercent, 0);
                h = (int)Math.Round(sourceHeight / nPercent, 0);
            }
            else
            {
                w = sourceWidth;
                h = sourceHeight;
            }
            try
            {
                Bitmap bmPhoto = new Bitmap(w, h);
                //bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);
                Graphics grPhoto = Graphics.FromImage(bmPhoto);
                //grPhoto.Clear(Color.White);
                //grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
                //设置高质量插值法 
                grPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;                //设置高质量,低速度呈现平滑程度 
                grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;                //清空画布并以透明背景色填充 
                grPhoto.Clear(System.Drawing.Color.Transparent);
                                grPhoto.DrawImage(imgPhoto,
                    new Rectangle(0, 0, w, h),///它指定所绘制图像的位置和大小。
                    new Rectangle(0, 0, sourceWidth, sourceHeight),///它指定 image 对象中要绘制的部分。
                    GraphicsUnit.Pixel);///它指定 srcRect 参数所用的度量单位。                grPhoto.Dispose();                if (imgPhoto.RawFormat == ImageFormat.Gif || imgPhoto.RawFormat.Guid == ImageFormat.Gif.Guid)
                {
                    OctreeQuantizer quantizer = new OctreeQuantizer(255, 8);
                    return quantizer.Quantize(bmPhoto);
                }
                else
                {
                    return bmPhoto;
                }            }
            catch
            {                return null;
            }
        }        public static System.Drawing.Image GetZipImageThumbnail(System.Drawing.Image imgPhoto, int width, int height, int flag)
        {
            Image thumbnail = GetImageThumbnail(imgPhoto, width, height);
            return ZipImage(thumbnail, flag);
        }
        public static System.Drawing.Image GetZipImageThumbnail(System.Drawing.Image imgPhoto, int width, int flag)
        {
            Image thumbnail = GetImageThumbnail(imgPhoto, width);
            return ZipImage(thumbnail, flag);        }
        /// <summary>
        /// 压缩图片
        /// </summary>
        /// <param name="imgPhoto"></param>
        /// <param name="flag"></param>
        /// <returns></returns>
        public static System.Drawing.Image ZipImage(System.Drawing.Image imgPhoto, int flag)
        {
            EncoderParameters ep = new EncoderParameters();
            long[] qy = new long[1];
            qy[0] = flag;//设置压缩的比例1-100
            EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
            ep.Param[0] = eParam;            try
            {
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICIinfo = null;
                for (int x = 0; x < arrayICI.Length; x++)
                {
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICIinfo = arrayICI[x];
                        break;
                    }
                }                MemoryStream ms = new MemoryStream();
                if (jpegICIinfo != null)
                {                    imgPhoto.Save(ms, jpegICIinfo, ep);//dFile是压缩后的新路径
                }
                else
                {
                    imgPhoto.Save(ms, imgPhoto.RawFormat);
                }                System.Drawing.Image zipImage = System.Drawing.Image.FromStream(ms);
                return zipImage;
            }
            catch
            {
                return null;
            }
        }
    }
}

Answer 2

       public class WaterTRBL
        {
            public WaterTRBL()
            {            }
            int? top = null, right = null, bottom = null, left = null;
            public WaterTRBL(int? top, int? right, int? bottom, int? left)
            {
                this.top = top;
                this.right = right;
                this.bottom = bottom;
                this.left = left;
            }            public int? Top
            {
                get { return top; }
                set { top = value; }
            }
            public int? Right
            {
                get { return right; }
                set { right = value; }
            }            public int? Bottom
            {
                get { return bottom; }
                set { bottom = value; }
            }            public int? Left
            {
                get { return left; }
                set { left = value; }
            }
        }

Answer 3

我想问下我该使用哪种模式，最起码图片质量要和原图一样的？
InterpolationMode.Default;？？？
InterpolationMode.Bicubic？？