c# - 在 tiff 查看器中压缩图像

Question

我为我的 Web 应用程序创建了 Tiff 文件查看器，它运行良好。但问题是我需要以原始尺寸显示一些大图像（4000 X 2000 - 5+ MB）。

是否可以压缩图像的大小，然后将流发送到 ashx 页面上的响应流？

请注意，我所有的图像都是扫描的黑白图像。但是为了预防起见，我想检查是否将特定于黑白图像的压缩算法应用于图像。

查看以下 TiffHelper 类的代码

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Drawing.Drawing2D;

public class TiffHelper
{
    public static int GetPageCount(String filePath)
    {
        int pageCount = 0;
        try
        {
            using (Image img = Image.FromStream(
                                new FileStream(filePath,
                                 FileMode.Open,
                                 FileAccess.Read,
                                 FileShare.ReadWrite)
                           ))
            {
                pageCount = img.GetFrameCount(FrameDimension.Page);
            }
        }
        catch (Exception ex)
        {
            CException.SuppressException(ex);
            pageCount = -1;
        }

        return pageCount;
    }

    public static Image GetTiffImage(String sourceFile, int pageNumber, int thumbnailSize, int degree)
    {
        MemoryStream ms = null;
        Image sourceImage = null;
        Image returnImage = null;

        try
        {
            sourceImage = Image.FromStream(
                                new FileStream(sourceFile,
                                 FileMode.Open,
                                 FileAccess.Read,
                                 FileShare.ReadWrite)
                           );
            ms = new MemoryStream();
            FrameDimension FrDim = new FrameDimension(sourceImage.FrameDimensionsList[0]);
            sourceImage.SelectActiveFrame(FrDim, pageNumber - 1);

            sourceImage.Save(ms, ImageFormat.Tiff);

            /*
            EncoderParameter qualityParam = new EncoderParameter(Encoder.Quality, 90);
            ImageCodecInfo tiffCodec = GetEncoderInfo("image/tiff");
            EncoderParameters encoderParams = new EncoderParameters(1);
            encoderParams.Param[0] = qualityParam;

            sourceImage.Save(ms, tiffCodec, encoderParams); 
            */

            /*
            EncoderParameters iparams = new EncoderParameters(2);
            iparams.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.SaveFlag, (long)EncoderValue.MultiFrame);
            iparams.Param[1] = new EncoderParameter(System.Drawing.Imaging.Encoder.Compression, (long)EncoderValue.CompressionCCITT4);
             * 
            sourceImage.Save(ms, GetEncoderInfo("image/tiff"), iparams);
            */

            int height = sourceImage.Height;
            int width = sourceImage.Width;

            if (thumbnailSize > 0)
            {
                if (sourceImage.Width < sourceImage.Height)
                {
                    width = thumbnailSize;
                    height = sourceImage.Height * thumbnailSize / sourceImage.Width;
                }
                else
                {
                    width = sourceImage.Width * thumbnailSize / sourceImage.Height;
                    height = thumbnailSize;
                }
            }

            //returnImage = ResizeImage(Image.FromStream(ms), new Size(width, height));

            returnImage = Image.FromStream(ms).GetThumbnailImage(width, height, null, IntPtr.Zero);
            returnImage.RotateFlip(GetFlipType(degree));
        }
        catch (Exception ex)
        {
            CException.SuppressException(ex);
        }
        finally
        {
            ms.Dispose();
            sourceImage.Dispose();
        }

        return returnImage;
    }

    private static Image ResizeImage(Image imgToResize, Size size)
    {
        int sourceWidth = imgToResize.Width;
        int sourceHeight = imgToResize.Height;

        float nPercent = 0;
        float nPercentW = 0;
        float nPercentH = 0;

        nPercentW = ((float)size.Width / (float)sourceWidth);
        nPercentH = ((float)size.Height / (float)sourceHeight);

        if (nPercentH < nPercentW)
            nPercent = nPercentH;
        else
            nPercent = nPercentW;

        int destWidth = (int)(sourceWidth * nPercent);
        int destHeight = (int)(sourceHeight * nPercent);

        Bitmap b = new Bitmap(destWidth, destHeight);
        Graphics g = Graphics.FromImage((Image)b);

        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.SmoothingMode = SmoothingMode.HighSpeed;
        g.PixelOffsetMode = PixelOffsetMode.HighSpeed;
        g.CompositingQuality = CompositingQuality.HighQuality;

        g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);
        g.Dispose();

        return (Image)b;
    }

    private static ImageCodecInfo GetEncoderInfo(string mimeType)
    {
        ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();

        for (int i = 0; i < codecs.Length; i++)
        {
            if (codecs[i].MimeType == mimeType)
            {
                return codecs[i];
            }
        }

        return null;
    }

    private static RotateFlipType GetFlipType(int degree)
    {
        switch (degree)
        {
            case 90:
                return RotateFlipType.Rotate90FlipNone;
            case 180:
                return RotateFlipType.Rotate180FlipNone;
            case 270:
                return RotateFlipType.Rotate270FlipNone;
            case -90:
                return RotateFlipType.Rotate90FlipXY;
            case -180:
                return RotateFlipType.Rotate180FlipNone;
            case -270:
                return RotateFlipType.Rotate270FlipXY;
            default:
                return RotateFlipType.RotateNoneFlipNone;
        }
    }
}