c# - TIFFビューアで画像を圧縮

Question

Web アプリケーション用の Tiff ファイル ビューアーを作成しましたが、うまく機能しています。しかし、問題は、元のサイズで表示する必要がある大きな画像 (4000 X 2000 - 5 MB 以上) があることです。

画像のサイズを圧縮してから、ストリームを ashx ページの Response Stream に送信することはできますか?

私の画像はすべてスキャンされた白黒画像であることに注意してください。ただし念のため、白黒画像特有の圧縮アルゴリズムが画像に適用されているかどうかを確認したいと思います。

以下の TiffHelper クラスのコードを見てください

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;
        }
    }
}