c# - 在 C# 中使用 libtiff 从一种 TIFF 格式转换为另一种

Question

我有一个使用 JPEG 格式的 TIFF，WPF/C# 无法通过 TiffBitmapDecoder 处理。我们的客户使用文件格式，我们当前的 C++ 和 Java 代码处理它。

我需要将其转换为可以使用 TiffBitmapDecoder 或标准 BitmapImage 显示的格式。看起来 C# 版本的 libtiff 是可行的方法，但我在代码中转换时运气不佳。

这是我的尝试 - 我总是以损坏的文件告终。

Boolean doSystemLoad = false;
Tiff tiff = null;

try
{
    tiff = Tiff.Open(file, "r");
}
catch (Exception e) // TIFF could not handle, let OS do it
{
    doSystemLoad = true;
}
if (tiff != null)
{
    width = Double.Parse(tiff.GetField(TiffTag.IMAGEWIDTH)[0].Value.ToString());
    height = Double.Parse(tiff.GetField(TiffTag.IMAGELENGTH)[0].Value.ToString());

    int bits = Int32.Parse(tiff.GetField(TiffTag.BITSPERSAMPLE)[0].Value.ToString());
    int samples = Int32.Parse(tiff.GetField(TiffTag.SAMPLESPERPIXEL)[0].Value.ToString());
    string compression = tiff.GetField(TiffTag.COMPRESSION)[0].Value.ToString();

    Console.WriteLine("Image is " + width + " x " + height + "   bits " + bits + " sample " + samples);
    Console.WriteLine("Compression " + compression);

    // We allow OS to load anything that is not JPEG compression
    doSystemLoad = compression.ToLower().IndexOf("jpeg") == -1;

    string tempFile = Path.GetTempFileName() + ".tiff";

    // Convert here then load converted via OS
    if (!doSystemLoad)
    {
        Console.WriteLine(">> Attempting to convert... " + tempFile);
        Console.WriteLine("  Scan line  " + tiff.ScanlineSize());

        Tiff tiffOut = Tiff.Open(tempFile, "w");
        tiffOut.SetField(TiffTag.IMAGEWIDTH, width);
        tiffOut.SetField(TiffTag.IMAGELENGTH, height);
        tiffOut.SetField(TiffTag.BITSPERSAMPLE, bits);
        tiffOut.SetField(TiffTag.SAMPLESPERPIXEL, samples);
        tiffOut.SetField(TiffTag.ROWSPERSTRIP, 1L);
        tiffOut.SetField(TiffTag.COMPRESSION, Compression.NONE);
        tiffOut.SetField(TiffTag.ORIENTATION, BitMiracle.LibTiff.Classic.Orientation.TOPLEFT);
        tiffOut.SetField(TiffTag.FAXMODE, FaxMode.CLASSF);
        tiffOut.SetField(TiffTag.GROUP3OPTIONS, 5);

        tiffOut.SetField(TiffTag.PHOTOMETRIC, Photometric.RGB);

        tiffOut.SetField(TiffTag.FILLORDER, FillOrder.MSB2LSB);
        tiffOut.SetField(TiffTag.PLANARCONFIG, PlanarConfig.CONTIG);
        tiffOut.SetField(TiffTag.RESOLUTIONUNIT, ResUnit.INCH);
        tiffOut.SetField(TiffTag.XRESOLUTION, 100.0);
        tiffOut.SetField(TiffTag.YRESOLUTION, 100.0);
        tiffOut.SetField(TiffTag.SUBFILETYPE, FileType.PAGE);
        tiffOut.SetField(TiffTag.PAGENUMBER, new object[] { 1, 1 });
        tiffOut.SetField(TiffTag.PAGENAME, "Page 1");

        Byte[] scanLine = new Byte[tiff.ScanlineSize() + 5000];
        for (int row = 0; row < height; row++)
        {
            tiff.ReadScanline(scanLine, row);
            tiffOut.WriteScanline(scanLine, row);
        }
        tiffOut.Dispose();
    }

    tiff.Dispose();

    Stream imageStreamSource = new FileStream(tempFile, FileMode.Open, FileAccess.Read, FileShare.Read);
    TiffBitmapDecoder decoder = new TiffBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
    BitmapSource bitmapSource = decoder.Frames[0];

    width = bitmapSource.Width;
    height = bitmapSource.Height;

    imageMain.Width = width;
    imageMain.Height = height;
    imageMain.Source = bitmapSource;
}

if (doSystemLoad)
{
    Stream imageStreamSource = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read);
    TiffBitmapDecoder decoder = new TiffBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
    BitmapSource bitmapSource = decoder.Frames[0];

    width = bitmapSource.Width;
    height = bitmapSource.Height;

    imageMain.Width = width;
    imageMain.Height = height;
    imageMain.Source = bitmapSource;
}

Answer 1

Kevin，LibTiff.Net 的早期版本之一有一个错误:没有自动调用 Flush。前段时间修好了。

此外，我们刚刚发布了 LibTiff.Net 2.2，支持 OJPEG(或旧 Jpeg，或原始 Jpeg)文件。如果新版本仍然相关，您可能想重试。