将多页 TIFF 转换为 PNG .Net

Question

我可以将单页 TIFF 转换为 .Net 中的 PNG，但是，对于多页 TIFF，我该如何执行此操作？

Answer 1

Imagemagick 几乎可以对图像执行任何操作，但可能需要一段时间才能正确执行由于有大量的选项可供选择。您可以使用互操作直接使用 Imagemagick，也可以使用 .NET 包装器。我只使用过互操作，所以我不知道 包装器 有多好或多坏。

private readonly ImageMagickObject.MagickImageClass _imageMagick = new ImageMagickObject.MagickImageClass();

var parameters = new object[] {sourcePath, destPath};
_imageMagick.Convert(ref parameters);

您必须在 ImageMagick 网站上自行查找这些参数。查看命令行参数的帮助并在论坛中搜索多页 tiff。我假设你想将 tiff 分割成多个 png ？然后也许是这样的：

convert multipage.tif single%d.png

Answer 2

无需第三方程序集的完整示例：

' MAIN CODE '

Dim ImageBitmap = Bitmap.FromStream(ImageStream)

Dim FrameCount = ImageBitmap.GetFrameCount(FrameDimension.Page)

Dim RunningHeight As Integer = 0
Dim MaxWidth As Integer = 0

For MeasurementFrameIndex As Integer = 0 To FrameCount - 1
    ImageBitmap.SelectActiveFrame(FrameDimension.Page, MeasurementFrameIndex)

    RunningHeight += ImageBitmap.Height
    MaxWidth = Math.Max(MaxWidth, ImageBitmap.Width)
Next

Dim CombinedBitmap As New Bitmap(MaxWidth, RunningHeight)
Dim RunningVerticalPosition As Integer = 0

For CombinationFrameIndex As Integer = 0 To FrameCount - 1
    ImageBitmap.SelectActiveFrame(FrameDimension.Page, CombinationFrameIndex)

    EmbedBitmap(ImageBitmap, CombinedBitmap, RunningVerticalPosition)

    RunningVerticalPosition += ImageBitmap.Height + 1
Next



    ' SUPPORT ROUTINES '

Private Shared Sub EmbedBitmap(
        SourceBitmap As Bitmap,
        ByRef DestinationBitmap As Bitmap,
        VerticalPosition As Integer)

    Dim SourceRectangle As New Rectangle(
        New Point(0, 0),
        New Size(SourceBitmap.Width, SourceBitmap.Height))

    Dim DestinationRectangle As New Rectangle(
        New Point(0, VerticalPosition),
        New Size(SourceBitmap.Width, SourceBitmap.Height))

    Using Canvas As Graphics = Graphics.FromImage(DestinationBitmap)
        Canvas.DrawImage(
            SourceBitmap,
            DestinationRectangle,
            SourceRectangle,
            GraphicsUnit.Pixel)
    End Using
End Sub

Answer 3

我知道这是一个老问题，但在 .NET Core、.NET5+ 等领域，它确实需要不同的解决方案，因为诸如 System.Drawing.Image 之类的本机 .NET 库仅适用于Windows 平台，不适用于 Linux 等其他部署。

因此，第三方选项实际上是现在的出路，ImageSharp 是一个很棒的选择开源选项。 。 。它很容易支持这一点，如下所示：

    using (var image = ImageSharp.Load(imageBytes))
    {
        //Process all possible Frames -- this same flow supports single images as well as Multi-page TIFF Images!
        for (var frameIndex = 0; frameIndex < image.Frames.Count; frameIndex++)
        {
            var clonedImageFrame = image.Frames.CloneFrame(frameIndex);
            await using var extractedImageStream = new MemoryStream();
            
            //There are a variety of overloads to extract in any format you like...
            //await clonedImageFrame.SaveAsTiffAsync(extractedImageStream).ConfigureAwait(false);
            //await clonedImageFrame.SaveAsJpegAsync(extractedImageStream, new JpegEncoder() { Quality = 80 }).ConfigureAwait(false);
            await clonedImageFrame.SaveAsPngAsync(extractedImageStream).ConfigureAwait(false);
            
            //Now you can do what you like with the extractedImageFrame. . . .
            var extractedImageFrameBytes = extractedImageStream.ToArray();
        
        }
    }

Answer 4

谢谢@Tom Halladay，

我将提供您的代码的 ac# 版本

private static Bitmap ConvertTiffToBitmapStream(byte[] tiffImage){
    System.Drawing.Image ImageBitmap = Bitmap.FromStream(new MemoryStream(tiffImage));
    int FrameCount = ImageBitmap.GetFrameCount(FrameDimension.Page);
    int RunningHeight = 0;
    int MaxWidth = 0;

    for (int MeasurementFrameIndex = 0; MeasurementFrameIndex <= FrameCount - 1; MeasurementFrameIndex++){
        ImageBitmap.SelectActiveFrame(FrameDimension.Page, MeasurementFrameIndex);
        RunningHeight += ImageBitmap.Height;
        MaxWidth = Math.Max(MaxWidth, ImageBitmap.Width);
    }

    Bitmap CombinedBitmap = new Bitmap(MaxWidth, RunningHeight);
    int RunningVerticalPosition = 0;

    for (int CombinationFrameIndex = 0; CombinationFrameIndex <= FrameCount - 1; CombinationFrameIndex++){
        ImageBitmap.SelectActiveFrame(FrameDimension.Page, CombinationFrameIndex);
        EmbedBitmap(new Bitmap(ImageBitmap), ref CombinedBitmap, RunningVerticalPosition);
        RunningVerticalPosition += ImageBitmap.Height + 1;
    }
    return CombinedBitmap;
}

private static void EmbedBitmap(Bitmap SourceBitmap, ref Bitmap DestinationBitmap, int VerticalPosition){
    Rectangle SourceRectangle = new Rectangle(new Point(0, 0), new Size(SourceBitmap.Width, SourceBitmap.Height));
    Rectangle DestinationRectangle = new Rectangle(new Point(0, VerticalPosition), new Size(SourceBitmap.Width, SourceBitmap.Height));

    using (Graphics Canvas = Graphics.FromImage(DestinationBitmap)){
        Canvas.DrawImage(SourceBitmap, DestinationRectangle, SourceRectangle, GraphicsUnit.Pixel);
    }
}

Answer 5

您应该循环选择活动帧（页面）并将每个 tiff 页面转换为 png。

int pageCount = 1;
try
{
    pageCount = bmp.GetFrameCount(FrameDimension.Page);
}
catch (Exception)
{
    // sometimes GDI+ throws internal exceptions.
    // just ignore them.
}

for (int page = 0; page < pageCount; page++)
{
    bmp.SelectActiveFrame(FrameDimension.Page, page);
    // save or otherwise process tiff page
}

此代码假设您可以在 System.Drawing.Bitmap 对象中加载 Tiff 图像。