Convert multipage TIFF to PNG .Net

Question

I am able to convert a single page TIFF to a PNG in .Net, however, how would I do this for a multipage TIFF?

Answer 1

thanks @Tom Halladay

I'll provide a c# version of your code

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 2

You should select active frame (page) in a loop and convert each tiff page to a 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
}

This code assumes that you can load Tiff image in System.Drawing.Bitmap object.

Answer 3

Complete example without the need for 3'rd party assemblies:

' 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