Converting a multipage tiff to a gif

Question

User-1712672948 posted

Hi Folks

As mentioned I am having a problem converting a multipage tif to a mulitpage gif file. I am able to convert the tif file to gif but it loses any multipages. Single file pages are not a problem.

This is a simple version of the code I am using

        Dim bm As Bitmap = Bitmap.FromFile("C:\S740368.tif")
        bm.Save("C:\S740368.gif", System.Drawing.Imaging.ImageFormat.Gif)

Is it possible? I am using ASP.NET 2.0 but will be soon moving to 3.5. So is it perhaps possible with 3.5?

Thanks

Answer 1

User-987726656 posted

I think you should have a look at the SelectActiveFrame and SaveAdd methods of the Image class in System.Drawing.Image.

By using SelectActiveFrame in a loop you should be able to step through the pages of the input tiff and use SaveAdd to add them to the new output file.

 /Per

Answer 2

User-1712672948 posted

 Thanks Persa. I'll try that and let you know how I get on.

 

Answer 3

User-1712672948 posted

Hi Per   

I've tried as you suggested and got very close to what I want to achieve. But I am still having problems with the SaveAdd fucntion below. I get an error stating:
'An unhandled exception of type 'System.Runtime.InteropServices.ExternalException' occurred in system.drawing.dll
Additional information: A generic error occurred in GDI+.'

I am able to loop through the tif image pages and save these as individual gif images by uncommenting the mygif.Save("c:\test_" & i & ".gif") line below. But my problem still remains that I cannot create a mulit-page gif image.

Am I perhaps using the SaveAdd function incorrectly? Do I need to add a reference?

Here is my code

Imports System.Drawing.Imaging
.
.
.
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim enc As Encoder = Encoder.SaveFlag
        Dim encparam As New EncoderParameter(enc, Long.Parse(EncoderValue.MultiFrame))
        Dim encparams As EncoderParameters = New EncoderParameters(1)
        encparams.Param(0) = encparam

        Dim mygif As Image = Image.FromFile("c:\test.tif")
        mygif.Save("c:\test.gif", ImageFormat.Gif)

        For i As Integer = 1 To mygif.GetFrameCount(FrameDimension.Page) - 1

            mygif.SelectActiveFrame(FrameDimension.Page, i)

            'mygif.Save("c:\test_" & i & ".gif")
            mygif.SaveAdd(mygif, encparams)

        Next

    End Sub

 
Thanks Per

Ian.

Answer 4

User-987726656 posted

I am sorry but a little more investigation gives that the GDI+ GIF encoder used can't create multiframe GIF images...

So I think you need some graphics toolkit with more advanced GIF functionality. One possibility is GifLib, have a look at http://www.codeplex.com/GifLib.

/Per