Image Compression Help

[wagswvu]

Below I wrote a simple app that take an image (tif) file and rotates it (in this case 180 degrees) and saves it back out, which was my goal for this proof of concept. However, in order for the saved image to be in the same compression as the original I had to use the "EncoderParameter" and specify the compression, which in this case was CCITT4(Fax Group 4). My question is there a way to detect the compression from the original image? because not all our images we store are compressed in CCITT4.

Dim image As Bitmap

        Dim eps As Imaging.EncoderParameters = New Imaging.EncoderParameters(1)

        image = image.FromFile("C:\tiff\Page04.tif", True)

        image.RotateFlip(RotateFlipType.Rotate180FlipNone)

        Dim CodecInfo() As System.Drawing.Imaging.ImageCodecInfo
        Dim TifCodec As System.Drawing.Imaging.ImageCodecInfo

        CodecInfo = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders
        TifCodec = CodecInfo(3)

        eps.Param(0) = New Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Compression, _
        System.Drawing.Imaging.EncoderValue.CompressionCCITT4)

        image.Save("C:\tiff\fliptest11.tif", TifCodec, eps)

 

[drummergirl89]

When I run this code I get an error on the last line that reads: "ArgumentException was Unhandled, Parameter is Not Valid"
Why is this?

 

[JohnH]

When I run this code I get an error on the last line that reads: "ArgumentException was Unhandled, Parameter is Not Valid"
Why is this?

Most likely because your image is not compatible with the CCITT4 compression. TiffCompressOption Enumeration (System.Windows.Media.Imaging)

The Ccitt3, Ccitt4, and Rle require that the PixelFormat value be set to BlackWhite.

 

[drummergirl89]

Thank you very much for your help.