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PO.Net Image.Save changes tiff from CTTIT Fax 4 to LZW
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  1. PO.Net Image.Save changes tiff from CTTIT Fax 4 to LZW
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    copied!<p>When I rotate an image, .Net switches the tiff encoding. Is there a way I can keep the CCITT Fax 4 (Group 4 Fax encoding) and not have it switch to LZW? Here is how I am rotating an image on disk.</p> <pre><code>System.Drawing.Image img = System.Drawing.Image.FromFile(input); //rotate the picture by 90 degrees img.RotateFlip(RotateFlipType.Rotate90FlipNone); img.Save(input, System.Drawing.Imaging.ImageFormat.Tiff); </code></pre> <p>Thanks, Brian</p> <p>Update: Here's the code based on the articles linked to below. I wanted to add the code here for completenes. Also, I set the horizontal resolution because the bitmaps defaults to 96 DPI.</p> <pre><code>//create an object that we can use to examine an image file System.Drawing.Image img = System.Drawing.Image.FromFile(input); //rotate the picture by 90 degrees img.RotateFlip(RotateFlipType.Rotate90FlipNone); // load into a bitmap to save with proper compression Bitmap myBitmap = new Bitmap(img); myBitmap.SetResolution(img.HorizontalResolution, img.VerticalResolution); // get the tiff codec info ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/tiff"); // Create an Encoder object based on the GUID for the Compression parameter category System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Compression; // create encode parameters EncoderParameters myEncoderParameters = new EncoderParameters(1); EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, (long)EncoderValue.CompressionCCITT4); myEncoderParameters.Param[0] = myEncoderParameter; // save as a tiff myBitmap.Save(input, myImageCodecInfo, myEncoderParameters); // get encoder info for specified mime type private static ImageCodecInfo GetEncoderInfo(String mimeType) { int j; ImageCodecInfo[] encoders; encoders = ImageCodecInfo.GetImageEncoders(); for (j = 0; j &lt; encoders.Length; ++j) { if (encoders[j].MimeType == mimeType) return encoders[j]; } return null; } </code></pre>
 

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