Replace an Image in an existing Multiple Page Tiff using .Net

Using .Net how do I replace the first page of a multiple page tiff file with开发者_如何学Python a new image. Preferable without create a new file.

I think you could not do it without creating another file.

You could read all the images first, replace the image you want to replace, close the original source, and then replace the file with the new multi-page TIFF, but I believe it will use a lot of memory. I would read an image at a time, and write it to a new file and, as the last step, change the file names.

Something like:

 // open a multi page tiff using a Stream
 using(Stream stream = // your favorite stream depending if you have in memory or from file.)
 {
 Bitmap bmp = new Bitmap(imagePath);

 int frameCount = bmp.GetFrameCount(FrameDimension.Page);

 // for a reference for creating a new multi page tiff see: 
 // http://www.bobpowell.net/generating_multipage_tiffs.htm
 // Here all the stuff of the Encoders, and all that stuff.

 EncoderParameters ep = new EncoderParameters(1);
 ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.MultiFrame);

 Image newTiff = theNewFirstImage;

 for(int i=0; i<frameCount; i++)
 {
     if(i==0)
     {
          // Just save the new image instead of the first one.
          newTiff.Save(newFileName, imageCodecInfo, Encoder);
     }
     else
     {
          Bitmap newPage = bmp.SelectActiveFrame(FrameDimension.Page);
          newTiff.SaveAdd(newPage, ep);
     }
 }

 
 ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.Flush);
 newTiff.SaveAdd(ep);
 }
 // close all files and Streams and the do original file delete, and newFile change name... 

Hope it helps. For questions in .NET imaging, the Bob Powell page has a lot of good stuff.

This is fairly easy to do. There's source code on this CodeProject tutorial page that will help you do what you want.

Essentially, you'll need to make a call to Image.GetFrameCount() which will give you the number of images in your multi-page TIFF (just to confirm that you actually have a multi-page TIFF).

You might need to experiment with how you save your resulting TIFF - you may need to reassemble the TIFF manually, or you might be able to edit/replace the image directly before writing the TIFF back to disk.