Question

I am working on a system that stores many images in a database as byte[]. Each byte[] is a multi page tiff already, but I have a need to retrieve the images, converting them all to one multi page tiff. The system was previously using the System.Drawing.Image classes, with Save and SaveAdd - this was nice in that it saves the file progressively, and therefore memory usage was minimal, however GDI+ concurrency issues were encountered - this is running on a back end in COM+.

The methods were converted to use the System.Windows.Media.Imaging classes, TiffBitmapDecoder and TiffBitmapEncoder, with a bit of massaging in between. This resolved the concurrency issue, but I am struggling to find a way to save the image progressively (i.e. frame by frame) to limit memory usage, and therefore the size of images that can be manipulated is much lower (i.e. I created a test 1.2GB image using the GDI+ classes, and could have gone on, but could only create a ~600MB file using the other method).

Is there any way to progressively save a multi page tiff image to avoid memory issues? If Save is called on the TiffBitmapEncoder more than once an error is thrown.

Answer 1

I think I would use the standard .NET way to decode the tiff images and write my own tiff encoder that can write progressively to disk. The tiff format specifications are public.

Decoding a tiff is not that easy, that s why I would use the TiffBitmapDecoder for this. Encoding is is easier, so I think it is doable to write an encoder that you can feed with separate frames and that is writing the necessary data progressively to disk. You ll probably have to update the header of the resulting tiff once you are ready to update the IFD (Image File Directory) entry.

Good luck!

Answer 2

I ve done this via LibTIFF.NET I can handle multi-gigabyte images this way with no pain. See my question at

Using LibTIFF from c# to access tiled tiff images

Although I use it for tiled access, the memory issues are similar. LibTIFF allows full access to all TIFF functions, so files can be read and stored in a directory-like manner.

The other thing worth noting is the differences between GDI on different windows versions. See GDI .NET exceptions.

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