<p>This is exactly what I wanted. I'll try and implement this and let you know how it goes.</p>
<p><blockquote type="cite">On Jan 28, 2011 7:11 PM, "David Gobbi" <<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>> wrote:<br><br><p><font color="#500050">On Fri, Jan 28, 2011 at 7:45 PM, Jonathan Morra <<a href="mailto:jonmorra@gmail.com">jonmorra@gmail.com</a>> wrote:</font></p>
<div class="gmail_quote"><p><font color="#500050">><br>> I have a binary vtkImageData that a user can modify through some tools I provide them. However,...</font></p><div>No, but it shouldn't be too hard to do this. You can get a pointer to the data by calling GetScalarPointer() on the image data. The size of this data (in bytes) will be product of the Dimensions, the NumberOfScalarComponents, and the ScalarSize.</div>
<div><br></div><div>So, you should easily be able to compute a bytewise difference between two images. There's no reason to write a new filter for this, since it's just a simple for() loop. Then, you can use vtkDataCompressor::Compress() to compress the diff so that it can be efficiently stored. By doing everything bytewise, you don't have to worry about different datatypes, and you shouldn't lose anything in terms of efficiency.</div>
<div><br></div><div>If the image changes in size, then you could store a compressed copy of the full image rather than dealing with the difficulty of diffing images of different sizes.</div><div><br></div><div>I hope this helps.</div>
<div><br></div><div> - David</div><div><br></div></div>
</blockquote></p>