2011.07.27 16:39 "[Tiff] Using photon lists rather than rasters", by Terry L. Sprout

2011.07.28 18:30 "Re: [Tiff] Using photon lists rather than rasters", by Terry L. Sprout

This has been an interesting thread. The final decision is to include the image in the TIFF file and simply add the photon list as private meta data. We will use integration methods to achieve compression (integrating 1000 16-bit images gives a 2000:1 compression ratio) and the TIFF file will include photon lists from all images used in the integration. That will allow all TIFF readers to display the integrated image and it will allow my software (and any other software that knows how to read the photon lists) to use the photon lists to create images with shorter exposures if desired. Including the image also allows users to browse the hard drive when trying to find a specific set of images.

In the future, I may choose to compress images further by setting the bits/sample to the largest bit-depth in the image and then packing the image. So images that are not integrated will be 1-bit/sample images, which gives me another 8:1 compression ratio. I'm not sure if there is enough value in packing bits, however, so I may never do it.

I do want to mention one other thought. Some of you have indicated that images described with a coordinate map is not an image. I am not aware that the definition of an image has anything to do with its representation. An image is the final result that is presented to the user. A 2D array of intensities is no more an image than a list of vectors or a list of coordinates. If an image is defined as a 2D array of intensities, then I guess a 2D array of any A/D devices would also be an image. So to argue that a representation of an image as a list of coordinates does not fit the TIFF specification simply because it doesn't fit your definition of an image is a bad argument. It is better to say a TIFF image is expected to be comprised of rasters and not coordinate maps.

So I am in agreement that trying to use the TIFF structure for a photon list with no raster image is an incorrect use of TIFF. If I want a private use of a TIFF file, I might as well create my own file structure (which would be easier) and provide instructions to anyone that needs to read them.

Thank you all for the opportunity to have this discussion.

Terry L. Sprout

From: tiff-bounces@lists.maptools.org [mailto:tiff-bounces@lists.maptools.org] On Behalf Of

rwong_002@hotmail.com

The idea about a better predictor to improve compression of niche scientific images is interesting. Along the same direction, Terry could really use the new compression type for that. Think about that: if it's a new predictor that nobody today knows how to decode, and if it's much more advanced than today's "TIFF predictor" (even though it is indeed a predictor in mathematical/pedantic terms), it doesn't hurt to make its own compression type. As for the photon images, it will require something superbly advanced algorithms, something that blends several existing advanced algorithms together that nobody has seen before. Like: multi-resolution (or progressive-resolution), some kind of CABAC (which is both context-sensitive and uses arithmetic coding), etc. That said, the larger TIFF community may try to compel you to (1) open source your implementation and (2) give up, or sign over all intellectual rights and copyrights of that specification, and for that matter (3) it still leaves you vulnerable to patent lawsuits while the larger TIFF community just sit and watch. Therefore, it's important to remember that ultimately you have to decide what to do with your invention; you may decide whether to open it or not. If in doubt, talk to your company or employer lawyer. Thanks,

rwong_002@hotmail.com <mailto:rwong_002@hotmail.com>

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