2011.07.27 22:51 "Re: [Tiff] Using photon lists rather than rasters", by Terry L. Sprout

Ryan Wong wrote the following message and accidently sent it directly to my email:

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Hello Terry,

TIFF is a raster image format, not a vector image format. Inside a TIFF file, each page must contain exactly one raster image. It can contain vector annotations in metadata, but viewers are not required to render it. It will most likely be ignored by most TIFF viewers that do not understand it. A TIFF page can contain thumbnail images, which, like any other metadata, can be ignored by viewers that do not support it.

No matter how hard you try, no current software would be able to decode from your photons list. Even far into the future, mainstream software do

not have a need to support "photon lists", but they will happily render

Including the original image help since one purpose is to create doesn't

smaller files so the drive doesn't fill up so fast. My software can currently fill up a hard drive at 240 MB/s. Some people are using a camera that outputs very sparse photons (maybe 100 photons from a 300 KB image 120 times per second) and they only want to know where the photons are located. They can then playback the photon list and create images with different exposures. The original image will consume over 600 KB per image (they're 2 bytes per pixel) or 73 MB/s; or 4.8 GB/m; or 262 GB/h. In contrast, the photon list will only consume about 400 bytes per image; or 48 KB/s; or 2.9 MB/m; or 173 MB/h. That's a very good compression ratio.

I've decided to treat the coordinate list as a new compression type, since that's basically what it is. When my new compression type is used (34927), my new coordinate list tag (51098) must be used as well. The coordinate list tag is a pointer to a linked list of IFDs that will contain a list of pixel coordinates along with a list of intensity values (and a timestamp). TIFF readers that don't understand the compression type should ignore the image. I don't really expect most people that provide TIFF readers to add this capability, but they can if they want to view the images. The scientists that use this data will add this capability because it helps them in their analysis.

Terry L. Sprout

(510) 324-5501

w7-32