Re: 16 bits = 15 bits in Photoshop?
Re: 16 bits = 15 bits in Photoshop?
- Subject: Re: 16 bits = 15 bits in Photoshop?
- From: Ken Fleisher <email@hidden>
- Date: Sat, 16 Apr 2005 14:46:33 -0400
There is an obvious need for high-bit imaging that has been hinted at but not really stressed. I'm surprised that no one has placed more emphasis on high-dynamic range imaging (HDR). There are numerous formats for HDR imaging, but I know of none that use less than 12-bits, some 16-bit, and sometimes even 32-bits. You want examples of what can be done with 16-bits that can't be done with 8-bits? Check out these links:
http://www.cybergrain.com/tech/hdr/
http://www.hdrsoft.com/resources/dri.html (good explanations of HDR)
http://www.cis.rit.edu/mcsl/icam/hdr/ (Be sure to download and read the paper "Rendering HDR images". It has excellent side-by-side examples of the possibilities of well-mapped HDR images. Or do a google search for HDR or high-dynamic range imaging for many many more examples.)
Two points to stress:
1) It's true that this does not extend the dynamic range of your output devices. What it allows you do to, however, is to more intelligently select a gamut mapping for a particular output device that will maintain the best detail in all areas (i.e. both the indoors and the scene outside of a window can have detail--it doesn't have to be a trade-off anymore). One single image can act as the source for many different gamut mappings without compromising the results of any particular one.
2) There are now opportunities where the dynamic range of output devices exceeds anything we had previously, which implies that we do actually need to have a greater dynamic range in our images than can be supported by 8-bit/channel images. HDR displays are one example. Digital cinema isn't far behind (check out the new DLP specs). What does this mean? Imaging using the normal dynamic range for your image, with the extra headroom provided by an HDR display, you can actually present images that exhibit fluorescence and brilliance. That will be amazing to see!
Again , that may not change your opinion with respect to scanning an image and preparing it for output to a prepress system, but that is surely not the only workflow. The new technologies on the horizon (and even those that are here now) require this higher bit-depth in order to exist at all. It's not required for every workflow, but it certainly opens up the possibilities for new ones. Photoshop's support for higher bit-depths is no-doubt partly in anticipation of providing support for these new technologies as they arrive. Keep in mind that many people use Photoshop (and other imaging packages) in many different ways for many different applications.
Ken Fleisher _______________________________________________
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