> Message: 9
> Date: Sat, 25 Jan 2003 14:28:40 -0800
> Subject: High Dynamic Range Facts...
> From: Ted Chavalas <email@hidden>
> To: email@hidden
>
> Greetings Everyone,
>
>
> I could not help writing in about this subject... We have been
> involved in this subject for several years now.
>
> While it may be fun to dream about cameras with 26F stops of dynamic
> range I must ask what will you do with them? There seems to be a lot
> of confusion about the subject.
>
> While it is true that Spheron has indeed created a camera that can
> capture these high dynamic range images... (This is NOT the only
> method for doing so.) The Spheron camera is a remarkable achievement
> and they deserve some praise for it. But take a look at the price.
> Consider that all you need to make your own high dynamic range images
> is your own camera and HDR Shop. HDR shop can be downloaded for free
> trial use.
>
> See: http://www.debevec.org/HDRShop/
>
> To make a 26F stop HDR image all you need to do is shoot 3 bracketed
> exposures and run them through HDR shop.
>
> Now what?
>
> So you have the HDR file what will you do with it? Unless you are
into
> rendering 3D scenes with high end rendering software such as Lightwave
> 3D or Radiance you probably do not have anything to open an HDR file.
> Here are some hard cold Facts:
>
> 1. Photoshop cannot open or manipulate HDR images?
> 2. QuickTime cannot open or manipulate HDR images?
> 3. Panorama Tools cannot open or manipulate HDR images?
> 4. QTVR Authoring Studio cannot open or manipulate HDR images?
> 5. VR Works cannot open or manipulate HDR images?
> 6. MakeCubic cannot open or manipulate HDR images?
> 7. Zoomify cannot open or manipulate HDR images?
>
> What will you do with your HDR image? How will you open and edit it?
>
> For most VR photographers we would want to shoot a high dynamic range
> image and then compress it down to a nice looking 24 bit image that
can
> be used with our VR players. This magic software would presumably
> lower the brightness of the windows and raise the brightness of the
> room interior to create a perfectly natural looking scene like our eye
> can see. This dynamic range compression is often called selective
> tonal mapping. We sometimes attempt it manually in Photoshop by
> shooting bright subjects, such as windows, at a different exposure and
> then compositing them into the panorama with Photoshop.
I agree with Ted that Tonemapping is not quite ready for Prime Time. But
if I were a betting man I would put my money on tonemapping; HDR
supplies much more information than any other automated exposure
compositing method. And I think I can get most panoramic photographers
to agree that we need an automated method to get more range in our
photographs whether it is using bracketed photos or higher dynamic range
cameras. Last years algorithms for tonemapping were a huge improvement
over previous attempts and I have seen a few that will be submitted for
this year's Siggraph and they are still improving.
If you are interested in playing with this you can download a plugin for
HDR Shop on website that implements one of the tonemapping algorithms
from last year Although I would still say it's not quite ready for
production use, I have combined this method with traditional exposure
compositing techniques and improved my results.
http://www.gregdowning.com/HDRI/tonemap/Reinhard/
-greg
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