Hi Jason, I assume you are assembling your images using Photosphere or hdrcvt. Unless the single exposure that doesn't over-expose the light source(s) has values very close to the maximum (255), you should be OK as far as accuracy.
The best accuracy is achieved using RAW shots and the raw2hdr Perl script that calls hdrgen, dcraw, and exiftool. This process avoids the issue of camera response by going straight from the linear CCD or CMOS sensor values. This makes more of a difference to color accuracy than luminance, but it's worth pursuing if accuracy is your goal. If you're interested in this under Mac OS X, I can post a package for you. -Greg On Tue, Jan 25, 2011 at 8:20 AM, jason huang <[email protected]> wrote: > Hi, Greetings to all in the mail list, > > I have couple questions in the context of capturing HDR environment > map for image-based lighting, and would like to hear your feedbacks. > > When capturing the HDR environment map for a scene with concentrated > light sources (say light bulb or the sun), is it correct that if the > pixel values of the light source are not saturated in the most > under-exposed bracket (but saturated throughout the rest of exposure > brackets), the full dynamic range of the light source is well > preserved? > > If I have two, three, or more under-exposed brackets presenting > non-saturated pixels for the same concentrated light source, will the > resulting HDRI be more accurate in terms of representing the > illumination of the light source during IBL than the situation where > the non-saturated pixels of the light source only present in the most > under-exposed bracket? > > Thanks, > Jason _______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
