Agreed, and as I was trying to say in my response, there are ways to automatically exclude over- and under-exposed images that add nothing to the results. I think it's the "-x" option in hdrgen, and there is a check-box in Photosphere.
-G > From: Christopher Rush <[email protected]> > Date: October 31, 2018 6:55:30 AM PDT > > Hi Clarence, > I think it is common to have better success with fewer images instead of a > full 15-image sequence. Having extra frames is probably good practice since > you might not get another chance to capture that scene, but you shouldn’t > need that many for the actual HDR creation. You mentioned trying images 6, 9, > 10, and 11 as example. The important thing would be to select images that > capture as much of the low, middle, and high exposure range as possible – > particularly important for a new camera response function. Let’s say your > image exposures are in order from darkest to brightest. Your selected > sequence should hopefully include at least one of the first few under-exposed > images – or whichever one is dark enough to have some information but no > fully white pixels. You should also include at least one of the last few > over-exposed images – hopefully one with image information but no fully black > pixels. Then pick a few of the exposures in between. You might find better > success with four or five images instead of 15. > > You might also try changing some other settings regarding automatic > alignment, ghost removal, lens flare removal, etc. if these or any other > default settings might adversely affect your specific image sequence. > > -Chris > > From: Clarence Wang [mailto:[email protected]] > Sent: Monday, October 29, 2018 10:32 PM > To: High Dynamic Range Imaging <[email protected]> > Subject: [External] [HDRI] hdrgen problems > > Hi Greg, > > I've subscribed the HDRI mailing list and the request seemed to be approved. > > For the questions mentioned before, I got failure to derive the camera > response function when running a whole set of images (1-13) in Photosphere. > Thus, I just selected 9 images in sequence (1-9) for rendering HDR image. > > However, it was confusing that I still failed to derive the camera response > function using the other sequence of images (3-11) which was successfully run > using 'hdrgen' tool and was to generate a new camera response function (the > second-order polynomial). Since you mentioned "even the same set of images > given twice won't necessarily yield the same coefficients, although they > should be close", which function or rendered HDR image is reliable? Or, can > we trust the HDR image rendered with different polynomials but well agree > with each other (almost overlap)? > > Also, If both Photosphere and hdrgen tool cannot solve response function and > fail to render a HDR image using a sequence of 15 exposed images, is it > reasonable to select less number of images (say, 6, 9, 10, 11) to yield the > HDR image and relevant camera response function using Photosphere or hdrgen > tool ? > > Thanks, > > Clarence > ____________
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