Thanks Rogier, I think I must study more those details of image formats. These information you told us have clarified my mind a little more. Do you recommend a good general reference about it?
And you are right, I fix the exposure bracketing for the whole panorama and as I use a manual workflow in hugin I just don't do exposure optimization. To tell more details of my usual exposition workflow, I use Magic Lantern firmware on my canons, so I have a more flexible control of auto bracketing. I usually do expositions with 2EV of difference between pictures and choose, experimenting on the scene, if I need 3, 4 or 5 different expositions. Magic Lantern allow me to use up to 9 auto bracketing pics. I also define the order. I usually set it to make the darker one first, then it goes increasing the exposition time, giving me more clear pics. Due to that I first measure the light on the most clear area of the scene. This setup will make the first picture, the darker one. Then I test the pictures in the most dark area and take a fast look at the pictures to decide how many brackets are ok. I never needed more than 5 until now, using 2EV between them. I usually think using less than 2EV this is useless. Have already tried, for example, 3 pics with 1EV between them and it really didn't expand the dynamic range. Maybe I should try something like 9 pics with 1EV dif and compare with 5 pics with 2EV dif. Anyway, with this I do the workflow I mentioned before, in which, again, I don't make any exposure correction in hugin and I think I get some good results, which can be seen in my blog. Here is one example where I have used 4 auto bracketing pics with 3EV between them - total of 12EV of difference from the first to the last: http://wp.me/p1AGa0-hp Cheers, Carlos E G Carvalho (Cartola) http://cartola.org/360 http://www.panoforum.com.br/ 2012/11/19 Rogier Wolff <[email protected]> > > Guys, > > when you say "24 bit jpeg" almost everybody thinks of this as "full > color (RGB), 8 bits per channel". > > What is needed for HDR work, is either a floating point format (about > 12 bits per channel, would be sufficient, but 32 bits per channel are > normally used in hugin) or a high-bit-count fixed-point > format. Something like 16 might get close, but 24 bits per channel. > may be more appropriate. > > JPEG format is not appropriate for non-8-bit-per-channel-data. So > Carlos in the workflow that you describe you're truncating a lot of > information when you output your intermediate files into the 8-bit > jpeg format. > > So... Carlos, I would suggest that you try saving your intermediate > files as tiff, and then find out what options you have to create a > 32-bit-per-channel-floating-point intermediate file. Then Hugin can, > while stitching, apply proper exposure corrections and things like > that. (or are you fixing the exposure bracket for the whole panorama? > In that case Hugin's exposure correction should be unneccessary.) > > > Roger. > > On Mon, Nov 19, 2012 at 08:35:41AM -0200, Carlos Eduardo G. Carvalho > (Cartola) wrote: > > Hi, > > > > just to clarify, I don't work with 24-bit jpg. I usually shoot in JPG and > > work with it in 8 bits. But alit_image_stack can deal with tif and you > can > > work with tif all the time. I just put JPG in my example because I use > it :) > > > > I sometimes have some ghosts in the final result of the enfusion, but I > > doubt if it would solve using a larger image. I think they happen because > > of parallax differences. I can clearly see that part of the image is good > > and another is not, so I think align_image_stack has done it's job. The > > solution (maybe) would be distort the image before fuse them and maybe > > hugin does that, I don't know. In fact I have never tried to make the > > exposure stacks directly into hugin. Maybe I should also give it a try :) > > > > And surely the best option of all is to stabilize the camera to shoot, > but > > sometimes it is a little hard to do: > > > http://cartola.org/fotos/_cache/Diversas/Engenhocas/_screen/20111004-mastro.jpg > > > > Cheers, > > > > Carlos E G Carvalho (Cartola) > > http://cartola.org/360 > > http://www.panoforum.com.br/ > > > > > > > > 2012/11/18 TvE <[email protected]> > > > > > Carlos, thanks for posting your steps. Running align_image_stack from > the > > > command line sounds like a nice idea. You could also output the result > into > > > the .pto file, I believe. I don't know about pre-fusing each stack > into a > > > 24-bit jpg. I would be concerned that you could end up with images that > > > have very different dynamic ranges and that don't blend well into the > final > > > pano. E.g. if one stack has sunset-to-dark and the other is all-dark. > But > > > maybe enfuse deals with that properly or maybe those scenarios don't > fuse > > > well either way... If I have the time I may give the two approaches a > spin. > > > Another advantage of not pre-fusing is that align_image_stack > sometimes has > > > difficulties, specially when large areas are very dark or blown out in > one > > > of the images of the bracket and it's nice to be able to adjust the > control > > > points in hugin. Ah. maybe we can collect some more wisdom and then > turn > > > this thread into a wiki page. > > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Hugin and other free panoramic software" group. > > > A list of frequently asked questions is available at: > > > http://wiki.panotools.org/Hugin_FAQ > > > To post to this group, send email to [email protected] > > > To unsubscribe from this group, send email to > > > [email protected] > > > For more options, visit this group at > > > http://groups.google.com/group/hugin-ptx > > > > > > > -- > > You received this message because you are subscribed to the Google > Groups "Hugin and other free panoramic software" group. > > A list of frequently asked questions is available at: > http://wiki.panotools.org/Hugin_FAQ > > To post to this group, send email to [email protected] > > To unsubscribe from this group, send email to > [email protected] > > For more options, visit this group at > http://groups.google.com/group/hugin-ptx > > -- > ** [email protected] ** http://www.BitWizard.nl/ ** +31-15-2600998 ** > ** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233 ** > *-- BitWizard writes Linux device drivers for any device you may have! --* > The plan was simple, like my brother-in-law Phil. But unlike > Phil, this plan just might work. > > -- > You received this message because you are subscribed to the Google Groups > "Hugin and other free panoramic software" group. > A list of frequently asked questions is available at: > http://wiki.panotools.org/Hugin_FAQ > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/hugin-ptx > -- You received this message because you are subscribed to the Google Groups "Hugin and other free panoramic software" group. 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