"Exposing to the right" is over exposed, what now?
in [Photoshop]
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From: Floyd L. Davidson on 8 Oct 2009 14:36 Porte Rouge <porterougeman(a)gmail.com> wrote: >On Oct 8, 6:22�am, fl...(a)apaflo.com (Floyd L. Davidson) wrote: >> Paul Furman <pa...@-edgehill.net> wrote: >> >John Sheehy wrote: >> >> Paul Furman wrote: >> >> >>> OK, the noise is more the reason but posterizing can >> >>> be a problem in dark areas... >> >> The only cameras I know of with even a hint of RAW >> >> posterization are the Pentax K10D, which would profit >> >> from 13 bits instead of 12 at ISO 100 (not for 200 or >> >> higher), the Sony A900 also with a need for 13 bits at >> >> base, and the D3X when in 12-bit mode. �These are only >> >> on the fringe of posterizing. >> >> >>> raising shadows in post for the deepest shadows, and >> >>> in skies where the color pallet is very >> >>> limited. Doesn't the noise level follow this same >> >>> principle? Or is there an unrelated reason for the >> >>> noise levels paralleling tone counts? >> >> Any posterization you see in a RAW conversion is most >> >> likely caused by the math used in the converter, and >> >> nothing else. �Of course, JPEG compression does some >> >> posterization of its own, especially if you use too >> >> much NR and it starts blocking up. >> >> >OK, this makes sense, the posterizing issue is not really visible in any >> >sort of normal exposure. What about Floyd's comment below that the noise >> >level remains the same but exposing to the right increases the signal so >> >that overwhelms the noise? That seems to tie the two together in a >> >comprehensible way. The LL link just makes a lot of sense, it can't be >> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.shtml >> >> That is an *excellent* article. �It also has a link to >> another article, titled "Understanding Histograms", >> which several contributors to this thread could benefit >> from (particularly the histogram of the moon shot and >> the high key tree image that are the last two shown at >> the bottom of the article): >> >> �http://www.luminous-landscape.com/tutorials/understanding-series/unde... >> >> -- >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> >> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...(a)apaflo.com > >Hey, that's the same article you said this about: > >"But regardless of that, the cited URL above from >luminous-landscape is *not* full of good stuff. They >miss the point entirely, and provide nothing that is >actually useful!" No it is *not* the same article. -- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd(a)apaflo.com
From: Porte Rouge on 8 Oct 2009 14:46 On Oct 8, 2:36 pm, fl...(a)apaflo.com (Floyd L. Davidson) wrote: > Porte Rouge <porterouge...(a)gmail.com> wrote: > >On Oct 8, 6:22 am, fl...(a)apaflo.com (Floyd L. Davidson) wrote: > >> Paul Furman <pa...@-edgehill.net> wrote: > >> >John Sheehy wrote: > >> >> Paul Furman wrote: > > >> >>> OK, the noise is more the reason but posterizing can > >> >>> be a problem in dark areas... > >> >> The only cameras I know of with even a hint of RAW > >> >> posterization are the Pentax K10D, which would profit > >> >> from 13 bits instead of 12 at ISO 100 (not for 200 or > >> >> higher), the Sony A900 also with a need for 13 bits at > >> >> base, and the D3X when in 12-bit mode. These are only > >> >> on the fringe of posterizing. > > >> >>> raising shadows in post for the deepest shadows, and > >> >>> in skies where the color pallet is very > >> >>> limited. Doesn't the noise level follow this same > >> >>> principle? Or is there an unrelated reason for the > >> >>> noise levels paralleling tone counts? > >> >> Any posterization you see in a RAW conversion is most > >> >> likely caused by the math used in the converter, and > >> >> nothing else. Of course, JPEG compression does some > >> >> posterization of its own, especially if you use too > >> >> much NR and it starts blocking up. > > >> >OK, this makes sense, the posterizing issue is not really visible in any > >> >sort of normal exposure. What about Floyd's comment below that the noise > >> >level remains the same but exposing to the right increases the signal so > >> >that overwhelms the noise? That seems to tie the two together in a > >> >comprehensible way. The LL link just makes a lot of sense, it can't be > >> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.shtml > > >> That is an *excellent* article. It also has a link to > >> another article, titled "Understanding Histograms", > >> which several contributors to this thread could benefit > >> from (particularly the histogram of the moon shot and > >> the high key tree image that are the last two shown at > >> the bottom of the article): > > >> http://www.luminous-landscape.com/tutorials/understanding-series/unde... > > >> -- > >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> > >> Ukpeagvik (Barrow, Alaska) fl...(a)apaflo.com > > >Hey, that's the same article you said this about: > > >"But regardless of that, the cited URL above from > >luminous-landscape is *not* full of good stuff. They > >miss the point entirely, and provide nothing that is > >actually useful!" > > No it is *not* the same article. > > -- > Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> > Ukpeagvik (Barrow, Alaska) fl...(a)apaflo.com This is the link in both of Paul's posts: http://www.luminous-landscape.com/tutorials/expose-right.shtml
From: Floyd L. Davidson on 8 Oct 2009 15:04 Porte Rouge <porterougeman(a)gmail.com> wrote: >On Oct 8, 2:36�pm, fl...(a)apaflo.com (Floyd L. Davidson) wrote: >> Porte Rouge <porterouge...(a)gmail.com> wrote: >> >On Oct 8, 6:22�am, fl...(a)apaflo.com (Floyd L. Davidson) wrote: >> >> Paul Furman <pa...@-edgehill.net> wrote: >> >> >John Sheehy wrote: >> >> >> Paul Furman wrote: >> >> >> >>> OK, the noise is more the reason but posterizing can >> >> >>> be a problem in dark areas... >> >> >> The only cameras I know of with even a hint of RAW >> >> >> posterization are the Pentax K10D, which would profit >> >> >> from 13 bits instead of 12 at ISO 100 (not for 200 or >> >> >> higher), the Sony A900 also with a need for 13 bits at >> >> >> base, and the D3X when in 12-bit mode. �These are only >> >> >> on the fringe of posterizing. >> >> >> >>> raising shadows in post for the deepest shadows, and >> >> >>> in skies where the color pallet is very >> >> >>> limited. Doesn't the noise level follow this same >> >> >>> principle? Or is there an unrelated reason for the >> >> >>> noise levels paralleling tone counts? >> >> >> Any posterization you see in a RAW conversion is most >> >> >> likely caused by the math used in the converter, and >> >> >> nothing else. �Of course, JPEG compression does some >> >> >> posterization of its own, especially if you use too >> >> >> much NR and it starts blocking up. >> >> >> >OK, this makes sense, the posterizing issue is not really visible in any >> >> >sort of normal exposure. What about Floyd's comment below that the noise >> >> >level remains the same but exposing to the right increases the signal so >> >> >that overwhelms the noise? That seems to tie the two together in a >> >> >comprehensible way. The LL link just makes a lot of sense, it can't be >> >> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.shtml >> >> >> That is an *excellent* article. �It also has a link to >> >> another article, titled "Understanding Histograms", >> >> which several contributors to this thread could benefit >> >> from (particularly the histogram of the moon shot and >> >> the high key tree image that are the last two shown at >> >> the bottom of the article): >> >> >> �http://www.luminous-landscape.com/tutorials/understanding-series/unde... >> >> >> -- >> >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> >> >> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...(a)apaflo.com >> >> >Hey, that's the same article you said this about: >> >> >"But regardless of that, the cited URL above from >> >luminous-landscape is *not* full of good stuff. �They >> >miss the point entirely, and provide nothing that is >> >actually useful!" >> >> No it is *not* the same article. >> >> -- >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> >> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...(a)apaflo.com > >This is the link in both of Paul's posts: > >http://www.luminous-landscape.com/tutorials/expose-right.shtml The article I made that comment about is entirely different. It is by Ray Maxwell and is titled "A Possible Problem with Expose to the Right! Or Settings for an Accurate Histogram". Here is a direct quote from the article I posted, showing a distinctly different URL than the one above: ">>> http://www.luminous-landscape.com/tutorials/right-hista.shtml >> Wow, good stuff. I had to run out and get my camera >> and check the ... But regardless of that, the cited URL above from luminous-landscape is *not* full of good stuff. They" Message-ID: <87my45th9g.fld(a)apaflo.com> Date: Mon, 05 Oct 2009 17:58:51 -0800 -- Note that I am not using my usual signature on this article, because you have quoted it along with the body of text in every single exchange, which is ridiculous!
From: John McWilliams on 8 Oct 2009 17:14 Clues wrote: > On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy <JPS(a)no.komm> wrote: > >> Exposure to the right is usually given as advice for RAW shooting. The >> RAW data usually clips well above the level where a JPEG would clip it, > > Very true, for all those cameras that intentionally do a poor job at the > RAW to JPG conversion. This is why RAW became so popular. DSLRs are > inherently poor at this process. In fact it's the very reason that having > access to the RAW data became so popular. Far too many DSLR owners wanted > to repair in their resulting images what the DSLR's firmware programmers > failed to do correctly in the first place. Companies then realized that > they could turn this into an asset. Not only sell a camera that didn't work > quite right, bundled with a kit-lens that wouldn't provide images any > better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to > make their $500 DSLR functional, but now also sell them expensive editing > software to fix what their cameras weren't doing properly to provide a > useful image right out of the box. 'Ceptin' the major camera mfg's provide software with the purchaseof the camera, and excellent lenses can be had for a mere grand. One or two {Nikon} may also try to sell "Pro" RAW converters. Most in-camera conversion for JPEGs is above very decent, and is excellent for daylight/time normal exposures. -- john mcwilliams
From: Floyd L. Davidson on 8 Oct 2009 23:07
Doug McDonald <mcdonald(a)scs.uiuc.edu.remove.invalid> wrote: >I have performed tests on my Canon 30D camera to see >what happens if I expose less. I exposed 1/3 and 2/3 >stops less than before. > >At 2/3 stop less than before yes, even at contrast setting zero, >I do see a teensy bit of space between the top of the red histogram >and the top of the display. This means that if I'm willing to >lose 2/3 stop of unclipped data at the bright end, Floyd is "effectively" >right. > >But if I want that extra 2/3 stop, I'm still correct. You have verified that you can't read a histogram, and that what I've previously said is true. Changing contrast isn't helping you a bit, but WB adjustment would make your histogram more accurate, as well as make your preview JPEG image greenish. Your description suggests that at 0 EC your histogram was indicating you should be clipping. The red channel though, due to WB adjustment, is typcially about 1/2 to 3/4 of an fstop higher in the JPEG than it is in the raw data. (Look in the Exif data and to find out what the red channel multiplier is, and you can calculate exactly what the fstop value differential is.) To *correct* the inaccuracy of your histogram you can adjust the WB to be more greenish. That will reduce the red channel in the JPEG to agree with the raw data. Changing contrast does *not* change the histogram's representation of exposure, and therefore *cannot* make the histogram more accurate. Only WB adjustment will do that for you. >I should add that my method works --- I use -4 in the camera, >use the histogram, and find my raw images are very nicely exposed, >no clipping (except as desired for specular highlights) and the >data right up to the clipping level. All you are doing is misunderstanding the histogram, and because the WB adjustment gives you 1/2 to 3/4 of an fstop of leeway, you end up with useful results. It is very unlikely that you have the technical expertize to even determine how close your raw data is to clipping, never mind being able to see any difference in losing that amount of dynamic range at the low end of the exposure range as a result of the inaccurate histogram. -- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd(a)apaflo.com |