Now I full agree with you :)
2010/9/18 Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
> Your confusion stems from the two of us having different definitions of
> proper exposure. You accept that it may be necessary to "underexpose"
> to keep the highlights from being blown. I assert that a proper
> exposure is one that does not blow the highlights. That exposure is the
> correct exposure, not one that is "underexposed".
>
> The problem, of course, is that the dynamic range of the scene may
> exceed the capability of the camera to record without clipping on one
> end or the other. If you shoot JPEG only, the 10 stop dynamic range you
> mention below cannot be contained within a JPEG which has, theoretically
> at least, an 8 stop range. But with proper exposure the 10 stop dynamic
> range may be captured in raw (with a sufficient number of bits) without
> blowing either the highlights or the shadows. But in the end the
> dynamic range must be reduced to that on a JPEG and eventually to that
> of a print (about 5 stops). I you shoot raw with a good camera you can
> capture the 10 stop range and then be in control of how the range is
> reduced to JPEGs and prints.
>
> see: <http://www.luminous-landscape.com/tutorials/expose-right.shtml>
>
> Chuck Norcutt
>
>
> On 9/17/2010 10:55 PM, David Irisarri wrote:
> > Dear Chuck,
> >
> > I would be very pleased if you could explain to me this again as I don´t
> > really understand you very well.
> >
> > I agree with Ken. If you have 7 stops of shadow detail and 3 stops of
> > highlight detail, I would definitely expose for the highlights despite of
> > the image will be underexposed, otherwise you´ll never recover the burnt
> > highlight detail. So the camera underexposes to keep highlight detail
> inside
> > the dynamic range. This is why I would be very pleased if you could
> explain
> > to me what you mean because the other way round isn´t true.
> > What do I mean with underexpose? After taking the picture, if I see a
> > straight line going up in the right part of the TFT screen (histogram), I
> > must underexpose the picture because I know highlights will be
> > unrecoverable.
> > I never had any trouble increasing exposure by 1 to 1.5 stops with my E-1
> at
> > ISO 100. No posterization at all was seen. I only see posterization with
> > PhaseONE C1 because uses 3D LUT ICC profiles and in these cases you can
> see
> > posterization!!! because 3D lut ICC profiles haven´t got the precision of
> > matrix ICC profiles.
> >
> > Dave
> >
> >
> >
> >
> >
> > Olympus E-1. 7
> >
> > 2010/9/17 Chuck Norcutt<chucknorcutt@xxxxxxxxxxxxxxxx>
> >
> >> From your comment on the E-1 dynamic range test:
> >> "Now, for the opposite end of the spectrum. The Olympus E-1 sacrifices
> >> the highlights for preservation of the shadows. This is different than
> >> the Canon cameras which sacrifice the shadows for preservation of the
> >> highlights. Where "Expose-to-the-Right" is a recommended procedure for
> >> the Canons, exposing for the midtones or even the shadows is recommended
> >> for the E-1."
> >>
> >> Me thinks you don't really understand "expose to the right". It has
> >> nothing to do with sacrificing the shadows for the highlights or
> >> vice-versa. It's intended to avoid sacrificing anything. It's based
> >> strictly on the characteristics of the binary representation of the
> >> brightness of a pixel. Increasing the brightness level of any pixel
> >> (regardless of the camera that produced it) has a tendency to create
> >> posterization due to the multiplication and then integer rounding of
> >> small binary numbers. Decreasing the brightness has no such effect.
> >> Therefore if the exposure is not perfect it is better that it be
> >> overexposed and reduced in brightnes in post processing as long as the
> >> highlights are not blown.
> >>
> >> For example: I have 3 pixels with brightness 10, 11, 12. I increase
> >> their brightness by one stop by multiplying by the square root of 2 =
> >> 1.4142 which yields (after rounding) 14, 16, 17. But reducing the
> >> brightness of overexposed pixels 245, 246, 247 by dividing by the square
> >> root of 2 yields (after rounding) 173, 174, 174. After dividing down I
> >> end up losing some tonal information by creating two pixels of the same
> >> value but I have not created any tonality "holes" as in the jump from 14
> >> to 16 above.
> >>
> >> Chris posted a photo the other day that showed exactly this problem.
> >> The histogram of his image showed a lot of spikes and holes caused by
> >> brightness manipulation. This is also why you want to do any image
> >> editing in 16 bits even if the original image is an 8 bit JPEG.
> >>
> >> Chuck Norcutt
> >>
> >>
> >> On 9/17/2010 6:19 PM, Ken Norton wrote:
> >>>> Yeah! Let´s do it and show the charts to everyone. It took me too many
> >> hours
> >>>> to generate them. Norman Koren (The Imatest programmer) told me he was
> >>>> amazed with KODAK KAF-5101 sensor!
> >>>> Shadow information is awesome. Yeah!!! Highlight EV is very narrow. I
> >> think
> >>>> is the reason why E-1 underexposes.
> >>>> I am pretty sure many people thinks E-3 had wider dynamic range
> compared
> >> to
> >>>> E-1. :)
> >>>
> >>> LOL, not in my tests! The E-1 gives what appears to be at least one,
> >>> if not two stops more recoverable shadow detail than the E-3. I
> >>> regularily underexpose by a full stop and have to pull it up in
> >>> conversion. Not a problem at all. There are few cameras you can do
> >>> that with and still keep your sanity. Noise? Well, no E-1 image is
> >>> clean at any brightness level anyway, so it's not much of an issue.
> >>>
> >>> I think I adequately proved this point with this test:
> >>>
> >>>
> >>
> http://zone-10.com/cmsm/index.php?option=com_content&task=view&id=493&Itemid=1
> >>>
> >>> AG
> >> --
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> >>
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