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Re: [OM] IMG: More Experiments with ETTR

Subject: Re: [OM] IMG: More Experiments with ETTR
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 09 Sep 2011 03:46:10 -0700
On 9/9/2011 3:06 AM, Chuck Norcutt wrote:
> I'm currently evaluating PSE9 for a friend.  As in full PS just use the
> lasso or other selection tool to select an area.  Then press CTRL-L to
> show a histogram of that area.  Use the pull-down menu to select views
> of the individual RGB channels if desired.
>
> But being able to get a detailed view of the histogram in PS doesn't
> address my concern.

I understood. I was replying to Jim's question.

> I want to see it in-camera so I know if my current
> exposure settings will result in blown highlights.
>
> The 5D is getting pretty long-in-the-tooth as far as its small LCD
> display is concerned.  Maybe a more modern camera with 3" wide OLED will
> show me what I want to know.

I'm not so sure. The 60D is 3", although not OLED, and I don't think it's much, 
if any, better. Unless someone takes up 
your idea of enlarging the top end of the histogram, I don't think you are 
likely to find joy.

> One thing I do not like about ACR is that the histogram and intensity
> readouts do not show the headroom that is available in the raw file.
> For example, yesterday, while working on photos of dancers under
> strongly colored stage lights, the histogram and the cursor readout
> (showing 255) told me that the red channel was blown in some parts of
> the image.  Yet, since it's a raw file there was still adjustment room
> there.  Adjusting the exposure downward allowed me to get the apparently
> blown areas down to a max of 248.  I want the ACR histogram to say 262
> if there's adjustment room available.


I'm not at all certain there is a way for the program to tell that, at least 
with any accuracy. Go back to the dpr 
review of the 5D. They compare highlight recovery by  DPP, ACR and Rawshooter. 
<http://www.dpreview.com/reviews/canoneos5d/page23.asp>

You'll see that ACR is willing to go further than the others in guessing from 
context what the right value might be. My 
experience is that sometimes it's pretty amazing what it can reconstruct and 
other times doesn't do well.

I tend to watch the clipped areas of the image in ACR as I adjust Exposure and 
Recovery. If the histogram looks like 
it's recovered, but the areas that should be going to proper looking color get 
less bright, but stay neutral and don't 
develop tonal texture, it's not working and I might as well back off.

The only hope is to select those areas in PS, select other areas that have the 
colors that should be there and do Match 
Color. But when all the luminance detail is gone, even that doesn't work very 
well. If the problem area is minor in size 
or significance, getting the color right, even if there is no detail, can help 
it not stand out as troublesome.

Moose

Moose
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