Olympus-OM
[Top] [All Lists]

Re: [OM] IMGS: Baracoa, + Banding?

Subject: Re: [OM] IMGS: Baracoa, + Banding?
From: Moose <olymoose@xxxxxxxxx>
Date: Tue, 19 May 2015 22:00:14 -0700
I promised (threatened?) to post illustrative examples. 
<http://www.moosemystic.net/Gallery/Others/Manley/LNP.htm>

The heart of my point is in the second image:

1. Lower left histogram is of the original image out of the camera.

2. I've arbitrarily raised the 'exposure' to something like I imagine would be good for the procedure I proposed. I'm not saying it's perfect, certainly not that it's what you would want after post. Upper left histogram shows what happens when you pull up the shadows. See all those spikes, separated by blank space? That's what happens when shadows down too far, where there are very few digital values to assign the analog input into. When pulled up, you have only a few, discrete, widely separated brightness values. So of course you get banding. Something with nuanced, continually varying brightness is broken into separate areas of only a few brightnesses.

There's also some stacking in the upper mid tones, which will also mess with tonality. Light enough that one won't tend to see what's wrong, without looking at the histogram, but may sense something 'off'.

3. The lower right histogram is of a normal, daylight scenic, nicely balanced.

4. The upper right histogram is #3, pulled deeply down. You can see the similarity of the lowest part to #1. BUT, there are no gaps or stacks, so no banding or other artifacts from making it much darker.

I believe if you had shot at ISO 1600, then pulled down (after NR), rather than 320 and pulling shadows up, the end result would be superior; and no banding.

Version four is a simple application of the PS ShadowHighlight tool, which I think gives better results than the first version you posted. The couple in that version are good, but all the highlights are gray. Real lights don't have gray centers, drifting toward white at the edges, and the brightly lit front of the building and vendor's T-shirt have gone all gray.

Even in this mild opening up of shadows, you can see the effect of shooting too dark showing up as stacks in the histogram, but not visible.

HistoMoose

On 5/11/2015 8:43 PM, Moose wrote:
On 5/11/2015 2:52 PM, Tina Manley wrote:
Thanks, Moose.  The original dng does not look terribly underexposed.  I
can still see details in the shadows. Here it is:

http://www.pbase.com/tinamanley/image/160035214

You are confusing technical exposure to viewing exposure, to coin an awkward 
phrase.

What you have is an exposure good for viewing right out of the camera, but that pushes the limits of the sensor system. What I proposed is an overexposure corrected in post for viewing, one that lets the sensor system work better.

Any more exposure and there would be even more totally blown out.

I think only the bright lights, which are gone anyway. Remember, the overly bright building facade, etc. come back down in post.

I've always resisted using higher ISOs but I guess I'll try and see if it makes 
a difference.

Why? Even at ISO 3200, it's not as noisy as many of your great film shots in 
the dark are grainy. :-)

I'm still not sure why you care about the banding, as it can apparently only be seen when the deep shadows are raised up to very unnatural levels.

I need to get off this list madness and get ready to leave on a little trip tomorrow, or I would do some illustrations. Maybe later.

Travelin' Moose



--
What if the Hokey Pokey *IS* what it's all about?
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz