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Mircula
12-07-2010, 11:56pm
Hello,

I have a question to exposure.


Lets say i expose a picture a bit to much or not just enough but nothing is clipped.

Does it has any disadvantage or image quality loss if I then play around with the exposure setting in lightroom until it is correct?

I am aware that i should always try to expose correctly, but it does not always work out and i am just wondering if that matters in any way when done in pp.


Thank you very much!

OzzieTraveller
13-07-2010, 8:42am
G'day Mircula

I presume that you mean that the histogram "looks okay, but it's a bit one-sided or off-centre"

If this is what you're referring to - it happens to many of us - comes from lots of circumstances, flat lighting etc etc. I [and most others] use Levels to slide the end-marker(s) inwards to 'kiss' the histogram and 'stretch' the image back to fill the frame. Tweaking curves will do nice things too

dunno if this helps ... :)
Regards, Phil

ricktas
13-07-2010, 8:49am
There is no such thing as a perfect historgram. There is a good article here (http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml) on understanding histograms. If you have over-exposed a photo, consider looking at converting it to mono, quite often a mono photo can deal with over-exposure better, and have quite an impact, whereas the same photo in colour just looks 'blown out'.

Zac
13-07-2010, 9:06am
If you shoot RAW at a low ISO the difference in quality is little to none.

Jpegs may suffer from posterization if adjusted too much, and noise can be an issue with high ISO images.

Mircula
13-07-2010, 11:09am
Hi,

I shoot raw and I do understand histograms. My question was just if I have any loss of quality of any kind if i stretch the image in PP. Assuming nothing is blown out.


If this is what you're referring to - it happens to many of us - comes from lots of circumstances, flat lighting etc etc. I [and most others] use Levels to slide the end-marker(s) inwards to 'kiss' the histogram and 'stretch' the image back to fill the frame. Tweaking curves will do nice things too


I assume you are referring to PS tools here? I only use Lightroom but I think in the "basic" panel i can do the same things with the exposure black etc. adjustments.

Why is noise an issue? So I do have some kind of quality loss?

ricktas
13-07-2010, 11:13am
Hi,

I shoot raw and I do understand histograms. My question was just if I have any loss of quality of any kind if i stretch the image in PP. Assuming nothing is blown out.



I assume you are referring to PS tools here? I only use Lightroom but I think in the "basic" panel i can do the same things with the exposure black etc. adjustments.

Why is noise an issue? So I do have some kind of quality loss?

If you "push" the processing you will see noise in the result. try it, over adjust a photo and see what happens at the pixel level.

maccaroneski
13-07-2010, 1:04pm
If you "push" the processing you will see noise in the result. try it, over adjust a photo and see what happens at the pixel level.

I find that too - especially if using software exposure compensation to lift an underexposed shot, even if the shadows aren't clipped.

The effect is then magnified if any other adjustments are applied, particularly those that lift sharpness and contrast.

Kym
13-07-2010, 1:21pm
My take is:
As long as your not clipping (hard right on the histogram) exposing to the right is better than to the left.

Why? More signal, less noise. Its about the way digital sensors work.

Ideally expose correctly - but when you expose to the right a little you have more to play with,
if its exposed to the left (under exposed) you have more noise issues when lifting the levels.

arthurking83
14-07-2010, 12:26am
My take is:
....

Ideally expose correctly - but when you expose to the right a little you have more to play with,
if its exposed to the left (under exposed) you have more noise issues when lifting the levels.

:th3:

the theory is that with a set of data values loitering up there on the RHS of the histogram, you have more signal and less noise to process. Excessive PPing of that image is then possible.
I've just spent the best part of a few hours describing that to another member.

My usual style is to expose with the histogram more to the left, and that's where all the colour is at! :th3: But then that leaves me no room to play PS jockey! :th3:
That's why I have to process to a very basic minimum. The only frivolity i allow myself is a very light Tonal Contrast(Tone Mapping) edit step from Nik's Colour Efex pro, where I've created my much less wild version of it and use it as a batch step.
At their settings I get crazy massive uber grain in my normal images(ie. darker more saturated stuff, but the same step works OK in the brighter(up to 1.3Ev brighter!) images(as long as the highlight as not blown).

I bracket and almost always end up using the darkest image, or sometimes the more neutral(second darkest) image. Very rarely do I use brighter of the three images.

I find that the darker images with less processing look more natural than the brighter images process back down to the same levels(where colour saturation looks nice, without looking like Ken Rockwell's "Scorched"!)

ETTR is for processing gurus! :lol:

.. I do it the other way round.

Mircula
14-07-2010, 9:51am
Cool thank you for all your comments on that.

I guess I understand it a bit better now.

Although I don't really get what you are doing in your pp steps Arthur.

What is ETTR?

Ciao.

bigdazzler
14-07-2010, 10:24am
Just remember though, dont overexpose too much. Its a lot easier to add light to a photograph than it is to recover blown bits :th3:

Mircula
14-07-2010, 10:48am
hmmm...yeah that is true. Looks terrible if some things are blown out white

bigdazzler
14-07-2010, 10:56am
Well its the old saying mate .. Expose for the highlights and let the shadows take care of themselves.

You just need to be careful underexposing for scenes that have heavy shadow detail. By lifting exposure and adding fill into darkest pixel areas, and particularly at higher ISO, you risk introducing ugly ugly noise.

Mircula
14-07-2010, 10:58am
all right.

I guess it is just a matter of being aware of all these things and shoot according...

draco
19-07-2010, 11:18pm
Well its the old saying mate .. Expose for the highlights and let the shadows take care of themselves.

You just need to be careful underexposing for scenes that have heavy shadow detail. By lifting exposure and adding fill into darkest pixel areas, and particularly at higher ISO, you risk introducing ugly ugly noise.

so shoot to the right then?

Kym
20-07-2010, 12:03am
What is ETTR?
Expose to the right ;)


so shoot to the right then?

Yes, But not so much as to have a histogram with a hard right bar.