Levels Tutorial

[lourdes]

Thanks Rick, good tut.

[Miaow]

Thanks for this Rick, Great tutorial

[draco]

very nice tutorial.. easy to read, easy to understand.. thanks Rick

[nouveau1]

Couldn't find an answer to this one in the thread, so forgive me if someone has already answered this, but...
Doing the RAW work (in my case in Canon DPP) obviously alters the histogram when one comes to look at it in the RGB. What are the advantages/disadvantages of manipulating the images in the two different ways?
Any info appreciated..

[ricktas]

Any alteration to your photo is going to adjust the histogram. I am not sure what you mean by the two different ways?

[nouveau1]

thanks for reply..

I may have misunderstood something here as I think(???) the histogram I'm seeing in the DPP raw tab might actually be a luminance histogram, not a levels one. I guess (?) this would make sense as this histogram can be used to manipulate over/underexposure by shifting the whole curve (+/- 2 EVs), not sliding the dark or light levels as in your tute (which I incidentally found very useful).

I'm not explaining this very well, I clearly don't understand it well enough yet.

Thanks

[ricktas]

AH, yes there are several ways to change histograms and differing software allows differing changes. You maybe comparing the photoshop curves adjustment, with the levels one. I reckon your DPP software has something like curves adjustment as well.

[nouveau1]

i forgot to complete the thought (?dementing); so, the questions i'm asking become;
1/ what are the advantages/disadvantages to manipulating exposure using the raw luminance histogram vs the RGB one?
2/ are there other useful things one can do with the luminance one (IF that's what it is) in RAW?

[ricktas]

I am not familiar with DPP so maybe someone else can answer that one.

[nouveau1]

thanks anyway! i'm learning heaps from your site..

[jev]

1/ what are the advantages/disadvantages to manipulating exposure using the raw luminance histogram vs the RGB one?

The raw luminance histogram allows you to manipulate the dynamic range of the image (compare it to the "levels" tool in other software) - it mainly allows you to set black and white point. There is no gamma manipulation possible, but you can do some contrast adjustments. Note that this histogram is not linear, it is logarithmic!

You ask about exposure - always adjust that in the raw luminance tool because that allows editing at the full dynamic range.

The RGB histogram takes the output of the RAW processing step and manipulates that in terms of output range. It works more like the curves tool in other software.

[nouveau1]

The raw luminance histogram allows you to manipulate the dynamic range of the image (compare it to the "levels" tool in other software) - it mainly allows you to set black and white point. There is no gamma manipulation possible, but you can do some contrast adjustments. Note that this histogram is not linear, it is logarithmic!

You ask about exposure - always adjust that in the raw luminance tool because that allows editing at the full dynamic range.

The RGB histogram takes the output of the RAW processing step and manipulates that in terms of output range. It works more like the curves tool in other software.

Just read this today and do appreciate reply. I have been mucking around (DPP) with an image with high dynamic range and wonder, if you have the inclination, would you be willing to comment if I posted them? - just 3 images; the original from the raw into jpeg, a raw luminance adjusted and then a 3rd using RGB curves/levels (DPP again). It may help me (?other newbies too) understand the software possibilities a little better...

cheers, rick

[ricktas]

Rick, you would need to post them into member photos area, for critique. The tutorials area is not a place for photo reviews. So post them in the relevant photo area stating what you want feedback on etc, and you will get it.

[etherial]

I think I know what Rick (nouveau1) is getting at here, as I think I have the same question.

It appears to me that these levels adjustments are very similar to what you might do with Adobe Camera Raw with a raw image? (Or any other raw image tool for that matter)? DPP is similar in that you can drag the edges of the histogram in and ACR uses the numerous sliders to do effectively the same thing. They all just have subtly different terminology or ways of displaying these controls.

Am I right?

[ricktas]

Yes Mic. Levels adjustments can be performed in DPP, Camera Raw, Lightroom, Aperture, Picasa, Gimp, etc etc. They all work similarly, but may have different icons etc for the various functions and the nomenclature for those functions may also differ.

[etherial]

Ok so I'm on the right track. Would it be safe to saw where possible do your levels adjustments in the raw form and if all you have is jpg or tiff, use PS and the method above?

Now then, curves is another story yes? ACR can't do curves other than some minor adjustments with saturation etc. Whereas PS can do curves adjustments with much more flexibility yes?

(DPP has another tab for doing curves adjustments which could account for the confusion earlier in this thread).

Curves I have no idea...I look forward to that tute when you get the time!

Cheers,

[ricktas]

I tend to do a general check of the histogram in my RAW software(Lightroom) and occasionally make adjustments at that point. Ultimately it is about getting the exposure right in-camera, well as right as you can, and then work wit it in the editing software of your choice. All the adjustments and changes you make to your photo while editing it in PS or similar can affect the histogram, so it can be worthwhile re-checking your histogram (and levels) towards the end of your work-flow as well.

[Chilli]

Just to add to Ricks excellent tute, Using CS3 if you hold the alt key while adjusting the black/white sliders your photo will go either black or white and you can see the detail beginning to appear as you move the sliders.....cool

Thanks for this tutorial Rick and thanks for this amazing tip dbax.....wowww !

[Elvie]

Thanks Rick, that helpful advice is very much appreciated. Elvie

[mish13]

Thank you everything is starting to make sense to me now.