Tone equalizer vs tone curves

To me the whole video was sort of a miss because he mistakes TE for being a 1:1 replacement for the other tools. It is not. Filmic sets the upper and lower bounds, something he does in tone curve by dragging in the points, then tries to do with TE, and sort of does, but TE works a lot better with filmic enabled.

Also note that he had a relatively flat and desaturated scene, and didn’t at all bother to set a color picker point and see what actually happened with a measurement. He eyeballed it and said “well close enough” and sure, you could probably get away with any of the three with an image like he uses.

Note that o was hard pressed to give up the LAB tone curve as well. I know it, I’m comfortable with it, I understand the way it works. But Filmic + TE is easier.I have old edits where the file is flat that I needed to use two masked tone curves to get it right. Filmic and TE let me add enough contrast that multiple modules aren’t necessary.

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Mainly depends on how you set your exposure.

I use tone equalizer before (underneath) exposure to tame the highlights in extreme cases. 0ev is then always your highest white point, since almost nothing has been done to the data yet.

But normally I do what most others do : activate it (let it sit in the pipeline where it sits itself by default), go to the advanced tab, and then hover your mouse over parts of the image you want to make brighter or darker, and give little nudges with the scroll wheel.
I don’t care what the values are reading, I just hover and scroll without looking at the tool.

Almost always this is used to make a darker part a bit brighter if filmic crushes it too much.

If filmics output is too flat I can also use one of the tone curve presets inside TE to give some contrast. Although then I always change the 0ev part (in simple or advanced) to be back at 0, so to not change the highlights that I have set already.
I do this if the image is too flat but I don’t want to mess with local contrast too much (faces / portraits for example).

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And always the big benefit of the modern tools is that it doesn’t destroy all the highlight data that is there but is too bright to be visible.

I think a normal old curve tool will destroy everything over 1.0 before filmic has a chance to map it.

If you use them after (above) filmic it’s OK, but for me you might as well use TE.

I also like that it starts as a flat horizontal line instead of a diagonal line up. I know this is against the convention, but for making adjustments it makes more sense to me. Easier to see what is happening at every point (making it brighter or darker).

And apparently it’s better at preserving the correct chromatic representation when the brightness changes, but my adjustments have never been too strong to notice that.

I wrote a long description here, but realised that the best explanation is: darktable 3.0 : dodging and burning with the tone equalizer - YouTube

Anyway, I won’t delete it:
When you use tone equalizer in any of the preserve details modes, it’ll blur the image to create a mask; you then use the various controls under mask post-processing to get it (the brightness of the mask) to fit into that 8 EV range. The use of the mask guarantees that pixels in an area (unless separated by an edge) are treated the same way: the same adjustment, defined by the brightness of the mask covering them and the adjustment you set for that mask brightness level, will be applied, thus local contrast (the relative brightness of pixels) is maintained.

Suppose you want to compress the dynamic range (reduce global contrast) a bit. This could be done with an inverse S curve: you’d lower highlights and raise shadows. If you apply that curve without detail preservation (that is, on a pixel-by-pixel basis), a bright and a dark pixel next to each-other will end up with less of a difference → local contrast is lost. With preserve details, if the area containing those pixels is dark, both pixels will be brightened; if it’s bright, both will be darkened. That way, global contrast is reduced (brighter areas become less bright, darker areas become less dark), but local contrast (the bright pixel’s brightness compared to its dark neighbour) is maintaned.

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I sometime let it go one way or the other and use 2 instances and focus one on highlights and one on darker tones…at least for a complicated image as then you target those areas in the one instance and not try to fix everything with one…

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I have experienced this many times.
I tweak the sliders to make the grey bar under “mask post-processing” cover much of the shown interval but the histogram under the advanced tab turns afterwards out to have turned very flat like in your example.
Can anyone explain why this is happening and how to avoid this situation or systematically change the settings so that the histogram (and mask) becomes useful?

For myself, I depend on the Tone Equalizer just about always.

The big difference between the tone/base curve and the tone equalizer is that the former are tonal adjustments, while the latter is a spacial change.

The curves affect all pixels of a particular brightness the very same way. The equalizer segments the image into areas, then changes exposure smoothly in these areas.

Say you reduced highlights and lifted shadows. With the curve, this will reduce contrast in every part of the image. With the EQ, contrast within each region will remain unchanged, but the overall dynamic range is reduced. This looks more natural in most images.

The downside is, the tone EQ can produce subtle halos if pushed too far. Look for them in the little preview at the top left of the screen. They can be hard to spot in the full-screen view. (And the halos are much better-behaved than e.g. Lightroom’s Shadows and Highlights slider).

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…and the halos can be reduced by adjusting ‘smoothing diameter’ and ‘edges refinement’ in masking, at the expense of local contrast. It gives you the choice of having your cake or eating it…

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It took me a while to realize this but those presets are very useful. Different image conditions combined with different presets (and the options for “preserve details”) can either make an image work or be super frustrating.

I’d say, if one is finding an the TE difficult to work with, just go down the list and see how the image looks with every preset. At least one of them should bring a good result.

Screenshot_20210913_141445

Often, just the “simple tone curve” works for most images, with preserve details set to no. Other images that have some dramatic dynamic range differences perhaps need the other presets.

Screenshot_20210913_143205

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Note that detail preservation is more important for the cases when you reduce contrast: when you increase it, details are preserved (enhanced) by definition: increasing global contrast translates into increasing local contrast, too.

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Maybe naive from my point, but what do you consider useful?
I never needed a histogram for the tone equalizer, and I can’t see (yet) what that would bring?

The histogram is displayed whenever you use the advanced option to adjust your image. If the histogram is completely flat then your settings under the masking option are not “useful”.

My question was ‘what do you use the histogram for when using some sort of curve adjustment’… What point is a histogram for you in a curve adjustment?

You check the histogram of the blurred mask to make sure it covers the 0…-8 EV range as well as possible, so you can make changes to each brightness range separately.
image

If the histogram shows a narrow band, say, -5 to -3 EV, you won’t be able to make fine changes, as dragging the -3 EV point also drags along -4 EV and, to a lesser extent, -5 EV, to guarantee smoothness.
image

On the other hand, of the histogram shows that many values are over 0 EV or below -8 EV, you won’t be able to make direct adjustments for those; for everything above 0 EV, the setting of the 0 EV ‘band’ is used, and the situation is similar for those below -8 EV.
image

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The histogram is for the mask, not the image, just in case that wasn’t clear from @kofa’s good post above. It’s essential to know your control points will act on the areas you want.

I have been using masks to split the effects of tone equalizer on sky vs foreground, water, etc. Happy with the increase in control but wondering if there is a way to match the exposure range to the UI graph (scale up) to improve sensitivity.

Much of the graph seems to be “dead space”. The luminance bars only extend over a portion - as if they represent the range of the full image rather than the mask.

Thanks for pointing me in the right direction. I figured it out - the “small print” stuff under “masking”. Perfect.

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lots of good tips in this thread, now that I took the time to read through it