If you’ve never driven a standard transmission, it’s possible you’ve wondered why anyone would bother with a car that involves extra work to drive. Sure, you look cool doing it… But seriously, foot-hand coordination? Why?

One word: Control. The Tone Curves tool is like the stick shift of photo light and color adjustments. Yes, you can use lighting and exposure tools, but Tone Curves gives you a whole other level of control over the tonal range. You can select specific colors, (red, blue, or green), to adjust, or the entire range of the image. And then still adjust lighting and exposure after and beyond to get the image just how you like it.

Let us first look at adjusting contrast and learn how the tool works. Begin with an image in Edit mode (or Develop for non-destructive adjustments if you’re a Pro or Ultimate user). In the Exposure/Lighting section, open the Tone Curves tool.

open_curves

Inside the tool, notice the bars on either side of the x and y axis of the graph.

input

The dark area of the bar represents the shadows in your image. The middle represents the midtones, and the white area is the lightest parts of your image. You’re ultimately trying to improve the contrast of the image by changing which pixels map to the brighter area of the graph and which map to the darker area.

s_curve

Let’s take a closer look. The following photo is nothing special, but it is helpful for demonstrating the concept behind the graph. The input, represented on the x axis, shows you what tonal range the pixels in your image fall into. The Output, or the y axis, shows you where any of the given tones are mapped to. Look at any point on your x axis, find where it hits on the curve (the line through the graph), and then find where that hits the y axis: this is where the tone is being mapped to. As you can see in the histogram of this image, most of the pixels are concentrated in the area closest to where the axes converge — the shadows. And, as we haven’t made any changes yet, their output is also mapped to the shadows.

dark_tone_example

Now, for the sake of understanding, check out what happens when I move the curve down.

Curve_down

Even the pixels at the lightest point on the x axis are mapped low into the shadowy area on the y axis, hence the image is almost entirely black. Conversely, on this image below, I have moved the curve up, so even the darkest pixels on the x axis are mapped high into the light area of the y axis, and therefore, the image is significantly lightened.

curve_up

Generally, you want to achieve heightened contrast in your image. And this is done by what we call an “S curve”. It’s when you make an S with the curve, (you don’t say!), dragging the shadow section down, darkening the darkest pixels, and dragging the lights up into the highlight section, lightening the whitest pixels in the image. However, it’s important to note that you can’t add contrast to one tonal region without decreasing it in another region. The steeper you make the curve in the shadow region, the more detail you will get.

This image starts out kind of flat.

flat

But then—Tone Curves tool! Through an S curve, I made the dark darker and the light lighter, achieving greater overall contrast.

after_s_curve

But this is what happens if you get out of hand….Ok, it’s kind of fun.

crazy

Adjusting the Tone Curves tool is a useful time to take advantage of the Exposure Warning. Exposure Warning (blue)1 In the upper left corner of the tool, enable the button in order to display clipped shadows and highlights. Click the icon or press E on the keyboard, to highlight over- and under-exposed areas of the image.

You can also adjust the tonal range on a color by color basis. From the Channel drop-down menu, choose a color channel.

select_channel

Play with the curve to get the effect you want. Less is more if you are seeking a natural look.

red_colour_channel

From this point, you can really take it wherever you want, be that adjusting it in other tools, or being satisfied and sharing it in a variety of ways. That’s basically it. Hopefully this has shed some light on how to use the Tone Curves tool. I know at first I found the look of this graph as daunting as my first hill start in a standard. (A graph?? I don’t do math!) But once you understand how it works, it’s easy to get your lighting, color, and contrast show on the road. ;D

 

Comments
  1. Heiner says:

    where can i find such Tutorials in GERMAN? Also i miss a handbook like it is available for ADOBE LIGHTROOM.

  2. KOSTAX says:

    E para quando uma versão em Português???

    Português é a 5ª língua mais falada e escrita no mundo inteiro, e não tem direito a uma versão nem a tutoriais ???

  3. Hello,
    I would class myself as a medium level user of ACDSee, and am enjoying these tutorials immensely. The one tutorial I’d like to see is one that takes ‘botched’ pictures, or pictures with, say sun flare on them, and shows you, perhaps by referring to other tutorials or YouTube clips, how to at least try to salvage them. I have a Canon EOS 1000D, and I almost never use any of the auto setting. This means that sometimes I have the camera set on one thing (dimmed room, bright sunlight, fluoro tubes) but am taking a picture in a totally different situation and I forget to change the settings. It would help to know what to do to fix them without having to try all of the ACDSee features.

    • Hi,
      Thanks for the feedback! I would like to give it a shot. My biggest issue will be coming up with a botched photo that answers the questions you have. Are you talking generally about photos with lighting issues, or..? If you’re able to point me in the direction of an example, that would be most helpful. Thanks!

  4. anna says:

    Very basic. Real situations are much more difficult to solve than creating “S’ curve or moving to the right or left and there is no word about it.

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