Luminance – Hue and Saturation’s Step Brother

Thu, Jan 29, 2009

Lightroom, Workflow

luminance_insert1

There has been a lot of talk about the Hue, Saturation, and Luminance (HSL for your cool types) panel lately, so I though I would take you through an example of how I use the lesser known Luminance (L) control to solve issues that oftentimes I see folks attack with the Hue, Saturation, Exposure, or Tone Curve exclusively.

The Luminance control really is the red-headed step-child of the Hue and Saturation family. I find people rarely use it, and oftentimes if they do use the HSL panel it’s to target Hue and Saturation only.

I’ll admit my tendency to do the same.

For instance, if I see certain primary or secondary colors that need adjusting, it’s usually because they are over-saturated or a flattened hue (like skin) that I want to bring back to life. There are a few ways to work the Hue and Saturation to resolve issues – Targeted Adjustment Tools and the like – some of which which I have documented here.

But lately, I am finding that adjustments to the Luminance of an image are leading me to some very nice results that are far more targeted than previous approaches – and with less work.

Let’ s back up and define just what Luminance is … and I’ll make it simple:

Luminance controls the lightness or darkness for specific color ranges in your image

Ok easy enough right? I thought so too.

Let’s dig into an example project to see just what Luminance can do for us while working on an image that generally is OK, but could use some improvement – all achieved with Luminance adjustments.

{note: all tool, panel and module references are always in BOLD for easy reference as you map our workflow to Lightroom}

Here’s a quick before (bottom) and after (top) to help set the stage:

luminance1

My main issues with the image:

  • a bit too low in the exposure
  • flat skin tone
  • a tad too dark in the hair details
  • the red sweater (especially the forearm) is over-saturated in the red – and missing some highlight details as a result

In the past, I would have attacked these issues with a mix of the standard Lightroom tools (including but not limited to):

  • Exposure
  • Contrast
  • Fill Light
  • Hue and/or Saturation Adjustments

What’s missing? … you guessed it: Luminance

We can achieve all of these ‘fixes’ with simple adjustments to the Luminance slider.

We’ll begin by heading over to the Develop module (use keyboard shortcut D if you’re lazy like me), and selecting Luminance from the HSL panel:

luminance21

Now this is where things get interesting.

Keeping in mind that luminance is defined as the the lightness or darkness for specific color ranges in your image, let’s re-examine our original images issues, and how we might attack:

  • a bit too low in the exposure

but there IS an overall warm tone which we could adjust with the Orange slider

  • flat skin tone

overall brightness and depth could be adjusted for the skin tones using a mix of Orange and/or Yellow adjustments

  • a tad too dark in the hair details

similar adjustments for the skin could benefit the hair as well

  • the red sweater (especially the forearm) is over-saturated in the red – and missing some highlight details as a result

the details ARE there, but they are too dark in the Reds to come through

So now I have my plan of attack – let’s look at the Luminance settings after my adjustments:

luminance31

And again our resulting image before (bottom) and after (top):

luminance11

Not all the adjustments are as readily aparent in this image, so let’s step through each adjustment and its effect along the way:

Red +35

before (left) and after (right)

luminance4

Orange +20, Yellow +75

before (left) and after (right)

luminance5

Orange +20, Yellow +75

before (left) and after (right)

luminance6

Things to keep in mind

  • I am lucky to get 1/3 or possibly a bit more of pseudo-exposure correction with these controls – for images that need more exposure compensation you’ll still need to hit up the Exposure slider
  • If you attempt to target specific colors that already have a fairly high or low luminance value to begin with, you risk clipping those colors with results that can look noisy
  • EXPERIMENT – this control is quite possibly one of my favorites – it offers a very targeted level of control over your image
  • My one wish – a Luminance adjustment brush!
  • Share your experiences in the comments below

|Brandon Oelling
x=photography+consulting – image+workflow+technology+business

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10 Comments For This Post

  1. Michael W. Gray Says:

    I will attest to the importance and versatility of utilizing the luminance slider. In my film presets, especially slide films and cross processed emulations, luminance is the only tool that allows me to aquire the correct color tone to match the original film. On some, as mentioned in the article, it actually improves the overall exposure whilst not inducing noise enhancement.

    Great article, it is the first I have read on luminance anywhere and I am glad someone finally brought it to the spotlight. Great work as always.

    Michael W. Gray

  2. Vincent Says:

    Hi,

    you’re perfectly right, great demonstration !

    When I was still using Photoshop, I never touched the Luminance control you could find in the Hue Saturation command, because it had an overall action on all tones. But as you explain it, Lightroom enables to ajust luminance tone by tone, and it makes a big difference.

    I specifically use this tool on skin : I usually reduce the orange luminance (or yellow, depending on the picture) to give more texture to the skin (ok, sometimes you just want a soft and smooth skin, but sometimes you don’t). It also makes freckles more visible. But just like you say, this tool has to be used carefully, noise can quickly appear…

  3. Brandon Oelling Says:

    Thanks for the GREAT comments … I think I hit a good nerve on this one … Luminance does indeed ROCK!

  4. Julie McLeod Says:

    Thanks for that explanation of the effect of the luminance sliders. I’d played around with them before without really understanding their usefulness. Very helpful…

  5. Jayce Says:

    Thank you for this very lucid explanation of the Luminance part of HSL, and for verifying my need to keep testing any changes at full magnification (noise checking). I think this control has improved a lot since LR1 (or I am gradually learning more about what I am trying to do) but nobody has written much about it.

  6. Brandon Oelling Says:

    Jayce,

    I will agree the Luminance control is a finesse play … but one worth taming!

  7. Harry Says:

    Hi Brandon
    A great tip, and one which I will surely try,
    but!! I can’t help feeling that in your example, in the pictures of the little girls red sleeve, you have lost some definition/detail in the after version!

  8. Brandon Oelling Says:

    Keep in mind that just like any other image – detail/definition improvement is not a all inclusive adjustment – oftentimes you trade off detail in some areas for improvement in others – as is the case with my sample … the detail improvements are where they matter most – and this is always a subjective endeavor.

    Thanks for your comments Harry!

  9. Wouter Brandsma Says:

    This is very interesting stuff and a very different way to edit color photographs. But Luminance can be your best friend too for B&W photography. Make sure to bring all the sliders for saturation to -100 and than alter the luminance with the target adjustment tool. A great way to darken blue skies and lighten up skintones or greens. Without tone curves you can bring contrast to B&W photographs with the Luminance sliders.

  10. Brandon Oelling Says:

    Wouter,

    You are absolutely right!

    I think an supplement to this post with black and white examples is in order!

    Thanks for the tip … !

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