Most color editing is based around the RGB system, where the image is split into red, green and blue color channels. But most programs also offer HSL, or hue, saturation and lightness adjustments – and this is where it gets interesting.
Global HSL adjustments aren’t very useful. If you shift the global hue of an image it quickly looks wrong. The real strength of the HSL system is the way it lets you separate and edit individual colors.
These screenshots are from Capture One, but you can do the same things in other programs. The tools may look a little different, but the principles and the effect are the same.
The HSL model is a much more intuitive way to look at color. The Hue value defines the color itself, the Saturation value is its strength and the Lightness value is its brightness.
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What you can do in (most) software is edit the HSL values of individual colors within the image, either by selecting a broad color range with a button or by using an eyedropper or a targeted adjustment tool to select a color directly in the image.
So what kind of adjustments can you make? Here are a three examples.
1. Bluer skies
You can use a polariser to make blue skies richer, or you can do it in software. The problem with polarisers is that you have to own one, and to have it with you! The second is that with wide-angle lenses the polarising effect may affect a narrower angle than the lens itself and product an artificial looking transition.
With the digital method, you can choose exactly the tone and depth of blue you want and without affecting the rest of the colors. You can also fix any issues with the color rendition. For example, I find Capture One’s blue skies have a hint of cyan which I like to take out with a hue adjustment.
- Select the sky: I used the Capture One Color Editor in Advanced mode to select the sky. For each selective color adjustment you can adjust that color’s Hue, Saturation and Lightness.
- Reduce the lightness: This is the first step to making a blue sky more intense and not saturation, interestingly.
- Reduce the saturation: Reducing a color’s lightness also has the effect of intensifying it, so you should reduce the sky saturation to keep it looking natural.
I also like the faded ‘vintage’ blue effect you get in some Capture One Styles, which you can create with a hue shift in the other direction, with reduced saturation and reduced lightness.
2. Fresher foliage
Grass and leaves can often take on a rather faded, yellowish look that you don’t notice at the time but can look disappointing later on. You can fix this by selecting the yellow-green color (foliage is often very close to yellow) and then shifting the huge towards a cooler green. It can make a huge difference, really quickly, though it is easy to go a little too far.
- Select the grass: It’s the same process as before, using the eyedropper to click on a representative area of grass (other programs will offer their own color selection tools).
- Shift the hue: Moving the hue slider to the right makes the color cooler and, with vegetation, ‘fresher’.
- Boost the saturation: It doesn’t need much, but a small boost to the saturation value makes the grass greener.
- Reduce the lightness: A small reduction to the luminance makes the green of the grass just a little more intense.
3. Better color separation
Similar colors can run together more than you expect, so if you like photographing flowers or richly-colored fall foliage, it can be difficult to get enough contrast between the different shades for them to really stand out.
The way to tackle this is to select each of the similar colors and then separate them with hue, saturation and lightness adjustments that exaggerate the differences. This is easier if you have a targeted adjustment tool for selecting colors precisely.
- Select and adjust the first color: With this image I decided the first step was to make the yellow-brown colors in the background brighter.
- Select and adjust the second color: This time I selected the deep red of the leaves and increased the saturation and reduced the brightness to distinguish it more clearly from the background.