Lightroom Classic’s Parametric Curve: what it does, why it’s different

Lightroom Classic‘s Tone Curve panel has two modes. There’s the regular Point Curve mode, where you click to add control points to the curve and then move them around to change the curve shape – experienced photo editors will know this tool inside out – but there’s also a Parametric Curve mode. Is this just for beginners, or is it a new and better way to make curves adjustments?

In the Tone Curve panel, you’ll see white, red, green and blue circular icons for accessing the regular RGB curve and those for the individual colour channels, but you’ll also see a wavy line icon – you select this for parametric curve adjustments.

With these, the tonal range is split into four regions: Highlights, Lights, Darks and Shadows, with sliders for each. (You also get Parametric Curves adjustments in Lightroom, but without sliders, only markers on the bottom axis to mark these regions and grey overlays to show which region you’ll be adjusting – I think the Lightroom Classic implementation is better.)

You might instantly assume this is just a simplified beginner-orientated version of regular curves adjustments. I’m not sure I would agree. I’ve been using regular point curve adjustments for years, and even with experience it’s easy to overcook an adjustment and accidentally cross your curves into all sorts of horrible shapes. I like these parametric curves because they play nicely. The descriptions make sense to photographers, and the adjustments blend nicely with neighboring tonal regions.

There’s one type of shot where I always apply curve adjustments – what I would call ‘detail’ or close-up shots which are all about colours, contrast and textures, and this is what curves adjustments are good at bringing out.

What I usually find with this kind of shot is that they need a lot more contrast and colour than the camera’s standard rendering will provide. With almost all of my shots of this sort I do three things in sequence:

1. Apply Lightroom’s Auto tonal adjustments. Yes, this adds a level of Vibrance and Saturation which are often way too much for regular images but here, for once, will actually improve the colours.
2. Switch to the Parametric Curve panel and drag down the Darks slider. This has the effect of reducing the brightness while increasing contrast – exactly what you need for many ‘detail’ shots, where the camera’s default rendering is often just flat and bland.
3. Push up the Lights slider for a bit more contrast and ‘sparkle’, but not so far that the highlights start to visibly clip. And that really is just about all you need for this kind of image.

With detail shots, you don’t generally have high brightness ranges that clip easily. Quite the reverse – you often have a somewhat flat tonal range that needs a bit of a boost. You also don’t have to worry about realistic colours and saturation because the impact will often come from the intensity of the colour – and Lightroom’s Auto adjustments and curve adjustments will both boost colours very effectively.

So do try out Lightroom’s Parametric Curve adjustments, and don’t be afraid to push them as hard to get the effect you need, especially on detail shots like these. Never worry about how the histogram looks – it’s how the image looks that matters.