Camera RAW: The Easy To Use Parametric Curve

Both Camera RAW and Lightroom have lots of horsepower to optimize RAW files. Although different in looks on the outside, the engines that drive exposure, color, sharpening, noise reduction, and other enhancements are identical. Camera RAW is bundled with Photoshop. Lightroom is a stand alone program. In LR, the develop module has the same features found in Camera RAW. What is shown in this tutorial can be performed in Lightroom.

When the Camera RAW converter is opened, the Basic Tab appears by default. Many photographers go no farther as a lot can be done in the Basic tab to optimize an image. As a matter of fact, many experienced PS and LR users go no farther. But if you want the ability to fine tune exposure and really take charge of subtle nuances of highlight, mid tone, or shadow control, the Parametric Curve is the answer.

The Parametric Curve is housed in the Tone Curve dialog box whose icon is highlighted in red on the accompanying image. Once opened, the user has the option to choose between the Parametric or Point curve. If you’re just getting started with curves or simply want subtle and easy curve control, Parametric is the way to go. The Parametric curve simplifies what’s otherwise a complex task using points on a tone curve.

The beauty, versatility, and simplicity of the Parametric curve lies with two key features: a) separate sliders allow the adjustment of just Highlights, Lights, Darks, and/or Shadows - see yellow ovals. b) fine tuning can be applied to each of the four tonal regions using the split controls along the bottom of the graph - see red rectangle. Overall, the highlights impact the right 25% of the graph, shadows impact the left 25% and the lights and darks represent the middle 50%. The split controls along the bottom allow you to expand or contract those four tonal areas so very specific targeted regions can be addressed. For instance, move the right most split control to the right, and only the brightest highlights will be impacted when the highlights slider is moved!

To get started using the Parametric curve, first apply all your optimizations in the Basic tab. The Parametric curve allows further tweaking of specific exposure values. Experiment moving just the highlights slider to the right to lighten them or to the left to darken them. If the range of highlights is too expansive or not broad enough, use the Split Controls to modify the range. Move the right split control to the right so the highlights slider effects just the brightest parts of the image. Move the right split control to the left so the highlights slider expands the bright range in the image. Perform the same tweaks and adjustments using the Lights, Darks and Shadows sliders in tandem with the Split Controls along the bottom of the graph to provide a precise range of exposure tweaks. Experiment by moving the sliders and split controls and watch the effects on the image.

If you’re familiar with the TAT, or Targeted Adjustment Tool, use it directly on the image to target specific exposure values. The TAT is found in the tool bar in the top left of the Camera RAW workspace - see the red square on the accompanying image.

Place it on the exact value you want to impact. Click and slide the mouse to the right to brighten that value or to the left to darken it. To see the benefit of the Parametric curve in real time, Google “How to Use the Parametric Curve in Photoshop” to find a good video that shows the nuances and power it has. I don’t use it all the time, but for those images where I need to really zero in on specific tonal values, it’s my GO TO to optimize exposure to the max.