Photoshop Curves Tool: 6 Techniques Every Photographer Must Know

The Photoshop Curves tool is one of the most powerful commands you have in the digital darkroom. But it can be intimidating to some. Here are 6 Photoshop Curves techniques every photographer should incorporate into their workflow.
 
Photoshop Curves Tool: 6 techniques every photographer must know
The Photoshop Curves command is your most powerful tool for adjusting tones to brighten, darken, add contrast and shift colours, yet many users choose to avoid it.
 
The problem is, despite being the most effective, it’s also one of the most difficult commands to get to grips with. This may be why Adobe has never included it in the more beginner-friendly Photoshop Elements.
 
As Elements gets better and better with every new release, the lack of a full Curves command remains one of the few big reasons not to plump for the more wallet-friendly version of Photoshop.
 
Beginners need not fear. After you’ve spent a little time experimenting, Curves quickly becomes the go-to tool for many tonal tweaks. It’s often the first edit you make on an image.
 
And as well as being one of the most powerful tools Photoshop has on offer, it’s one of the most versatile.
 
Whether you want to lighten a dark scene, boost contrast and colour, check for clipped pixels or make a variety of colour shifts, Curves is the tool for the job.
 
So, read on for six top tips to help you master the best tonal tool Photoshop has to offer.
 

Essential Photoshop Curves Techniques: 01 Curves Adjustment Layer

Essential Photoshop Curves Techniques: 01 Curves Adjustment Layer
Curves is best applied as an Adjustment Layer. Go to the Layers Panel, click the Create Adjustment Layer icon at the bottom and choose Curves.
 
Now your original image remains untouched.
 
Whatever settings you apply are editable by double-clicking the layer thumbnail, and you can take advantage of all the options working with layers allows, such as Masks, Blend Modes and Opacity.
 

Essential Photoshop Curves Techniques: 02 The Curve line

Essential Photoshop Curves Techniques: 02 The Curve line
You can drag anchor points up or down on the Curve line to lighten or darken tones.
 
Think of the X-axis as a scale from dark tones on the left to light tones on the right.
 
It’s important where you place a point, as this determines which part of the tonal range you wish to alter.
 
Points towards the left will target shadow tones, and towards the right will adjust highlight tones.
 

Essential Photoshop Curves Techniques: 03 Set white and black points

Essential Photoshop Curves Techniques: 03 Set white and black points
Hold Alt and drag inwards on the white and back point sliders (at the bottom right and left of the graph) for a greyscale view that shows any clipped pixels in your shot.
 
This is of great help when setting pure black and pure white tones.
 
Most images will benefit from containing a full range of tones, so drag the white and black points inwards while holding Alt until the point where pixels begin to appear.
 

Essential Photoshop Curves Techniques: 04 The amazing S-curve

Essential Photoshop Curves Techniques: 04 The amazing S-curve
Made by dragging one point upwards in the highlights and a second down in the shadows (and sometimes with a third to anchor the midtones) the S-shaped curve is a classic tonal tweak for boosting contrast and colour saturation.
 
The more pronounced the S-shape, the more the image will pop.
 
If you want to leave colour saturation unchanged, change the Blend Mode of the Curves Adjustment layer to Luminosity.
 

Essential Photoshop Curves Techniques: 05 Making selective adjustments

Essential Photoshop Curves Techniques: 05 Making selective adjustments
Make selective tonal changes to different areas of your image by painting Layer Masks to hide or reveal the Curves effect.
 
For example, portraits often benefit from a boost in the irises.
 
To achieve this, add a Curves Adjustment Layer and plot an S-shaped curve, then hit Cmd/Ctrl+I to invert the Curves layer’s mask to black.
 
Then grab the Brush tool, set colour to white, and paint over the iris to reveal the adjustment.
 

Essential Photoshop Curves Techniques: 06 Tweaking colour channels

Essential Photoshop Curves Techniques: 06 Tweaking colour channels
You can tweak different colour channels via the dropdown menu at the top of the Curves box.
By plotting different points along the colour line you can shift colours – for example, reducing reds as we’ve done in the hair here.
 
An upwards drag on the red line adds red and down adds cyan; up on the blue channel adds blue and down adds yellow; up on the green line adds green and down adds magenta.
 

In Depth – Inside the Photoshop Curves box

In Depth - Inside the Photoshop Curves box
1 Anchor Points
Plot these along the Curves line, then drag them up to lighten and down to darken.
 
2 White and Black Points
Drag these inwards to set new white and black points. Hold Alt while dragging for a view of any clipped pixels.
 
3 RGB Dropdown
Select different colour channels here access the red, green or blue Curves lines.
 
4 Preset
Choose from a list of handy presets, or use them as a starting point for further tweaks.
 
5 Pencil and Smooth
Toggle the Pencil tool on to draw a freehand Curve. Use the ‘Smooth Curves values’ option to smooth the line.
 
6 Adjust Brightness
Toggle the Hand icon on, then drag up or down over tones in the image to control brightness.
 
7 Histogram
A graphical representation of all the tones laid out in a ‘tonal range’, with shadows on the left and highlights on the right.
 
8 Eyedroppers
Toggle the eyedroppers on, then click over a tone in the image to set it as white, black or midtone grey.
 
9 Input and Output
Input represents the original tones in the image (the X-axis), while Output represents the new brightness value on a scale of 0-255 (the Y-axis).