Adobe Photoshop - Curves

This guide will show you how to read a histogram and add more dynamic range to your images.

The Curves adjustment layer is one of the best ways to improve the quality of your images, especially for images that are washed out or don’t have much of a difference between the darkest and lightest tones.

Using the Curves Adjustment Layer

The Curves adjustment allows you to manipulate the tones in the image and allows for precise control of the midtones of an image. With curves you can adjust the over-all contrast or tonal range, adjust the local contrast or adjust the color of an image.

  1. Select the Curves Adjustment Layer from the adjustments panel.
    • If the Adjustments panel isn't showing, go under the Window menu and then choose Adjustments.

The Histogram

The curves panel shows a histogram of the image being working with, with a diagonal line drawn through it. A histogram is a graphical representation of the tonal values of an image. It shows the amount of tones of particular brightness found in your photograph ranging from black (0% brightness) to white (100% brightness) (Figure 3)

The shadows are the lower left and the highlights are in the upper right of the line going through the histogram.

  1. Point the cursor to the middle and click to create a new point.
    • That would be the equivalent to a midtone slider and level.
  2. Drag this point down or lift this point up and note what is happening you the image.
  3. The point can also be moved or repositioned on the curve.
    • When working with curves, it does not take much movement of the sliders to impact the image.

The S Curve

  1. Add a point by clicking in a new spot on the curve in the shadows area of the histogram and drag down slightly to darken them.
  2. Click a secondary point in the highlight area of the histogram and drag up to lighten them.(Figure 5)
    • This has created an S curve to the image and increased the contrast.

Dynamic Range

Most images can benefit from adjusting the dynamic range. Dynamic range is the range from the darkest to the lightest tones that maintain accurate detail.

  1. Click and drag the White Point on the curve to the left until the point reaches the end of white point of the histogram.
  2. Click and drag the Black Point on the on the curve to the right until the point reaches the end of black point of the histogram

Changes can also be made to set the dynamic range by sliding the bottom slider left or right.

Changes can be made to specific color ranges by clicking on the RGB drop down menu, then choosing the specific color tone you want to make changes to.

By using an adjustment layer to accomplish these changes you have access to things like opacity, blend mode and the mask that comes along with that adjustment layer while making no destructive edits.

