Adjustments with Curves

Important Adjustment Layer Step for each color adjustment:

• Create a new adjustment layer by clicking Layer>New Adjustment Layer
• Select Curves on the popup menu.

Adjusts the intensity values of pixels

Uses 0-255 scale while keeping up to 15 other values constant

• Lets you adjust the entire tonal range of an image, but instead of making adjustments using only three variables (highlights, shadows, midtones), Curves adjusts any point along a 0-255 scale while keeping up to 15 other values constant. You can also use Curves to make precise adjustments to individual color channels in an image.

Points along a curve:

A. Highlights

B. Midtones

C. Shadows

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The horizontal axis represents the current values of the pixels in an image or selected part of an image (input levels)

The vertical axis represents the tonal values after the curve is applied (output levels)

The default curve is a 45° straight line, in which Input and Output values are equal

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How to adjust color balance

To adjust tonal range and color balance using Curves for combined RGB, and the Red, Green, and Blue Channels separately, click Image>Adjustments>Curves to open the Curves dialog box, which looks like the above image.

To adjust the color balance of the image, choose the channel (or channels) you want to adjust from the Channel menu.

Click any points on the curve that you want to remain fixed. For example, if you want to adjust the midtones while minimizing the effect on the highlights and shadows, click the quarter and three-quarter points on the curve.

Do any of the following to adjust the curve:

• Drag the curve until the image looks the way you want it. Dragging the curve up lightens the image and makes it brighter
• Click a point on the curve, and enter Input and Output values for the point.
• Select the pencil at the bottom of the dialog box, and drag to draw a new curve. Hold down Shift to constrain the curve to a straight line, and click to define endpoints. When you're finished, click Smooth if you want to smooth the curve.

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Example: curves adjustment below

• raised the curve of the Red highlight and lowered the curve of the shadow to increase the contrast in the red flowers
• raised the curve of the Green highlight to lighten the green
• lowered the curve of the Blue shadow to increase the greenness of the leaves

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