Making images or parts of images lighter, or brighter, is a commonly needed adjustment. There are many ways to lighten an image in Photoshop. You can use a lightening process that lightens the light and/or dark qualities of an image (the luminosity or luminance) along with the colors in an image.

But let’s say you’ve got the color the way you want it — you just want to lighten part of the image and avoid risking a shift in the color while you’re at it. In that case, you can use a lightening technique that lightens only the luminosity and does not affect the colors. There are also lightening techniques that can better preserve contrast in an image, and others that may reduce contrast. You can use certain methods to make broad changes or you can use methods that allow you to target specific areas.

All of the following techniques require a Curves adjustment layer. To make a Curves adjustment layer, do the following:

• Activate the layer that you want to be just below the Curves adjustment layer you are about to make. (An adjustment layer can affect only the layers below it.) You can activate a layer by clicking once on it in the Layers palette — clicking next to the right side of the layer name is best.
• Do one of the following:
  • Click the Create a new fill or adjustment layer button (the half-black, half-white circle) at the bottom of the Layers palette and choose curves.
  • Click the curves button in the Adjustments palette.
• For some of the tasks described below, you need to activate the Curves adjustment layer and adjust it in the Adjustments palette. For other tasks, you need to activate the Curves adjustment layer and work with it in the Layers palette.

Note that the color mode of the image determines whether you need to move the curve up or down to lighten the image. Color mode can be changed in the Image > Mode menu. You can preserve more colors in an image by adjusting it in RGB or Lab color mode.

When you convert an image to CMYK color mode, which is eventually necessary for full-color images destined for print, you lose some of the colors. Sometimes the loss of colors is noticeable, and sometimes it’s not. So it’s best, although not absolutely necessary, to convert to CMYK only when you are nearly finished with the image.

Caution: When you are adjusting curves, be careful not to overdo it to the point that your image loses detail in areas that are important to you or that need to be preserved for reproduction on its destination device. For example, the lightest areas in images destined for print need to be a little darker than pure white and the darkest areas a little lighter than pure black to maintain print quality in a typical image.

You can lighten broad areas of an image by adjusting the curve in a Curves adjustment layer so that the majority of the curve is moved from its original straight, 45-degree-angle line in the direction of the light part of the dark-to-light bar that runs along the side of the curve.

If the resulting curve is made so that part or all of it is at a steeper angle than the original 45-degree-angle curve, the corresponding part of the image will have increased contrast. If the resulting curve is made so that part or all of it is at a less-steep angle than the original 45-degree angle of the curve, the corresponding parts of the image will have decreased contrast.

Note: When referring to the steepness of the curve line, the reference is to the steepness of the angle of the line, not necessarily whether the line is moved to a point that is higher than, or above, the original curve line.

The three illustrations below show before-and-after images in RGB, Lab, and CMYK color modes and the curves that lightened broad areas of the images while increasing the images’ contrast. When you are looking at the curves in the figures, notice the direction in which the curves are moved. Curves aren’t necessarily moved in the same direction to lighten or darken an image. It depends on the color mode of the image. Use the dark-to-light bar that runs along the side of the curve as a guide when you are deciding which way to move the curve. To lighten, move the curve toward the light part of the bar; to darken, move the curve toward the dark part of the bar.

An RGB mode image that uses a curve to lighten broad areas of the image while increasing the image’s contrast. Note that part of the curve angle is steeper than it was originally and the composite color RGB channel is active in the curves dialog box.

A Lab mode image that uses a curve to lighten broad areas of the image while increasing the image’s contrast. Note that part of the curve angle is steeper than it was originally and the Lightness channel is active in the curves dialog box rather than a color channel.

A CMYK mode image that uses a curve to lighten broad areas of the image while keeping some of the image’s contrast. Note that part of the curve angle is steeper than it was originally and the composite color CMYK channel is active in the curves dialog box.

The next three illustrations show before-and-after images in RGB, Lab, and CMYK color modes and the curves that lightened broad areas of the images while reducing the images’ contrast.

An RGB mode image that uses a curve to lighten broad areas of the image while reducing the image’s overall contrast. Note that all of the curve angle is less steep than it was originally and the composite color RGB channel is active in the curves dialog box.

A Lab mode image that uses a curve to lighten broad areas of the image while reducing the image’s overall contrast. Note that all of the curve angle is less steep than it was originally and the Lightness channel is active in the curves dialog box rather than a color channel.

A CMYK mode image that uses a curve to lighten broad areas of the image while reducing the image’s overall contrast. Note that all of the curve angle is less steep than it was originally and the composite color CMYK channel is active in the curves dialog box.