Hue and Saturation

Hue (sometimes referred to as tint) and Saturation are the two properties Photoshop uses to describe – and thus edit – an image.

Hue

Hue is the core color of an object. For example, in a rainbow, many pure hues are visible.

Saturation

Saturation can best be explained by the intensity of a given color, similar to the volume of music.

Fixing Color Cast

One of the biggest (most often performed) tasks a digital photographer or any photoshop user is to correct undesirable color shifts in photographs. There are several reasons why color cast can occur – improperly photographed image, errors in film processing, a bad scan, or and aged print are a few.

Regardless of the cause, color cast is a big issue: it can immediately affect the message of an image and dictate whether we like or dislike the image, and how we interpret the mood or meaning.

There are several methods to address the job of fixing color cast.

Image→Adjustments→Variations

Image→Adjustments→Auto Color

Image→Adjustments→Hue/Saturation

Each of these tools can be ‘faded’ or compensated by then applying the fade feature, Edit→Fade…

Using Curves to Adjust Color Cast

Curves can do more than adjust overall brightness and contrast as seen in the previous lesson. By manipulating individual color channels, the curves tool can significantly alter the color cast and tone of an image.

Colorizing a Grayscale (Black & White) Image.

As always, there are many ways to add color to a gray scale image. The Hue/Saturation command can be used to add color to an image, with a monochrome effect when using the Colorize Check Box.

Another method to employ is the Gradient Map. With this method, you can change the luminosity values (shades of gray in this case) with a specified color, in effect, swapping out a color for every shade of gray in an image, allowing for more compelling results.

Image→Adjustments→Gradient Map

Adjusting Color with Camera Raw

If a camera has the capability to capture an image in RAW format, photoshop can provide many adjustments to the file before opening it.

The RAW image format is a powerful way to gain control over nearly every aspect of an image – color temperature, tone, exposure, tint, saturation, sharpness, and contrast are only a few.

RAW image files incorporate non-destructive editing. This means that your original RAW file made at the time the photo was taken cannot be saved over. Only copies can be saved from the original, much like making prints from an original film negative.