White balance controls in Camera Raw

White balance controls in Camera Raw 

In very simple terms, adjusting the white balance is a matter of identifying what objects in the image should be neutral-colored (white or gray) and then adjusting the colors in the image to make those objects neutral-colored. A white or gray object in a scene takes on the color cast by the ambient light or flash used to shoot the picture. When you use the White Balance tool to specify an object that should be white or gray, Camera Raw can determine the color of the light in which the scene was shot and then adjust for scene lighting automatically. 

 

A. Moving the Temperature slider to the right corrects a photo taken with a higher color temperature of light B. Moving the Temperature slider to the left corrects a photo taken with a lower color temperature of light C. Photo after color temperature adjustment

Color temperature (in Kelvins) is used as a measure of scene lighting because natural and incandescent light sources give off light in a predictable distribution according to their temperature. A digital camera records the white balance at the time of exposure as a metadata entry. The Camera Raw plug‑in reads this value and makes it the initial setting when you open the file in the Camera Raw dialog box. This setting usually yields the correct color temperature, or nearly so. You can adjust the white balance if it is not quite right. The Basic tab in the Camera Raw dialog box has three controls for correcting a color cast in an image:

White Balance

Camera Raw applies the white balance setting and changes the Temperature and Tint properties in the Basic tab accordingly. Use these controls to fine-tune the color balance.

As Shot

Uses the camera’s white balance settings, if they are available.

Auto

Calculates the white balance based on the image data.

Note: If Camera Raw doesn’t recognize the white balance setting of a camera, choosing As Shot is the same as choosing Auto.

Temperature

Sets the white balance to a custom color temperature. Decrease Temperature to correct a photo taken with a lower color temperature of light; the Camera Raw plug‑in makes the image colors bluer to compensate for the lower color temperature (yellowish) of the ambient light. Conversely, increase Temperature to correct a photo taken with a higher color temperature of light; the image colors become warmer (yellowish) to compensate for the higher color temperature (bluish) of the ambient light.

Note: The range and units for the Temperature and Tint controls are different when you are adjusting a non-camera raw image, such as a TIFF or JPEG image. For instance, Camera Raw provides a true-temperature adjustment slider for raw files from 2,000 Kelvin to 50,000 Kelvin. For JPEG or TIFF files, Camera Raw attempts to approximate a different color temperature or white balance, but because the original value was already used to alter the pixel data in the file, Camera Raw does not provide the true Kelvin temperature scale. In these instances an approximate scale of -100 to 100 is used in place of the temperature scale.

Tint :  Sets the white balance to compensate for a green or magenta tint. Decrease Tint to add green to the image; increase Tint to add magenta.