Correct vs. Apply Color. What is the difference?

By: Kevin K. Gordon, CTO SCGI

The two Asiva® Operations Correct Color and Apply Color may sound similar but are very different in how they work and how they should be used. These two Operations are found in Asiva Photo and in the Correct+Apply Color plug-in for Photoshop®. In the most general sense, Correct Color changes one or more colors to a color, and Apply Color paints a color on top of one or more colors. In other words, Correct Color 'replaces' the original color pixels with another color, and Apply Color simply applies a color on top or the original using a blend amount to create a new color. Both of these Operations use Asiva's three Maps (Hue, Asiva Saturation and Luminance) to specify the source colors to be affected and how much to affect them. They both have a Target Color you can choose and modify at any time. This makes it easy to create variations once you have the curves in your Maps set properly. However, the Apply Color Operation has a Blend Amount Slider not found in Correct Color.

The Correct Color Operation changes one or more colors in the source image to a user-specified Target Color, while trying to maintain the pre-existing range of shadows, mid-tones, and highlights that existed in the source color(s). Correct Color will create variations of saturation and luminance of the Target Color that best fit into what has been selected by the three Maps.

The appropriate use of Correct Color would be when you want to change some particular color or colors to a single other color, while maintaining the integrity of the existing shadows, mid-tones, and highlights. For example, Correct Color could be used to remove color-casts from drum-scanned images. It could also be used to change a range of tones existing in a face, say from magenta to reddish-brown, to a single consistent hue. A great use for this Operation is to create color-matched catalog items of different colors, from automobiles to apparel, where only one picture was taken.

The Apply Color Operation is the closest to the “Paint Bucket Tool”, or fill with color, in Photoshop® when used in conjunction with the “Color Range” selection capability and an opacity level. The Apply Color Operation puts the user-defined Target Color on top of the source color(s), which are specified by the curves in the three Maps. The Target Color is blended with the selected source color(s) as specified by the Blend Amount Slider.

The appropriate use of Apply Color would be when you want to slightly modify some existing color, and you want to cover-up some imperfections at the same time. You may also want to fill-in some gradated color into shadows or highlights. So Apply Color could be thought of as digital color makeup. For example, you could use Apply Color to apply a reddish-brown color to flesh-tones, particularity the shadows. Used in conjunction with the Blend Amount Slider and Maps, you could change the color-cast of a person’s skin while covering-up slight blemishes and imperfections, and even reducing the harshness of a portrait. Another example might be cleaning up a noisy sky, making the blue purer at the same time. Applying a pure blue with an appropriate blend amount would clean up the noise and make the sky look better too!