The Bi-Color Filters in Color Efex Pro 4 simulate traditional glass bi-color filters by blending two colors and then adding the result to the image. Having the added benefit of total control of all the parameters such as Opacity, Blend, Vertical Shift, and Rotation offers a lot more flexibility in the digital darkroom.

To begin, let’s take a look at the Color Set. This offers 5 different Color Sets, which include different color variations. For example, when selecting Cool/Warm, the saturation of colors vary depending on if you choose Color Set 1, 2, 3, or 4.

The Opacity slider allows you to increase or decrease the strength of the filter effect. By moving the slider to the right to 100%, you will see the full effect of the filter. The opposite will happen by moving the slider to the left. At 0%, the filter effect is globally removed from the image.

The Blend Slider will transition the top and the bottom color making this a very distinct transition at 0%, or a very soft, subtle looking transition at 100%.

The Vertical Shift slider will move the horizon either all the way to the bottom at 100%, or to the top at 0%. The default is set to 50%, which is in the middle.

You can change the angle of the rotation of the filter in the image by moving the slider at a 360 or 0 degree angle or any angle in between.

Tip: To create a more realistic effect, try moving the Vertical Shift slider so that it aligns properly with the horizon line in your image. You can remove the effect, for example, off of the wave by adding a minus Control Point. By changing the opacity slider on the Control Point, this can create a more natural effect.