3.4. Alien Map 2

Overview

This filter is found in Image>Filters/Colors/Map/Alien Map 2

This filter renders very modified colors by applying trigonometric functions. It has more possibilities than Alien Map 1. You will not find Sine and Cosine radio buttons because manipulating phase reproduces them. Alien Map 2 can work on RGB and HSV.

Options

Preview

This preview displays results of filter application interactively.

Mode

Radio buttons RGB Color Channel and HSV Color Channel let you select the color space you want to use.

Check boxes Modify ... Channel let you select RVB/HSV Channel you want to work with.

Sliders

For each channel, you can set Frequency (0-5) and Phaseshift (0-360) of sine-cosine funtions, using either sliders or input boxes and their arrowheads.

Frequency around 0.3 to 0.7 provides a curve that is similar to the linear function (original image), only darker or with more contrast. As you raise the frequency level, you'll get an increasing variation in pixel transformation, meaning that the image will get more and more "alien" (The GUM).

Phase alters the value transformation. 0 and 360 degrees are the same as a sine function and 90 is the same as a cosine function. 180 inverts sine and 270 inverts cosine (The GUM).