Lets you load a bitmap image and use each row of pixels of the bitmap as an animated gradient. When a bitmap is loaded into a gradient control, Lens Effects reads the first 100 pixels across the top row of the image (for the 100 divisions of its gradient controls) and makes them the gradient. With each successive frame, Lens Effects reads in the next row of pixels as the gradient. When you scrub the animation slider, you can see the gradient change over time.
The last five options on the shortcut menu are different types of compositing methods. When you work with Color and Transparency gradient controls in any of the Lens Effects filters, you must be aware of both the Radial and Circular gradients. Both Lens Effects color gradients and both Transparency gradients are "locked together" and will work together based on the compositing method you choose to create an effect.
Each compositing method works on a pixel-by-pixel basis on the positional value in both gradients. The compositing methods define how the colors and brightness values are combined to form a single color. When combining the colors, the algorithms evaluate each color channel of the color to find the end result. This lets you create five very different looking effects with the same two gradients.
When this option is selected, the higher color or brightness value between the two gradients is selected. For example, if you had a color with RGB values of 255,210,255 and another with 225,240,225, the resulting color would be 255,240,255. This option generally results in a slightly brighter lens flare than the default settings.
This is the most common way of using only one gradient. Set one gradient to the color or brightness you desire, then set the other gradient to pure black. This assures that all of the values you set in one gradient are used exclusively to achieve the effect.
Compositing methods are applied to every gradient. Some gradients are linked together, so if you assign a specific compositing method to one, the compositing method is automatically assigned to the other.