Support for multiple external images in Filter Forge is implemented by allowing you to load images into Color Controls and Grayscale Controls via the Settings tab in Filter Controls. The picture below shows the Color and Grayscale controls in the Filter Editor:
As the screenshot suggests, a filter can load as many external images as there are Color Controls. By default, the new control components don't accept images, but you can easily configure that in their properties:
It is important to understand that Filter Forge does not store or embed the external image in the filter itself – all it stores is a reference to the external image specified by its filename and path.
Also, filters containing references to external images cannot be submitted to the online filter library – they will be rejected by the Submit Wizard. To submit filters that use multiple images, you will have to replace all references to external images with references to Filter Forge's built-in preview images.
