Filter NodesThe Filter nodes modify imagery (as opposed to combining it with other imagery like the Composite nodes). They take two inputs, the primary input and an optional control image input, as explained below in "Using Control Images with Filter Nodes ."
The Filter nodes include color adjustment and area operation nodes; therefore they are discussed in two groups: Using Control Images with Filter NodesThe filter nodes accept an optional input image that is used to control which pixels of the primary input image will be processed in the filter operation. Two control image parameters in the node panel enable you to specify which channel of the control image to use and how to use the channel data: the Control Action menu and the Control Channel menu. Control Action MenuThe Control Action menu lets you specify how the information in the selected control channel will be used. The two methods are On/Off and Mix, and in both cases the value of each pixel in the control channel governs how the corresponding pixel in the primary input image will be used. (The "corresponding pixel" refers to the pixel with the same x,y image coordinates.) On / Off MethodThe On/Off method specifies whether a pixel will be operated on by the filter:
Mix MethodThe Mix method uses the value of each control channel pixel to determine whether the corresponding pixel in the primary input will be filtered, and the extent to which it will be affected by the node operation. As with the On/Off method, a control channel pixel with a value of 0 will turn off filtering, and a pixel with a value of 1 will turn filtering on. However, pixels with values in between 0 and 1 will be filtered, and the output will be a mixture of the filtered and unfiltered value of the primary input pixel, with the ratio being determined by the floating point value of the control channel pixel. For example, a control channel pixel with a float value of 0.32 will turn on the filter 32 percent, so that the corresponding output pixel will be a mixture of 0.32 of the filtered input pixel value and 0.68 of the original input pixel value. Control Channel MenuThis menu enables you to specify which channel in the control image will be used to govern the control action, when the control image has more than one channel. |