5 Turn on the Preview option to check the filter effect. When the settings are correct, click OK. To save a custom filter:  In the Custom dialog box, enter the fil- ter settings and click Save. Enter a name and location for the filter and click Save. To load a custom filter:  In the Custom dialog box, click Load. In the directory dialog box, select the filter file and click Open. Combining image channels The Calculate Image command lets you combine channels to create selection masks for effects like embossing text in an image. By add- ing, subtracting, and multiplying channels, you can also enhance shadows and highlights. The Calculate Image command combines corresponding pixels from two channels by the method you choose. You can place the result in a new or existing channel. To combine channels 1 With an image in edit mode, choose Image > Calculate. 2 Choose the first channel in the Source 1 menu. If you want to invert the channel, select Invert. For more information, see “Invert- ing colors in images” on page 34.687. 3 In the Source 2 menu, choose the channel you want to combine with the Source 1 channel. If you want to invert the channel, select Invert. 4 In the Blending area, choose an option in the Use menu. See “Descriptions of Calculate blending options,” page 35.725 5 Enter an opacity from 0 to 100 percent for Source 1. Other options are available for some Blending methods. 6 If you want to mask Source 1, select Mask in the Blending area and choose a channel in the menu. To invert the mask, select Invert in the Blending area. 7 Choose the name of a destination channel or choose New in the Result menu. If you select an existing channel, Canvas replaces the channel with the results of the Calculate Image operation. 8 Click OK to calculate the channel using the current settings.
Canvas 8 Help: Image filters and effects (18 of 20)                                                 Page #724