This filter creates outlines of shapes where there is a good contrast between the shape and the background. The result is a one pixel outline which can be expanded to give a key line. You can enhance the original contrast using gamma curves before running the filter.
Instructions
- Open the Filter Browser, and add a new filter set using the small + icon located in the middle of the browser. This will create a new ‘untitled’ filter set for you. This will appear in the top section of the Filter Browser. If you already have filter sets created, clicking the + button will duplicate the selected filter set.
- Select Line Work - Range from the list of available filters in the lower section of the Filter Browser.
- Double click on the name of the new filter set in the top section of the browser, and name it appropriately.
Range Mode
- Adjust the RGB minimum and maximum levels until you achieve the desired separation results.
- Tonal - will produce a tonal separation. Leaving this untucked will create a flat separation, commonly referred to as a mask.
- Over Image - will preview the separation over the original image.
In the snapshot below, the original data is on the left, and the filtered data is on the right.
Spot Mode
Follow the steps above.
- Using the Pipette Tool, click on the colour you want to separate. This will appear in the Tools Palette.
- Click the Set Colour button underneath the gamma pane
- Adjust the gamma curve until you achieve the desired separation results
In the snapshot below, the original data is on the left, and the filtered data is on the right.
Applying the filter
There are several ways to apply a filter:
- Click Apply - this will apply the filter to the active layer(s), and within a selection if there is one present in your file
- Click Make Layer - this will make a new layer in your file containing the filtered effect, leaving the original layer untouched
- Apply the filter using the Brush Tool - when you have finished building your filter set, simply close the Filter Browser. Then, open the Brushes Library, and select the filter you have just made from the drop down menu shown in the snapshot below. You can now paint with your filter.
Note: The default setting for the Brush Tool is ‘Brush”, located at the top of this drop down menu. To prevent you from becoming confused between the default setting and a filter setting, do not name any filters ‘Brush’. When you have finished painting with your filter, set the drop down menu back to the Brush setting, otherwise the Brush Tool may not behave as you would expect later on.