Adobe Photoshop CS5 for Photographers - Martin Evening [230]
RGB only filters
You will notice that most of the effects filters work in RGB mode only. This is because they can have such a dramatic effect on the pixel values and would easily send colors way out of the CMYK gamut if they were made available while working in CMYK. To unleash the full creative power of Photoshop plug-ins, you really do need to edit in RGB mode.
Filter essentials
Most Photoshop filters provide a preview dialog with slider settings that you can adjust, while some of the more sophisticated plug-ins (such as the Lens Correction filter) are like mini applications operating within Photoshop. These have a modal dialog interface, which means that whenever the filter dialog is open, Photoshop is pushed into the background which can usefully free up already-assigned keyboard shortcuts. With so many effects filters to choose from in Photoshop, there are plenty enough to experiment with. The danger is that you can all too easily get lost endlessly searching through all the different filter settings. There is not enough room to describe every Photoshop filter here, but we shall look at a few of the ways filters can enhance an image, highlighting those that are most useful.
16-bit filters
Photoshop supports a limited number of filters in 16-bit. However, most of the essential filters, such as those used to carry out standard production image processing routines, are all able to run in 16-bit mode.
Blur filters
There are 11 different blur filters in the Filter Blur submenu and each allows you to blur an image differently. You don't really need to bother with the basic Blur and Blur More filters, but what follows are some brief descriptions of the blur filters I do think you will find useful.
Adding a Radial Blur or Spin Blur to a photo
The Radial Blur can do a good job of creating blurred zoom and spin motion effects. For example, the Zoom blur mode, shown in Figure 10.1, can do a neat simulation of a zooming camera lens, while the Spin blur mode, shown in Figure 10.2, can be used to apply a circular spin effect (I also used a Spin Radial blur to add movement to the car wheels in Step 3 on page 543). The Radial Blur filter may sometimes appear to be sluggish, but it is after all carrying out major distortions of the image. For this reason you are offered a choice of render settings. For top quality results, select the Best mode, but if you just want to see a quick preview of the whole image area, I suggest you select the Draft mode option.
Figure 10.1 When using the Radial Blur filter in Zoom mode, you can create fast zoom lens effects such as in the example shown here on the right. You can also drag the center point in the filter preview dialog to approximately match the center of interest in the image you are about to filter.
Figure 10.2 When you use the Radial Blur filter in Spin mode, you can apply a circular spin blur effect such as the example shown on the right. Again, you can drag the center point in the filter dialog to match the center of interest of the image you are about to filter.
Average Blur
The Average Blur simply averages the colors in an image or a selection. At first glance it doesn't do a lot, but it is still a useful filter to have at your disposal. Let's say you want to analyze the color of some fabric to create a color swatch for a catalog. The Average filter merges all the pixels in a selection to create a solid color and you can then use this to sample with the eyedropper tool to create a new Swatch sample color (see Figure 10.3).
Figure 10.3 The Average Blur can be used to merge the