Page 113 - Enhancing CAD Drawings with Photoshop

4386.book Page 96 Monday, November 15, 2004 3:27 PM

96 CHAPTER 3 DIGITAL DARKROOM SKILLS

Simulating Camera Effects
The way photographs represent reality has become part of every person’s subconscious mind today.
Traditional film cameras have several shortcomings that we take so much for granted today that we
almost see evidence of these shortcomings as proof of the reality of an image.
Take film grain for example. The chemical development process exposes “grain” under certain light-
ing and aperture settings, in which the photosensitive emulsion forms a random organic pattern. In con-
trast, digital cameras and computer-generated imagery has no inherent grain. Consequently, digital
imagery often appears “computer generated” or somehow less than real to our subconscious minds.
Cameras are designed to let light pass through their glass lenses and either expose film or a
charge-coupled device (CCD) sensor, for example. Sometimes light rays reflect internally within
the optical system and produce lens flares, or chromatic aberrations. Lens flares are sometimes used
to make computer-generated imagery seem more realistic because it makes us subconsciously
believe the shot was taken with a real camera. Let’s take a look at how this works.
1. Open the file Building.psd from the CD. Figure 3.28 shows the original computer-generated
image.
2. Press Ctrl+J and rename the duplicate layer Lens Flare.

3. Choose Filter Render Lens Flare to open the Lens Flare dialog box, as shown in Figure 3.29.
4. Click a point high up on the glazing system (shown in Figure 3.29) to locate the flare center.
Drag the Brightness slider to 75%, and click the 105mm Prime lens radio button. Click OK. The
lens flare appears and looks like the reflection of the sun in the glass of the building and inter-
nally within the camera lens.

Figure 3.28
The original computer-
generated image