Absolute Beginner's Guide to Digital Photography

CHAPTER 2 ADVANTAGES AND DISADVANTAGES OF DIGITAL CAMERAS 21

FIGURE 2.5
Foveon’s
three-layer
technology.

Aliasing and Other Imager Problems

The following images demonstrate problems that occur with low-resolution sensors

and poor camera software. The images have been magnified so that you can see the

pixelation and artifacts.

The original image direct from the camera has red, green, and blue intensities (see

Figure 2.6) in ratios of 1:2:1, which gives it a distinct green cast. There is twice as

much green data. Each channel is adjusted in software to make it clearer.

After decreasing the green intensity by 50 percent (see Figure 2.7), the color balance

of the raw Bayer mask data is about right.

FIGURE 2.6
The CCD mask
creates a red,
green, and blue
image.

Red Pixels

RGB Image

Bayer RGB pattern Green Pixels

Blue Pixels

GRGRGRGR

GRGRGRGR

GRGRGRGR

GRGRGRGR

L GL GL GL G

L GL GL GL G

L GL GL GL G

L GL GL GL G

Demosaic

Demosaic

Demosaic