Mosaics


One significant milestone in the history of visual art was the ability to portray tonality . Tonality is the effect of changing light or color on an image. In the real world, we see a seamless continuum of blended color that defines our visual world in light and shadow, and produces a tangible , three-dimensional reality of color and form. Primitive artists made no attempt to express tonal differences, in part because the technology was unavailable to them.

If you think that tonal variations in digital images is a new phenomenon , however, think again. One of the first methods of simulating the effect of tonal variation was to place tiny individual units of slightly varied color next to each other. We see this technique commonly employed in mosaics from imperial Rome, such as the one in Figure 1.1. Each element of color is a separate glass or ceramic tile. The tiles, placed next to each other in a graduated sequence, produce the effect of varied tonality.

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Figure 1.1: A mosaic from first-century B.C.E. Pompeii, The Defeated Persians under Darius (detail)

The mosaics of two thousand years ago are the predecessors of today s Photoshop images. Instead of tiles of glass, the digital artist uses squares of colored light called pixels (see Figure 1.2). Today s scanners can see and interpret color information from a continuous-tone image into these tiny units. When the image has been captured, we can, in Adobe Photoshop, select and change the color of pixels individually or in groups.

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Figure 1.2: A close-up of a digital image displaying its pixels



Photoshop CS Savvy
Photoshop CS Savvy
ISBN: 078214280X
EAN: 2147483647
Year: 2004
Pages: 355

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