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Use the gray scale above (divided into 5%
increments) to adjust your monitor brightness and
contrast. The black area should be maximum black,
and the white pure white. Each step should be
distinguished from its neighbors.
Images are typically displayed on computer screens
with 72 pixels per inch. Reducing a photographic
image from 600 ppi or 300 ppi to 72 ppi while
preserving viewability is a challenge. An 8 pixel
window may become 1 pixel wide, leaving a lot to
the imagination.
The appearance of the JPEG images is affected by
the alteration of values by the compression,
whereas GIF files are not compressed. I have stored
examples of GIF and the various JPEG settings. You
decide.
The grayscales below were saved from the same
Photoshop 3.0 format master file in which 256 one
pixel wide vertical bars were created with
Photoshop. The appearance of the JPEG images is
affected by (1) the alteration of values by the
JPEG compression and (2) the interpretation
of the data by the display hardware/software.
Although visual differences between the JPEGs are
discernible with increased magnification, they
appear remarkably similar on my monitor.
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...GIF (3,024 bytes)
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...JPEG Maximum (1,254 bytes)
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...JPEG High (1,065 bytes)
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...JPEG Medium (950 bytes)
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...JPEG Low (873 bytes)
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GIF
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JPEG Max
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JPEG High
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JPEG Medium
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JPEG Low
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12.4K
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7.7K
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5.9K
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4.8K
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3.9K
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