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.
 |
...GIF (3,024 bytes) |
 |
...JPEG Maximum (1,254 bytes) |
 |
...JPEG High (1,065 bytes) |
 |
...JPEG Medium (950 bytes) |
 |
...JPEG Low (873 bytes) |
|
|
|
|
|
|
|
|
|
|
|
|
 |
 |
 |
 |
 |