The Shadows And Highlights Screen - Microtek ScanMaker IIG User Manual

The Shadows and Highlights screen

1
2
1 The Histogram is a graphic representation of how all the pixels in an image are
distributed across brightness and darkness levels. The darkest pixels are at the left;
the lightest pixels are at the right.
• A histogram skewed heavily to the left indicates that the image has many more dark
pixels than light.
• Conversely, a histogram skewed heavily to the right will indicate a light image as it
has more light pixels than dark.
• The height of the histogram indicates the number of pixels at that point in the
histogram.
2 The Triangles (indicators) below the histogram adjust the Shadow, Midtone, and
Highlight settings.
• The black (left) triangle controls the shadows. Moving this triangle to the right will
emphasize shadows and create a darker image.
• The gray (middle) triangle controls the midtones and indicates how the brightness
and darkness pixels are divided. Moving it to a value less than 1.0 will have the
effect of darkening the image. Moving it to a value greater than 1.0 will have the
effect of lightening the image.
• The white (right) triangle controls the highlights. Moving this triangle to the left will
emphasize highlights and create a lighter image.
Note: The gray and white triangles will change in color if a color channel (not Master)
is selected in the Channel box.
3 The Histogram bar shows the distribution of shades from dark to light (left to
right). The distribution of shades changes as you move any of the triangles.
4 The Input edit boxes show how pixels are distributed over the 0-to-255 pixel scale.
The input values are related to the position of the indicators along the histogram. For
example, if you move the left triangle in from 0 to 30, the input range becomes 30 to
255, and pixels in the range of 0 to 30 are then set to 0. In a process called mapping,
the new range (30 to 255) is stretched back to become 0 to 255. The image then
becomes darker, since all pixels from 0 to 30 are now mapped to black (whereas 0 to
30 before had subtle gradations from black that lightened gradually).
The same principle applies when you move in the right triangle, and the highlights in
the image become more pronounced.
Moving in any of the triangles above the input boxes will change the values in the
boxes. You can observe how the values in the boxes are affected by moving the
triangles, or you can enter values into the boxes directly. In both cases, the histogram
will change accordingly.
4
3
Reference: The Settings Window 5-63