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PIPS II Owners Manual and Users Guide
DigitalMicrograph maps an image's original data values to a color or gray-
scale value through a sequence of steps.
1.
Determine the contrast limits of the image's data
DigitalMicrograph uses two parameters, the low- and high-contrast limits, to
map the image's original data into a range suitable for display of the image.
Pixels in the original image below the low-contrast limit are treated as if they
were at the low-contrast limit and those above the high-contrast limit are
treated as it they were at the high-contrast limit.
DigitalMicrograph can determine these contrast limits "automatically" by
surveying the image, or "manually" using values entered by the user.
2.
Transform each mapped data value into a color index.
The mapped image values are then transformed into a color index that
indicates which color in the color table to use for displaying a particular pixel.
The Contrast Transform lines in the Histogram depict how this transformation
is performed. DigitalMicrograph supplies a number of standard contrast
transform methods and allows you to build a custom one if you desire.
3.
Display the pixel using the color table of the image.
DigitalMicrograph uses the color index to correlate each color in the color
table with pixels with specific intensities in the image. DigitalMicrograph
supplies a number of standard color tables, such as the gray-scale table, for
use in images and allows you to build a custom one if you desire.
Histograms
DigitalMicrograph will automatically calculate the histogram of an image
displayed using Raster or Surface Plot display types, and display it in the
Histogram palette. The Histogram palette also displays the Contrast
Transform lines and the color table in the Color Bar on the left of the palette.
The horizontal axis of the histogram represents data values with the left-most
side corresponding to the low contrast limit and the right-most side
corresponding to the high contrast limit. The vertical axis of the histogram
represents the number of pixels with a particular data value.
