National Instruments IMAQTM - Manual (Page 103)

Glossary
IMAQ Vision for Visual Basic User Manual G-6 ni.com
gradient filter An edge detection algorithm that extracts the contours in gray-level values.
Gradient filters include the Prewitt and Sobel filters.
gray level The brightness of a pixel in an image.
gray-level dilation Increases the brightness of pixels in an image that are surrounded by other
pixels with a higher intensity.
gray-level erosion Reduces the brightness of pixels in an image that are surrounded by other
pixels with a lower intensity.
grayscale image An image with monochrome information.
grayscale morphology Functions that perform morphological operations on a gray-level image.
H
h Hour.
highpass attenuation The inverse of lowpass attenuation.
highpass filter Emphasizes the intensity variations in an image, detects edges or object
boundaries, and enhances fine details in an image.
highpass frequency
filter Removes or attenuates low frequencies present in the frequency domain of
the image. A highpass frequency filter suppresses information related to
slow variations of light intensities in the spatial image.
highpass truncation The inverse of lowpass truncation.
histogram Indicates the quantitative distribution of the pixels of an image per
gray-level value.
histogram equalization Transforms the gray-level values of the pixels of an image to occupy the
entire range of the histogram, thus increasing the contrast of the image.
The histogram range in an 8-bit image is 0 to 255.
histogram inversion Finds the photometric negative of an image. The histogram of a reversed
image is equal to the original histogram flipped horizontally around the
center of the histogram.
histograph Histogram that can be wired directly into a graph.