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Glossary
IMAQ Vision for Visual Basic User Manual G-10 ni.com
linear filter A special algorithm that calculates the value of a pixel based on its own
pixel value as well as the pixel values of its neighbors. The sum of this
calculation is divided by the sum of the elements in the matrix to obtain
a new pixel value.
logarithmic function Increases the brightness and contrast in dark regions of an image and
decreases the contrast in bright regions of the image.
logic operators The image operations AND, NAND, OR, XOR, NOR, XNOR, difference,
mask, mean, max, and min.
lossless compression Compression in which the decompressed image is identical to the original
image.
lossy compression Compression in which the decompressed image is visually similar but not
identical to the original image.
lowpass attenuation Applies a linear attenuation to the frequencies in an image, with no
attenuation at the lowest frequency and full attenuation at the highest
frequency.
lowpass FFT filter Removes or attenuates high frequencies present in the FFT domain of an
image.
lowpass filter Attenuates intensity variations in an image. You can use these filters to
smooth an image by eliminating fine details and blurring edges.
lowpass
frequency filter
Attenuates high frequencies present in the frequency domain of the image.
A lowpass frequency filter suppresses information related to fast variations
of light intensities in the spatial image.
lowpass truncation Removes all frequency information above a certain frequency.
L-skeleton function Uses an L-shaped structuring element in the skeleton function.
luma The brightness information in the video picture. The luma signal amplitude
varies in proportion to the brightness of the video signal and corresponds
exactly to the monochrome picture.
luminance See luma.
LUT Lookup table. A table containing values used to transform the gray-level
values of an image. For each gray-level value in the image, the
corresponding new value is obtained from the lookup table.