Area Operators

These are operators that operate on pixel windows. As each pixel in the image is visited, values of pixels in a window or neighborhood around the current pixel are used to process the current pixel.

Operator	Description
average	Each pixel value is assigned a value based on the average value of pixels in a window around it.
convolve	Convolve a kernel with the image. (sum of products)
correlate	Match a kernel to each pixel in the image. (sum of the difference of pixel intensities between kernel and image)
feature	Highlights bright/contrasting features in the image. (difference of eigenvalues)
max	Each pixel value is assigned the highest intensity value of the pixels in it's neighborhood.
min	Each pixel value is assigned the lowest intensity value of the pixels in it's neighborhood.

Arithmatic and Logical with Constants

Graphics operators don't necessarily perform interesting image understanding operations, but they do make interesting interactive pictures. Some operators just display information, others create effects based upon image content.

Operator	Description
+,caddd	Add a constant to the pixel values in an image.
-,csubtract	Subtract a constant to the pixel values in an image.
*,cmultiply	Multiply a constant to the pixel values in an image.
/,cdivide	Divide a constant to the pixel values in an image.
!,not	Inverts an image.
&,cand	And a constant to the pixel values in an image.
|,cor	Or a constant to the pixel values in an image.
=,set	Set the values in the image to the given constant.

Arithmatic and Logical Operators Between Images

Graphics operators don't necessarily perform interesting image understanding operations, but they do make interesting interactive pictures. Some operators just display information, others create effects based upon image content.

Operator	Description
add	Add two images.
subtract	Subtract two images.
and	And two images.
or	Or two images.

Basic Operators

These are operators that are grouped together because they were amoung the first created. They perform a wide variety of useful tasks and some are used quite frequently.

Operator	Description
background	Grabs the background at a specific point in time and subtracts this from the incomming image. Also has an adaptive mode.
cut	Cuts out a specific range of intensities. Good for filtering out unwanted noise.
difference	Subtracts the current frame from the last one. Detects the amount of motion.
level	Creates a binary image using the greator than or equal operator.
normalize	Normalizes the image to full spectrum.
locate	Calculates the size and location of all pixels with an intensity above a threshold.

Color Operators

Color operators work by manipulating color information toward a specific result. While most operators work on color images, color operators use the color information to get at color specific information.

Operator	Description
color	Cuts out all pixels that don't match a set of color values.
compact	Creates an image with a single plane of information from an image with multiple planes of information.
extract	Removes one plane of color from an image to make a new one plane image.
pack (not working)	Takes a set of images in each inlet and constructs a composite by coping each image to a different color plane of one image.
unpack	Separates out each color plane to an individual image. Outputs each image to a separate outlet.

Filter Operators

These are operators that filter pixels in the image.

Operator	Description
depix	Removes single pixel noise.

Information Operators

Operators that get specific bits of information from the image.

Operator	Description
getcount(Not Implemented)	Gets the overall count of the number of pixels within threshold in the image (Not implemented, see locate).
getintensity	Gets the overall intensity of the image.
getlocation (Not Implemented).	Gets the location of pixels within threshold in the image (Not implemented, see locate).
getrange	Gets the minimum and maximum intensity values in the image.

Histogram Operators

These are operators create or operate on histograms.

Operator	Description
histogram	Creates a histogram of the image. Outlets the histogram as a new data type out the third outlet.

Graphics Operators

Graphics operators don't necessarily perform interesting image understanding operations, but they do make interesting interactive pictures. Some operators just display information, others create effects based upon image content.

Operator	Description
boid	Flock of birds (lines) effect.
ascii	Converts the image to ascii representation.
display	Displays an image.
flow	Flows of lines effected by the image content.
hdisplay	Displays a histogram.
rdisplay	Displays a region list.
stillness	Averages images over time. Creates a picture of what is not moving in the image.
words	Creates an window of words from a region list.

Region Operators

Graphics operators don't necessarily perform interesting image understanding operations, but they do make interesting interactive pictures. Some operators just display information, others create effects based upon image content.

Operator	Description
blobs, regions	Converts an image to a list of regions. Tracks these regions over time. Calculates location, size velocity, extents, etc..
rparse	Parses the region list produced by blobs or regions and dumps various values (like location) for each region.
rsize	Parses the region list and dumps out the sizes of each tracked object.

Threshold Operators

Thresholds modify the image by dividing pixel intensities into two levels, creating what is called a "binary image". Each pixel in the image is compared to a value called a threhsold. If the pixel intesity is inside the range of the operator (for '>', inside is intensities that are greator than threshold) the pixel's value is set to one value (default is 255), and if the pixel's intensity is outside the range of the threshold, its value is set to another value (default is 0).

Operator	Description
threshold	Creates a binary image based on two threshold values and a specified operator.
>	Creates a binary image using the greator than operator.
<	Creates a binary image using the less than than operator.
>=	Creates a binary image using the greator than or equal operator.
<=	Creates a binary image using the less than or equal operator.
<>	Creates a binary image. Pixels inside two thresholds are set to the high value, others to the low value.
><	Creates a binary image. Pixels outside the range of two thresholds are set to the high value, others to a low value.
==	Creates a binary image using the equal operator.
!=	Creates a binary image using the not equal operator.

See Also:

eyes