A histogram counts and graphs the total number of pixels at each grayscale level. From the graph, you can tell whether the image contains distinct regions of a certain gray-level value. A histogram provides a general description of the appearance of an image and helps identify various components such as the background, objects, and noise. A line profile plots the variations of intensity along a line. It returns the grayscale values of the pixels along a line and graphs it.
The line profile utility is helpful for examining boundaries between components, quantifying the magnitude of intensity variations, and detecting the presence of repetitive patterns. Thresholding segments an image into a particle region, which contains the objects under inspection, and a background region based on the pixel intensities within that region. The resulting image is a binary image. The user sets a particular pixel value as the threshold, and any pixel value below the threshold will be replaced by a pixel value of 0, and any pixel value equal to or above the threshold will be replaced by a 1 or a user-specified value.
A binary image is an image containing particle regions with pixel values of 1 and a background region with pixel values of 0. Binary images are the result of the thresholding process. Because thresholding is a subjective process, the resulting binary image may contain unwanted information, such as noise particles, particles touching the border of images, particles touching each other, and particles with uneven borders.
By affecting the shape of particles, morphological functions can remove this unwanted information, thus improving the information in the binary image. Binary morphological operations extract and alter the structure of particles in a binary image.
You can use these operations during your inspection application to improve the information in a binary image before making particle measurements, such as the area, perimeter, and orientation. Basic morphology operations include erosion, dilation, open and close. Edge detection is an effective tool for many machine vision applications. It provides your application with information about the location of object boundaries and the presence of discontinuities. The discontinuities are typically associated with abrupt changes in pixel intensity values that characterize the boundaries of objects in a scene.
Golden template comparison compares the pixel intensities of an image under inspection to a golden template. A golden template is an image containing an ideal representation of an object under inspection.
A pixel in an inspection image is returned as a defect if it does not match the corresponding pixel in the golden template within a specified tolerance. NI Vision Concepts Help. Open a service request. You can find the include files under the include subdirectory. Please refer to the readme. These programs are installed in the sample subdirectory under the target installation folder, if you elected to install the sample files.
The generic and high-level functions appear within each function class in the logical order you might need to use them. The low-level functions appear within each function class in alphabetical order.
Use high-level functions to quickly and easily capture images. If you need more advanced functionality, you can mix high-level functions with low-level functions. Snap functions capture all or a portion of a single frame or field to the user buffer. Grab functions start a continuous image acquisition to a user buffer. Any frame or field can be copied from the grab buffer to another user buffer.
Use low-level functions when you require more direct control of the acquisition of the images. Use acquisition functions to configure, start, and abort an image acquisition, or examine a buffer during an acquisition. Use utility functions to display an image in a window, save an image to a file, or to get detailed error information.
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The following conventions are used in this manual: » The » symbol leads you through nested menu items and dialog box options to a final action. This icon denotes a note, which alerts you to important information. Bold text also denotes parameter names. This font also denotes text that is a placeholder for a word or value that you must supply. This font is also used for the proper names of disk drives, paths, directories, programs, subprograms, subroutines, device names, functions, operations, variables, filenames and extensions, and code excerpts.
Contents Introductory Programming Examples SYS Figure Table Generic Functions Use generic functions in both high-level and low-level applications. Snap Functions Snap functions capture all or a portion of a single frame or field to the user buffer.
Grab Functions Grab functions start a continuous image acquisition to a user buffer. Call this function only after calling imaqSetupGrab. Chapter 2 Software Overview Sequence Functions Sequence functions start and stop a continuous acquisition of multiple frames. Miscellaneous Functions Miscellaneous functions return information such as session status. Low-Level Functions Use low-level functions when you require more direct control of the acquisition of the images.
Acquisition Functions Use acquisition functions to configure, start, and abort an image acquisition, or examine a buffer during an acquisition. Chapter 2 Software Overview imaqStopAcquisition Stops an asynchronous acquisition or synchronous continuous acquisition immediately.
Chapter 2 Software Overview Utility Functions Use utility functions to display an image in a window, save an image to a file, or to get detailed error information. You can only view or download manuals with. Sign Up and get 5 for free. Upload your files to the site. You get 1 for each file you add. Get 1 for every time someone downloads your manual. Buy as many as you need.
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Text in this font denotes text or characters that you should enter from the. This font is also used for the proper names of disk drives, paths, directories,. Italic text in this font denotes text that is a placeholder for a word or value.
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