Vision Components From One Source | Saber1 Technologies LLC

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Key Terms

A
Accuracy	The measurement accuracy with a vision system cannot be described simply like a general-purpose measuring instrument. All possible related conditions should be considered, such as optical factors (resolution, distortion, magnification, and aperture ratio of the lens), the pixel resolution according to the CCD size, processing algorithm, and image-capturing conditions (illumination and moving speed of targets).
AGC Circuit	The circuit built into the camera. The AGC circuit automatically controls the amplification factor to maintain video signals at a constant output level.
Analog Signal	Any continuously variable signal.
Angle of View	The angle that indicates the relationship between the available field of view and the working distance. In other words, the angle of view is determined by the size of the CCD and the focal length of the lens. A wide-angle lens has a wider angle of view; a telephoto lens has a narrower angle of view.
ASIC	Application Specific Integrated Circuit. This is an integrated circuit that is designed and manufactured for specific applications. It is also called a custom IC or custom chip. There are two types of ASICs: Full-custom ICs, where all circuits are specially designed, and semi-custom ICs, which are designed by combining several circuit blocks with specific functions and then modifying the circuitry of the "semi-finished product" according to the specifications.
Aspect Ratio	The length-to-width ratio of a monitor's display.In Japan, monitors conform to the NTSC system so that the aspect ratio is represented as "4 (H) : 3 (V)". Consequently, cameras are also designed according to this ratio. The PAL and SECAM systems, used primarily in European countries, also use the same aspect ratio.
Average	Processing that removes noise in image data. The brightness of the target pixel is replaced with the average brightness of the target pixel and its neighboring eight pixels. The effect is stronger than with Median processing because noise data is also used for the average calculation.
B
Back Focal Length	The distance between the back surface of a lens and the point at which parallel light passing through the lens is converged (focal point).
Background Image	A process used to reduce the effects of non-uniform illumination, image mottle, stray light, and some camera defects. Often performed on the live video image prior to processing. Can also be used to display motion as a difference between two images. The image to be subtracted from an acquired image during background subtraction. Usually this image is taken from part of the slide that contains no sample defocused. If defocused is used, setup Koehler illumination before taking the background image.
Base Configuration	The simplest and most common form of CameraLink™. This uses one cable supporting up to 255 Mbytes/sec.
Binary Image	An image consisting of pixels that are processed using binary processing. Binary images are used for presence/absence detection as well as the measurement of area, position, or angle. Processing time is short because the information for each pixel of a binary image (2 levels) is significantly less than that for a shade-scale image (256 levels).
Binning	The process of combining data from multiple pixels (e.g. 2x2 regions) into a single pixel during acquisitioning. Binning the original image causes the resulting image to be brighter and smaller, but the resolution will be lower as a result. Because the image is smaller, the time required to transfer the image and the memory storage requirements will be significantly reduced.
Bit Depth	The number of bits used to encode the intensity values in an image. The greater the depth the more different values which can be distinguished. Sometimes called bit depth.
Blooming	A phenomenon where the edges of an image appear blurred when the CCD is exposed to extremely bright light. This is because the light fills up a pixel with charge and then overflows to neighboring pixels as well. For structural reasons, the electricity charged on the CCD easily leaks in a vertical direction. As a result, the light also spreads in a vertical direction so that strong blooming creates round spot light appears as an ellipse.
Brightness	(1) Gray level for displaying pixels in an image. In analog video devices, sometimes called offset. Increasing the brightness will increase the amount of light used to display pixels of every valve. (2) The luminosity of each pixel. In a shade-scale image (256 levels), for example, the lowest brightness, value "0" is black and the highest, value "255" is white.
C
C-Mount	The JIS standard lens mount used to attach a lens to a camera. It is specified with a flange back of 17.526 mm and screw of "1" 32 UNF.
CameraLink™	A high speed interface between cameras and computers specifically designed for the vision industry. Allows data rates up to 680 Mbytes/sec (over 5 Gbits/sec), and uses dedicated signals for real time control.
CCCD	Cooled Charge Coupled Device. Cooling reduces the noise generated by the silicon chip (so called "dark noise"), this is particularly important for low light level conditions.
CCD	Charged Coupled Device, a type of camera that uses an array of silicon chips, which collect charge in a well that is then transferred to generate the signal.
CCD Trigger	A function that samples a part of an image and initiates shutter operation when the sample image changes. This method is convenient because an external sensor for synchronization is unnecessary. However, it is not suitable for high-speed production lines because the response speed is generally slower than the sensor.
CCTV Lens	The lens is mainly used for monitoring cameras (CCTV: Closed Circuit TV). The CCTV lens is the most common lens used for the camera in the vision system.
CL	CameraLink™. The CameraLink™ is a digital camera output standard. See EIA web site to get more information.
Clipping	A result of over saturation (too bright) or under saturation (to dark) in an image. If the video image contains grayscale values outside the image processor's upper and lower limits for the grayscale range, pixels exceeding the limits are set to the highest or lowest values possible.
Close-Up Adapter	An accessory used to bring a lens closer to a subject than its closest focusing distance. The close-up adapter provides some distance between the lens and the camera. Using a close-up adapter by adjusting its thickness sometimes achieves a clear focus for a shorter distance that is not in the lens specifications. It is necessary to use an actual adapter for adjustment because the thickness and working distance vary depending on the lens specifications and individual differences.
Closest Focusing Distance	With CCTV lenses, this is the closest distance between a subject and a lens at which clear focus is obtained. To obtain further close-up images, a close-up adapter is required.
Color Temperature	The value that represents the color of a light source, measured in units of K (Kelvins). When an ideal black body is heated, it gradually emits a reddish light. When the temperature rises, the color of the light changes to yellow, white, and finally blue. The color temperature indicates the temperature of a black body when the light of respective colors is emitted. Reference values:Daylight (sunny): Approx. 5, 500 K, Sunrise or sunset: Approx. 2, 500 K, Light of household electric bulb: Approx. 2, 800 K, Candle light: 1, 900 K.
Contrast	The gray level variation within an image. In analog video devices sometimes referred to as gain. Increasing the contrast makes the change in displayed gray level increase relative to change in pixel value.
D
Dark Current	The flow of electricity of video signals when a camera receives no light. It is optimal if the dark current is as low as possible because it usually increases to some extent when the ambient temperature rises.
Depth of Field	The range of the position of a subject between the closest and the farthest from the lens surface that provides clear focus. The depth closer to the lens side is called the front depth of field; the one farther from the lens is called the back depth of field. The depth of field has the following characteristics: (1) The higher the F-stop number the larger the depth of field. (2) The shorter the focal length of a lens the larger the depth of field. (3) The farther the distance from a subject the larger the depth of field. (4) The back depth of field is larger than the front depth of field.
Digital Camera	Camera with its own board that communicates with the computer digitally rather than producing and analog video signal, which would then be "grabbed" by a video board. Generally, digital cameras offer higher spatial resolution, and more dynamic range than video cameras.
Digital Signal	A signal's that is both discrete and quantized.
Digitizer	A computer component utilizing an Analog to Digital converter, which is used to take video images and convert them into digital format for use on a computer.
Dongle	Means of copy protecting programs using a piece of hardware. Programs will only run if the correct key is attached to the parallel port of the computer. Sometimes called a Memory Key.
DSNU	Dark Signal Non Uniformity. The DSNU characterizes the uniformity of dark signal. It's value depends on temperature (doubling every 8°C temperature increase) and integration time.
Duel Base Configuration	This refers to a CameraLink™ Frame Grabber than can support two Base Configuration cameras simultaneously.
DVAL	Data VALid. Used in CameraLink™ standard. When DVAL is active the output pixel are valid.
Dynamic Range	The range of gray values, from lowest to highest, found in an image.
E
Edge Extraction	Processing that detects edges at which the brightness of an image greatly changes (high-frequency components) and converts them into white. The area other than the edges is converted into black.
F
F-Mount	Nikon® lens mount. The F mount is the lens mount standard defined by Nikon®.
F-Stop Number	A unit that indicates the amount of light passing through a lens. The F-stop number is expressed as a reciprocal number of the aperture ratio, which is obtained by dividing the focal length of the lens by the diameter of the aperture. Generally, the lower the F-stop number, the more light is let in through the lens. This may not always be true depending on the number of lenses in the system or lens coating conditions.
FFC	Flat Flied Correction. The FFC may be use to correct DSNU, PRNU or light source non-uniformity.
FFT	Fast Fourier Transform. A command used to remove or enhance patterns of periodic "noise" in an image.
Fiber Light	A light source that guides the light of a halogen lamp along a fiber made of quartz or plastic. A fiber light is easy to use because the light is extremely bright and adjustable and the intensity fluctuation due to the ambient temperature is low.
Field	A unit that makes up a frame. In interlaced scanning, there is an odd-numbered field created by scanning only odd-numbered lines, and an even-numbered field created by scanning only even-numbered lines.
Field of View	The area visible through the microscope.
Filter Wheel	A device for exchanging filters in the light path of a microscope. Some are computer controllable (e.g. The Sutter Lamda 10). Typically filter wheels are used let specific wavelength pass to (excitation wavelength) the preparation or coming from (eemittancewavelength) the specimen.
Fluorescence	Property of certain molecules that the will emit light at frequency other than the frequency they absorb. This property is especially useful in biology due to indicator dyes whose amount of fluorescent change under certain conditions, typically calcium concentration, acidity (ph) or voltage.
Focal Length	The distance between the point at which parallel light passing through a lens is converged (focal point) and the central point of the lens on the optical axis (principal point). A wide-angle lens has a short focal length so its field of view is wide even with a short working distance. On the contrary, a telephoto lens has a long focal length so images can be captured in a narrow field of view with a long working distance.
Focal Point	The point at which parallel light passing through a lens is converged. The focal point on the side of a subject is called the front (subject-side) focal point; the one on the side of the image pickup element is called the back (image-side) focal point. When used alone, the term "focal point" generally refers to the latter type.
Frame Grabber	Camera interface card for a computer.
Full Configuration	This is a two cable implementation of CameraLink™ supporting up to 680 Mbytes/sec.
FVAL	Frame VALid. Used in CameraLink™ standard. When FVAL is active the output pixel are valid.
G
Gain	The amount of amplification that an analog signal receives. For video, gain is used to increase or decrease the dynamic range of a video camera by selecting the voltage levels that the digitizer will accept. For example, when viewing a faint image, the gain is often raised to increase the minute changes into those that are more readily detectable.
Grayscale Image	Synonymous with a shade-scale image. Like images on a black-and-white TV, a grayscale image is represented by the brightness of each pixel, generally with 8 bits (256 levels) per pixel.
Grayscale Value	The brightness of pixels in a digitized image. By convention, the grayscale values of an 8-bit digital signal, with 2 to 8th (i.e. 256) possible values, range from 0 (black) to 255 (white).
H
HAD	Hole Accumulation Diode. HAD is a photo-diode with a very low lag level and high quantum efficiency.
Histogram	A graph of the number of counts per value in a data set.
Horizontal Resolution	The number of pixels in an image in a horizontal direction.
Horizontal Synchronization Signal	A signal that indicates the beginning of the scanning of a screen in a horizontal direction. During each horizontal retrace line period of a video signal, horizontal synchronization signals are inserted as pulse signals of opposite polarity to the brightness signal that indicates the brightness information of the subject. This signal is sometimes abbreviated as H-SYNC.
HSI	A method for storing and displaying color information about an image. A separate (usually 256 level) value is kept for each parameter, Hue (color), Saturation (purity of color) and Intensity (brightness).
Hue	One of the three attributes of color used to represent colors quantitatively. Hue represents the tone of a color, or the difference in wavelength such as red, green, or blue.
I
Image Compression	A method used to reduce the size of image data. Image data consists of a significant amount of data. Since such a large amount of data is difficult to save or transmit, image compression is used to reduce the size of the data while maintaining all the necessary information. JPEG and MPEG are two widely used image compression methods.
Image Processing	(1) The application of signal processing techniques to the domain of images - two-dimensional signals such as photographs or video. (2) The use of processing functions to improve the visual display of an image.
Integration	Bringing together of things.
Interlaced Scanning	A scanning method used to convert the analog image formed on the CCD into digital signals for output. Scanning begins at the upper left corner of the screen and when the scanning reaches the right edge, it skips the next line and starts again on the line below the skipped line. The image obtained by scanning only odd-numbered lines is called an odd-numbered field; the image obtained by scanning only even-numbered lines is called an even-numbered field. Combining these two fields creates the data for one screen (frame). This scanning method is sometimes called 2:1 interlaced scanning because two fields are used to create one frame.
Invert	Processing that inverts the bright and dark areas of an image. With a binary image, white pixels (1) are converted into black pixels (0) and vice versa. With a shade-scale or color shade-scale image, the order of the brightness levels of the original image is reversed so that the area of level 255 is converted into level 0, for example. This processing is used when color setting is difficult because the target is small or has uneven color. Extracting the background color and reversing the image creates an image that has the same data but is easier for the labeling that is required for detecting the center of gravity.
IR	Infra Red. IR is part of the light spectrum with longer wavelength than the visible part. Care must be taken with CCD because often they are sensitive to infra-red light.
J

K
Kernel	A matrix of numbers used for processing an image. The kernel is passed over each pixel in the image. The pixel under the kernel is replaced by the sum of each element in the kernel time the intensity value of the pixel in the same relative position to the pixel being replaced.
L
Linearity	A measure of the accuracy of a camera when used to measure the light levels in an image. For most imaging applications, the ideal camera should have a precisely linear relationship between brightness and grayscale value.
Luminance	Brightness of light, usually measured in candela per square meter or in foot-lamberts.
LUT	Look Up Table, sometimes referred to as a palette, it is used to display colors or gray scales of non-24 bit images. Each intensity value (or range for 16 bit images) is assigned one of the 256 colors listed in the Look Up Table.
LVAL	Line VALid. Used in CameraLink™ standard. When LVAL is active the output pixel are valid.
M
Machine Vision	Capture of the image using cameras optics and lighting and is capable of controlling equipment to respond to the results of processing.
Macro Lens	A type of lens used to obtain enlarged images without using a close-up adapter or close-up lens. This lens is used for a variety of measurements or to obtain magnified pictures of minute targets.
Magnification	A measure of the apparent difference in size between the object and the image of the object.
Medium Configuration	This is a two cable implementation of CameraLink™ supporting up to 510 Mbytes/sec.
Microscopy	Any technique for producing visible images of structures or details too small to otherwise be seen by the human eye using a microscope or other magnification tool.
Monochrometer	Device for changing the wavelength of light. Typically used for excitation light but could be used for both. Also can be used as a shutter. Typically much faster at changing wavelengths than a filter wheel.
N
Non-Interlaced Scanning	Synonymous with all-pixel reading. A method of scanning that converts the analog image on the CCD into digital signals for output. Scanning starts at the upper left corner of the screen and when it reaches the right end, it starts again on the line immediately below. Although it requires twice as much time as interlaced scanning, non-interlaced scanning is suitable for accurate detection because the amount of data is doubled.
Normalized Correlation	The method generally used for search or pattern matching. This theoretically determines a matching rate after adjusting the average brightness values of the template and the input image to the same level. The result is barely affected by the color variation of targets or changes in illumination. The challenge is to reduce the time required for processing a large amount of data.
NTSC	The standard for color TV video signals proposed by the National Television System Committee. This system is widely used in many countries, including the U.S. and Japan. NTSC also specifies rules to ensure compatibility between monochrome and color cameras. NTSC specifies 525 scanning lines, an aspect ratio of 4:3, horizontal scanning frequency of 15.734 kHz, vertical scanning frequency of 59.94 Hz, and a 2:1 interlaced scanning method.
Number of Effective Pixels	The number of pixels that a camera can output as image signals.
O
OCR	Optical Character Recognition. This is the processing used for reading characters such as zip codes on postal mail. OCR compares an input image with a registered image of specific characters. The input image is recognized as a character when the matching rate with the character is highest.
Optical Resolution	A lens is used to project an optical image onto the CCD. The optical resolution refers to the resolution of the lens and is normally represented in units of "lines/mm" or "lp/m". From an optical point of view, an image of lower resolution than the optical resolution is considered to be blurred. When the optical resolution is low, it is useless to enlarge the image to obtain better pixel resolution.
Overlay	(1) Method for changing the display of the image without changing the image data itself. For example regions in MetaMorph are displayed using the overlay so that they are clear to the user but do not affect the data within the image. (2) Memory used to store specific image data. Such data is used to display numerical values, characters, or line drawings that are overlaid on the image on the monitor screen.
Overscanning Monitor	A type of monitor that hides the ringing immediately after blanking and geometry distortion by about 10% of the video signal received from a camera. Most consumer TVs are the overscanning type.
P
Picture Element	The smallest unit that makes up an image, also called a "pixel" or "dot". An image is represented with a systematic arrangement of pixels. The size of image data can be expressed, for example, as either "512 (H) x 480 (V) pixels" or as "a total of 245, 760 pixels".
Pixel	A portmanteau of picture element is one of the many tiny dots that make up the representation of a picture in a computer's memory. A discrete point in an image.
PoCL	A recent addition to the CameraLink™ standard to allow cameras to be powered via the CameraLink™ cable.
Pre-Processing	Processing that converts the original image into an image that can be easily processed for area, shape, or position measurement. Pre-processing is a generic term that includes binary processing, color shade-scale processing. Various types of filters include Expand, Shrink, Average, and Shading.
PRNU	Photo Response Non Uniformity. PRNU characterizes the differences of sensitivity from pixel to pixel.
Pseudocolor	Displaying intensity levels of an image as colors. The human eye is better to pick out changes in color than change in gray level. UIC programs contain a Pseudo-color LUT for this type of display. UIC's LUT is essentially a rainbow plus white at the highest intensities other LUT can and are used for a variety of purposes.
Q

R
Random Shutter	Synonymous with synchronization shutter. A function that releases the shutter at the instant a camera receives a trigger signal input. Standard cameras without the synchronization shutter function use a TV synchronization method, which releases the shutter every 1/60 second based on an internal trigger of the camera. With TV synchronization, an image of a fast-moving target cannot be properly captured due to the operation delay of up to 1/60 second after the trigger input.
Region of Interest (ROI)	A spatial area if an image, which can be delineated using tools in UIC's programs. Sometimes referred to simply as a Region or as a ROI.
Resolution	The ability of a microscope system to image closely spaced points, lines, and objects surfaces as separate entities. A "low" resolution indicates an inability to resolve two close points, lines, or objects surfaces as separate entities. Often confused with the limit of detection (q.v.).
RGB	Red-Green-Blue. A method for storing and displaying color information about an image. A separate value is kept for the intensity of each color, red, green and blue.
S
S/N Ratio	For a camera, the ratio between saturation voltage and noise in darkness. For a vision system, this is the ratio between the output of the rated signal and the output of the state where no light is received. The S/N ratio is indicated in decibels (dB).
SafePower	A protocol used in the Power over CameraLink™ (PoCL) specification which allows powered cameras to be safely disconnected and reconnected.
Saturation	One of the three attributes of color used to represent colors quantitatively. Saturation represents the vividness of a color. With the color red, for example, a red of high chroma is vivid red. When the saturation level decreases, the red becomes moves closer to gray (achromatic color).
Segmentation	The process of deciding whether a pixel is part of an object to be measured of processed, or is merely part of the background and to be excluded from analysis. This process generally uses the grayscale intensity or color values of the pixel to make the decision. For example, you might segment the image by selecting and upper and lower threshold to define a range of acceptable grayscale levels, and the image processor would group all of the contiguous pixels that fall within that range onto "objects".
Sensitivity	A measure of the amount of incident light upon an image sensor required to produce a specified signal at the output.
Shading	An undesired brightness gradient in an image, not present in the original scene, which may be caused by stray light or uneven illumination.
Sharpening	A digital process for making edges more clearly in an image. Sharpening does not actually improve image quality but can make some images seem sharper to the human eye.
Shutter Speed	The exposure time for the image pickup element. Capturing an image of a fast-moving target requires a shorter exposure time (faster shutter speed) to avoid a blurred image. However, a faster shutter speed may cause a darker image due to insufficient exposure. Some adjustments may be required, such opening the lens iris wider.
Signal	A flow of information. Most signals of interest can be modeled as functions of time or position.
Smear	The noise specific to the CCD that is generated while image data is being read from the CCD. CCD is still exposed to light when an image is captured and the data is read from the CCD. If the CCD receives extremely bright light such as a spotlight, streaks of bright, vertical lines may appear on the readout image. This phenomenon is caused by the vertical transmission from the CCD, which transmits the received electricity in succession.
Square Pixel CCD	A type of CCD that consists of pixels with an aspect ratio of 1:1. Conventional pixels previously were rectangular with the ratio of height to width of 1:1.28. As a result, when the dimensions of a square are measured, the resulting width is 100 pixels and the height is 128 pixels. To avoid such errors, conventional vision systems require some correction methods such as changing the sampling frequency when an image is read from the CCD.
Sub-Pixel	Normally, the resolution of dimensional measurement or position detection is represented in units of pixels. Sub-pixels are a way to obtain more detailed values through calculation, or the value obtained by the calculation. A typical method to obtain values in units of sub-pixels is to differentiate the brightness gradient of the area surrounding the target pixel. However, each manufacturer is gaining its own expertise and methods often remain proprietary. To compare performance, it is necessary to pay attention to repeatability and linearity rather than just checking the number of digits of the displayed values.
Synchronization Signal	There are two types of synchronization signals: A horizontal synchronization signal that indicates the beginning of the scanning in a horizontal direction; and a vertical synchronization signal that indicates the beginning of each field of a screen. Synchronization signals are inserted into video signals as pulse signals of opposite polarity to the brightness signal during the retrace line period.
T
T2- Mount	Optical mount: 42 M0.75. T2-Mount is one of the multiple lens mount standard.
Telecentric Lens	This type of lens offers an angle of view of 0 degrees. Thus, the dimensions of a subject barely change even when the subject moves closer to or further from the lens. An image of even a high-profiled subject is seldom affected by parallax. For the measurement of the inner diameter of a pipe, for example, a CCTV lens (especially a wide-angle lens) may cause distortion of the shape or may show the inner wall according to the position of the pipe in the image. However, a telecentric lens causes almost no distortion or shows the inner wall regardless of the position of the pipe in the field of view.
Telephoto Lens	A type of CCTV lens that has a relatively long focal length. Images can be captured in a narrow field of view with a long working distance.
Threshold Value	A reference value used to convert each pixel making up a shade-scale image into binary data. When the target pixel is brighter than the threshold value, it is converted into a white pixel (1); when darker, it is converted into a black pixel (0). In general, the upper and lower limits are specified as threshold values. In such a case, when the target pixel is brighter than the upper limit, it is converted into a black pixel (0); when darker than the upper limit, converted into a white pixel (1); when brighter than the lower limit, converted into a white pixel (1); and when darker than the lower limit, converted into a black pixel (0). The upper value is often fixed to the maximum level (255).
Turnkey	When a separate entity is responsible for setting up a plant or equipment (e.g. trains/infrastructure) and putting it into operations.
24-Bit Color	Method for displaying and recording color images. In the display method each pixel uses its own color values for displaying and a LUT is no longer used. 24 bit displays and images usually contain 3 separate 8-bit channels, Red, Green, Blue (RGB) or Hue-Saturation-Intensity (HSI).
U
Underscanning Monitor	A type of monitor that displays all effective pixels of a camera.
V
VariSpec	A liquid crystal device for controlling the wavelengths of light in the light path of a microscope. Can be very fast and stable.
Vertical Resolution	The number of pixels in an image in a vertical direction.
Vertical Synchronization Signal	A signal that indicates the beginning of each field of a screen. During the vertical retrace line period of video signals, vertical synchronization signals are inserted as pulse signals of opposite polarity to the brightness signal that indicates the brightness information of the subject. This signal is sometimes abbreviated as V-SYNC.
W
White Balance	The adjustment of the balance of RGB signals received with a color camera. Color cameras have subtle individual differences in their sensitivity to received light. White balance compensates these differences by adjusting the balance of RGB signals. Normally, a reference value is obtained using a white paper target illuminated with white light.
Wide-Angle Lens	A type of CCTV lens that has relatively short focal length. A wide-angle lens provides a wide field of view with a short working distance.
Working Distance	The distance between a subject and the lens surface.
X

Y

Z
Z-Position	The position of a point of object in an image up and down in space, relative to a user-defined origin. The X and Y positions refer to "horizontal" and "vertical" positions, while the Z-position refers to position orthogonal to the X, Y plane.