Abstract: A three-dimensional optical inspection system reconstructs a three-dimensional image of the shape of the surface of an at least partially specular object resident on a printed circuit board by capturing two or more two-dimensional images of the object under different illumination configurations. The diffuse reflection, as well as the specular reflection can be used to reconstruct the three-dimensional image using any reconstruction method, such as photometric stereo. The different illumination configurations can be achieved using an illumination source including light-emitting elements arranged in concentric circular arrays, in which each of the circular arrays is divided into sections. Each section is independently controlled to selectively activate the sections to illuminate the object in a pre-established illumination pattern.

Abstract: An inspection method utilizing vertical slice imaging. A number of horizontal slice images, extending through an object of interest, are acquired. A vertical region of interest is defined from the data representing the horizontal slice images. A vertical slice image is constructed based upon the horizontal slice image data falling within the vertical region of interest. The vertical slice image data may be analyzed to detect defects. In addition, a method is provided to detect defects in a BGA joint. The method includes locating a center of the joint. The method may further include measuring a number of diameters through the center of the joint and applying a rule to compare the measured diameters to an expected diameter.

Abstract: A method and system of object classification uses measurements for a training set of objects to classify an unknown object as being a member in one of several classes of the training set. The classes are defined by features of the training set, the objects of which have known class memberships. The method comprises performing principal component analysis on the training set measurements to discard features that have negligible information regarding class membership, conducting projection pursuit on the remaining training set measurements to accentuate differences between the classes, estimating a distribution of each accentuated class in the training set, and evaluating measurements of the unknown object to determine the membership of the unknown object in one of the accentuated classes. The system implements the method in a computer program stored in computer memory.

Abstract: In a substrate inspecting apparatus comprising a projecting section (4) in which light sources (8), (9) and (10) are provided for emitting colored lights of R, G and B in directions having different elevation angles, one or two color components which is/are greater than the mean value of the intensities of color components is/are extracted for an inspecting region including a soldered portion. Inclined surfaces adapted to the light sources (8), (9) and (10) are converted into monochromatic shaded images by the extraction processing. A boundary position between the inclined surfaces adapted to the light sources (8) and (9) are converted into one shaded image having a mixed color of red and green and the boundary position between the inclined surfaces adapted to the light sources (9) and (10) is converted into a different shaded image.

Abstract: An apparatus and method for detecting characteristics of a microelectronic substrate. The microelectronic substrate can have a first surface with first topographical features, such as roughness elements, and a second surface facing opposite from the first surface and having second topographical features, such as protruding conductive structures. In one embodiment, the apparatus can include a support member configured to carry the microelectronic substrate with a first portion of the first surface exposed and a second portion of the second surface exposed. The apparatus can further include a topographical feature detector positioned proximate to support member and aligned with the first portion of the first surface of the microelectronic substrate to detect characteristics, such as a roughness, of the first surface while the microelectronic substrate is carried by the support member.

Abstract: A screen printing apparatus prints cream solder through a pattern hole of a mask plate, to which a substrate is brought into contact, by sliding a squeegee head. A three dimensional detector, such as a laser, is used to determine the extent to which the pattern hole is filled with the cream solder. Based on the determination result, the printing operation is modified, with respect to the positioning of the mask plate and substrate, to maintain the printing quality.

Abstract: An apparatus and method for inspecting parts. The apparatus includes an x-ray source for illuminating a part from a plurality of locations with respect to the part and an imaging detector for forming a plurality of measured x-ray images of the part, one such measured x-ray image corresponding to each of the illumination locations. A controller compares each of the measured x-ray images with a corresponding calibration image. The controller provides a defective part indication if one of the measured x-ray images differs from the corresponding calibration image by more than a threshold value in part of the measured x-ray image. The controller localizes defects on the part by comparing two or more of the measured x-ray images with two or more corresponding calibration images. The calibration images can be constructed from measured images of defect free parts.

Abstract: A method of analyzing an image of a substance deposited onto a substrate, the image comprising a plurality of pixels, includes defining a region of interest in the image, associating the region of interest with first and second perpendicular axis, wherein a set of pixels in the image lie along the first axis, converting the pixels in the region of interest to a single dimensional array aligned with the first axis and projecting along the second axis, and applying at least one threshold to the single dimensional array, the threshold based at least in part on a predetermined limit.

Abstract: A method of inspecting a stencil having apertures through which a substance is deposited onto an electronic substrate includes depositing the substance through the stencil and onto the substrate, capturing a first image of the stencil after the deposit of the substance and detecting variations in texture of the substance in the first image, capturing a second image of the electronic substrate having the substance on its surface and detecting variations in texture of the substance in the second image, defining a region of interest in the first image and in the second image to determine whether at least one feature exists in the region of interest, measuring a first span of the at least one feature in the region of interest in the first image and a second span of the at least one feature in the region of interest in the second image, and correlating the first span of the at least one feature and the second span of the at least one feature to determine whether a threshold span of the at least one feature has bee

Abstract: The invention relates to an apparatus for visually inspecting soldered joints made on a soldered object, comprising: A camera for recording at least one image of the soldered object on which the soldered joints to be soldered are present, a computing device connected to the camera for receiving the signals from the camera that represent the images recorded by the camera, the computing device being arranged for comparing the signals with signals which are representative of correct soldered joints, and a handling device for moving the soldered objects on which the soldered joints to be inspected have been made to a position within the viewing range of the camera.

Abstract: A method of analyzing an image of a substance deposited onto a substrate, the image comprising a plurality of pixels, includes defining a region of interest in the image, associating the region of interest with first and second perpendicular axis, wherein a set of pixels in the image lie along the first axis, converting the pixels in the region of interest to a single dimensional array aligned with the first axis and projecting along the second axis, and applying at least one threshold to the single dimensional array, the threshold based at least in part on a predetermined limit.

Abstract: A method is provided that allows a simple and inexpensive apparatus to measure the uniformity of the height-directional positions of spheres or hemispheres such as bump electrodes of a semiconductor device. The degree of focus is calculated from an image of bump electrodes 11a and 11b acquired at a first focusing position F1 using an imaging system. After that, the bump electrodes 11a and 11b and the imaging system is relatively moved closer or farther, and then the degree of focus is calculated from an image acquired at a second focusing position F2. The degrees of focus at these two focusing positions F1 and F2 are compared with each other. As a result, detected are the contour lines of the horizontal cross sections of the bump electrodes 11a and 11b at the height (F1+F2)/2 of the position of equal degree of focus indicated by PQ. On the basis of the shapes and/or sizes thereof, the height-directional positions of the bump electrodes 11a and 11b are measured.

Abstract: An apparatus and method for detecting characteristics of a microelectronic substrate. The microelectronic substrate can have a first surface with first topographical features, such as roughness elements, and a second surface facing opposite from the first surface and having second topographical features, such as protruding conductive structures. In one embodiment, the apparatus can include a support member configured to carry the microelectronic substrate with a first portion of the first surface exposed and a second portion of the second surface exposed. The apparatus can further include a topographical feature detector positioned proximate to support member and aligned with the first portion of the first surface of the microelectronic substrate to detect characteristics, such as a roughness, of the first surface while the microelectronic substrate is carried by the support member.

Abstract: Perspective viewing inspection system comprises a stage for holding a printed circuit board (PCB) mounted with electronic parts, teaching means for teaching position data and pose data of the PCB during inspection and also part electrode's addresses on the PCB, means for making an inspection program including layout of inspection areas, means for imaging the inspection areas of the PCB, means for evaluating part-mounting and soldering quality or means for displaying images captured therewith, and means for coordinating the whole system operations. The means for imaging involves an active vision system consisting of an active mirror, an active objective, an ocular, a zoom leans, and an imaging device enabling gaze at solder joints and capture of bird's eye perspective view images thereof. The stage is equipped with a PCB pose controller to orient the PCB at directions wherewith the means for imaging obtains the solder joint's angular perspective view images.

Abstract: To provide a printing inspection apparatus and a printing inspection method enabling an optimal inspection mode in which a balance is kept between the improvement of production efficiency and the securing of a printing accuracy.

Abstract: A method is provided for locating features of an object using varied lighting. An object is illuminated and a first digital image of the object is acquired. An illumination of the object is varied and a second digital image of the object is acquired while a camera and the object are in a same position as the camera and the object were during the acquiring of the first digital image. One of the first and the second digital image is subtracted from another of the first and the second digital image to produce a difference image. At least one feature of the object is located based on the difference image.

Abstract: A system for inspecting a component, such as a die formed on a silicon wafer, is provided. The system includes a two dimensional inspection system that can locate one or more features, such as bump contacts on the die, and which can also generate feature coordinate data. The system also includes a three dimensional inspection system that is connected to the two dimensional inspection system, such as through an operating system of a processor. The three dimensional inspection system receives the feature coordinate data and generates inspection control data.

Abstract: A method and apparatus for inspecting a bump electrode is almost independent of a surface condition of an object to be inspected. Before starting inspection, a template image is prepared by using a predetermined function. During inspection, a gradation correction of the photographed image is made by using a function with a saturation characteristic. The photographed image, which includes an image corresponding to at least one ball, is then segmented. Whether each bump electrode is an acceptable product or not is determined by pattern matching by calculating a normalized correlation coefficient between the segmented image and the template image prepared in advance.

Abstract: A characteristic amount calculating device for soldering inspection. The characteristic amount calculating device includes a design information inputting section for inputting design information of an inspection object, an inspection standard inputting section for inputting an inspection standard, a solder shape calculating section for calculating shape information of a solder fillet according to the design information, and an inspection image calculating section for calculating an inspection image according to the shape information.

Abstract: The invention relates to a method and apparatus for inspecting a substrate having a substance deposited thereon. The steps of the method include depositing the substance onto the substrate; capturing an image of the substrate; detecting variations in texture in the image to determine a location of the substance on the substrate; and comparing the location of the substance with a desired location. The apparatus includes a screen printer that dispenses a substance at a predetermined location on a substrate, and a machine vision inspection system that includes texture based recognition of the substance.

Abstract: The invention provides methods and apparatuses for generating from an image of an object a model of the object, when the object contains similar features. First, the invention finds the similar features. The similar features are found by searching portions of the image for features that are substantially similar to a feature prototype. More particularly, individual features in the image are located and designated candidate features, and optionally a spatial pattern representing a majority of the candidate features is generated. Next, feature profiles are generated therefrom, and the feature prototype is constructed using at least a subset of feature profiles. Thereafter, the model is generated using the similar features and, optionally, the spatial pattern.

Abstract: A bump inspecting apparatus lights a spherical solder bump mounted on the surface of a circuit board and has a reinforcing resin applied to the lower half thereof from all circumferential directions with rays of light which intersect at a predetermined angle. An image of the lighted solder bump is captured while the amount of light irradiated upon the central portion of a solder bump is reduced. An object is extracted from image data obtained by the image capture and the area and/or the aspect ratio of the object are confirmed. The quality of the state of the reinforcing resin applied to the solder bump can be inspected.

Abstract: A system and method for ascertaining blockage of one or more stencil apertures is provided. An analysis of pixels in an image of the stencil region that includes the aperture is made that includes determining the relative grayscale intensity of pixels acquired from the clean stencil and also the variance among nearby pixels. The grayscale and variance values for each pixel are combined to form a series of histogram groupings or bins, based upon levels. These values are used to compute parameters that represent how the apertures appear under the lighting conditions used to acquire the image, thereby allowing the informing of a decision function that estimates the probability that a given pixel represents unblocked aperture rather than solder paste.

Abstract: A circuit board with lead-free solder is inspected by using light sources with different colors at different angles to obtain an image having a plurality of color components. For each pixel within an area in the obtained image, the brightness of a white component generated by mixing all of the color components is extracted. The brightness of each of the color components of each pixel is reduced by an amount corresponding to the extracted brightness of the white component and is adjusted such that the brightest of the color components becomes more strongly emphasized compared to the others, than the brightness before the brightness-reducing process was carried out and the loss in total brightness caused by the brightness-reducing process is restored. The image with restored brightness is displayed and the surface condition of the solder is judged on the basis of the distributions of the color components of this image.

Abstract: Methods and an apparatus are disclosed for providing enhanced vibration immunity in a solder paste inspection system, although they are usable in any number of industries that require rapid acquisition of several images. The method includes capturing at least three images on a frame transfer CCD array before any data is sequentially read from the array. The present method is extendable to a larger number of images. Additionally, the masked memory area can be larger than the image area of the frame transfer CCD array.

Abstract: In an apparatus for inspecting cream solder on a PCB, a camera captures an image of cream solder coated on the upper surface of the PCB. A first illuminator illuminates the cream solder such that the light reflected from an edge of the-cream solder, forming an angle with respect to the upper surface of the PCB, proceeds toward the camera. A second illuminator illuminates the cream solder such that the light reflected from the upper surface of the cream solder, parallel to the upper surface of the PCB, proceeds toward the camera. A controller controls the camera, the first and the second illuminators, and for processing the image captured by the camera into a binary image.

Abstract: A property of the surface such as height is sensed as a function of position on the surface. A statistical spread in the sensed property as a function of the position is computed. Regions where the material is present are distinguished from other regions on the basis of the spread, e.g. conductor tracks on a PCB assembly are distinguished from a PCB substrate by having lower spread.

Abstract: A method and system are provided for inspecting electronic components mounted on printed circuit boards utilizing both 3-D and 2-D data associated with the components and the background on which they are mounted on the printed circuit board. Preferably, a 3-D scanner in the form of a solid state dual detector laser images the components and solder paste on the printed circuit board to obtain the 3-D and 2-D data. Then, a high speed image processor processes the 3-D data to find the locations of the leads and the solder paste. Then, the high speed image processor processes the 2-D data together with the locations of the leads and the solder paste to distinguish the leads from the solder paste. The high speed image processor may calculate centroids of feet of the leads, average height of the feet and border violation percentage of the solder paste.

Abstract: A high-speed image acquisition system includes a source of light; a sensor for acquiring a plurality of images of the target; a system for determining relative movement between the source and the target; and an image processor for processing the acquired images to generate inspection information relative to the target. The system has an extended dynamic range provided by controlling illumination such that the plurality of images is acquired at two or more different illumination levels. In some embodiments, the high-speed image acquisition system is used to perform three dimensional phase profilometry inspection.

Abstract: A method of inspecting an image to locate a ball grid array surface-mounted device includes the steps of inspecting the image to find its surface features and to determine their locations (referred to herein as their “observed” locations); comparing expected locations of those features with the observed locations to identify missing surface features; reinspecting the image in the vicinity of apparently missing surface features to verify if the feature is really missing or to find those features and to determine their “observed” locations; and determining, from the observed locations of the surface features, the position and/or angle of the ball grid array surface-mounted device. The invention can be used to determine the position and/or angle of ball grid array surface-mounted devices with surface features in any of many array configurations, e.g., a regular lattice, a checker board lattice, a reverse checker board lattice, a regular lattice with a holes., and a custom lattice.

Abstract: A computer implemented software device for estimating background tilt and offset is disclosed to preferably be adaptable to an optical measurement instrument wherein the estimated parameters are resolved to generate a reference plane to be subtracted from a height map of a phase profile. A set of histograms of heights is used to develop a merit function. A two-dimensional high speed iterative search is used to optimize the merit function to generate a reference plane coincident with the spatial tilt of the phase profile. The invention enables real-time measurement of substrate height for preferred use in high-speed image processing operations relating to circuit-board production lines.

Abstract: A bump inspection apparatus for inspecting shapes of a plurality of bumps each having a planar top portion, on an inspection object, comprising an illumination optical system for illuminating the top portions with a vertical parallel pencil of light through a telecentric optical system, an observation optical system using a telecentric optical system having an optical axis thereof in conformity with that of the illumination optical system, an observation portion for observing the images of the top portions through the observation optical system in a predetermined range of the inspection object, and a processing portion for analyzing the shapes of the bumps on the basis of the images of the top portions by the observation portion, wherein the processing portion includes analyzing means for analyzing the areas of the planar top portions for the individual bumps and judging means for judging whether or not the rears of the top portions are within a predetermined range.

Abstract: A defect inspection system according to the present invention comprises image acquiring section for acquiring a two-dimensional image of a subject which is a processing target in a manufacturing process, defect extracting section for extracting a defect by a defect extraction algorithm using a predetermined parameter for an image acquired by the image acquiring section, displaying section for displaying an image of a defect of the subject extracted by the defect extracting section, parameter adjusting section for adjusting the parameter in accordance with a defect extraction degree for the subject, and quality judging section for judging the quality of the subject based on a defect information extracted by the defect extracting section.

Abstract: A method for analyzing image data is disclosed that will find defects on a multi-layer device having solder pads, such as a semiconductor computer chip. The method provides a device template image, a theoretical image created from data from several real images, for comparison to an image of a device to be tested after the solder pad data is segmented. The parameter values of the device to be tested are recorded and compared to the parameter values of the device template, forming a difference image. The difference image and the solder pad data are then run through a series of tests, wherein the device is determined defective or not defective.

Abstract: An image of an actual pattern of discrete objects is analyzed with respect to a model representing a predefined ideal pattern of objects. Initial processing is performed on only a portion of the image associated with ones of the objects located in an original neighborhood within the image to determine information about an affine transformation of the actual pattern of the discrete objects relative to the predefined ideal pattern. Additional processing is performed on other portions of the image based on the results of the initial processing. Initial processing is performed with respect to a first part of the image by operating on only a first portion of all of the digital data that represents that first part of the image.

Abstract: An integrated X-ray and visual inspection system having an inspection subsystem with a holder holding an object to be inspected, an X-ray source, a camera receiving an X-ray image of an object to be inspected and a camera receiving a visible image of an object to be inspected, the X-ray source and camera receiving the X-ray image being positioned on opposite sides of the holder. A display may also be provided for displaying the images. The system is well suited to the inspection of printed circuit boards having electronic components mounted thereon, in which case the holder may be a conveyor for the printed circuit boards. Independent positioning of the X-ray source and camera receiving the X-ray image allows offset images of the printed circuit board topside and bottomside features of the board. Various other features of the system and methods are disclosed.

Abstract: Inspection of solder paste on a printed circuit board using a before printing image (pre-application image) to normalize an after printing image (post-application image) of the printed circuit board. Existing lighting and optics used for alignment of the screen-printing stencil to the printed circuit board are used for the solder paste inspection. An embodiment is described wherein pad regions of the printed circuit board are inspected for information about the solder paste applied on the pad regions of the printed circuit board. A stencil in the screen printing process is also inspected using a before printing image (pre-application) to normalize an after printing image (post-application) of the stencil.

Abstract: A solder testing apparatus comprising image processing means for performing image processing on an image of an appearance of a soldered portion to identify shape characterizing amounts for the soldered portion; and defect determining means for performing good/bad determination on the soldered portion from data derived by the image processing means and data from test parameter storing means for storing shape characterizing amounts at design time, wherein tested-object standard shape estimating means is included for extracting shape characterizing amounts of a non-defective soldered portion by statistically processing shape characterizing amounts for soldered portions identified by the image processing means, and defect determining parameters stored in the test parameter storing means are updated based on standard shape values from the tested-object standard shape estimating means, so that a highly reliable test is realized by setting defect determining parameters based on actual shapes and dimensions of leads

Abstract: A method for measuring such parameters as height, position, shape, colinearity, and coplanarity of arrays of minute objects on the surface of integrated circuits, such as Ball Grid Arrays (BGA), all in one simple and straight forward procedure during the manufacturing process of integrated circuits. Shadows of the objects are created on the substrate through the use of x-rays or other light sources placed at predetermined distances and angles from the objects. An imaging device obtains images from the shadows cast onto the substrate and the images are then analyzed to determine if they meet predefined parameters. Multiple sources of illumination can be used to illuminate the array in order to create a more precise image for analysis and three dimensional images of the BGA can be created for analysis.

Abstract: An inspecting apparatus is arranged on an electronic component mounting line for inspecting whether a mounting state of the component mounted on a printed circuit board by a mounting apparatus in a precedent process or a printing state of a cream solder by a cream solder printing apparatus in a precedent process is non-defective or defective.

Abstract: A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid.

Abstract: An arrangement of discrete objects is analyzed. First and second characteristics are extracted from an actual arrangement of discrete objects and an ideal arrangement of points, respectively, and the first and second characteristics are compared. Each characteristic is invariant, to within an angular constant, under an affine transformation of the respective arrangement.

Abstract: An image of an actual pattern of discrete objects is analyzed with respect to a model representing a predefined ideal pattern of objects. Initial processing is performed on only a portion of the image associated with ones of the objects located in an original neighborhood within the image to determine information about an affine transformation of the actual pattern of the discrete objects relative to the predefined ideal pattern. Additional processing is performed on other portions of the image based on the results of the initial processing. Initial processing is performed with respect to a first part of the image by operating on only a first portion of all of the digital data that represents that first part of the image.

Abstract: A computer implemented software device for estimating background tilt and offset is disclosed to preferably be adaptable to an optical measurement instrument wherein the estimated parameters are resolved to generate a reference plane to be subtracted from a height map of a phase profile. A set of histograms of heights is used to develop a merit function. A two-dimensional high speed iterative search is used to optimize the merit function to generate a reference plane coincident with the spatial tilt of the phase profile. The invention enables real-time measurement of substrate height for preferred use in high-speed image processing operations relating to circuit-board production lines.

Abstract: Disclosed is an apparatus and method for inspecting a connection state of a lead electrode to a bump after TAB (tape automated bonding). An LSI chip is immobilized on a stage. A flexible lead is held by a holding portion and connected to a bump. Above the chip, a CCD camera is provided. The stage is controlled to move up and down by a moving control mechanism. Each of the lead/bump connection states immediately after ILB (Inner lead bonding) is taken in the form of image data and defined as a first image data. A second image data of the lead/bump connection state is taken after the bump and lead are moved to different positions by moving the stage in order to change the position of the chip by means of the moving control mechanism. Whether or not the lead is duly connected to the bump is determined by the comparison of the first and second image data.

Abstract: A method of inspecting an image to locate a ball grid array surface-mounted device includes the steps of inspecting the image to find its surface features and to determine their locations (referred to herein as their "observed" locations); comparing expected locations of those features with the observed locations to identify missing surface features; reinspecting the image in the vicinity of apparently missing surface features to verify if the feature is really missing or to find those features and to determine their "observed" locations; and determining, from the observed locations of the surface features, the position and/or angle of the ball grid array surface-mounted device. The invention can be used to determine the position and/or angle of ball grid array surface-mounted devices with surface features in any of many array configurations, e.g., a regular lattice, a checker board lattice, a reverse checker board lattice, a regular lattice with a holes, and a custom lattice.

Abstract: A solder joint inspection process and system includes using a correlation values to classify the shape of the solder joint. The solder joint is illuminated by a multiple colors, and the image of the solder joint is captured. This multiple color image is then converted into a plurality of one-dimensional vectors. Each one-dimensional vectors sequence is for one color of the multi-color illumination and for a one-dimensional spatial extent. Correlation values among all combinations of the one-dimensional vector sequences are computed and used for training an automatic solder joint shape classifier.

Abstract: An apparatus and method are provided for automatic visual inspection of crescent-shaped wire bonds. The apparatus includes image acquisition means for acquiring an image of a wire and an image of a crescent-shaped wire bond. A search model is used that includes a crescent-modeling portion, and can also advantageously include a wire modeling portion. Search functionality is used to find an image of the crescent-shaped wire bond, using the search model, so as to provide location information regarding the location of the crescent base, and shape-match information regarding the reliability of the found location information. The invention is useful for verifying the correct position of the crescent bond to ensure good electrical contact. In addition, the invention greatly simplifies the task of two other important automated visual inspection steps: wire location and crescent shape determination. Presence/absence of the crescent bond can also be determined using this information.

Abstract: An inspecting apparatus is arranged on an electronic component mounting line for inspecting whether a mounting state of the component mounted on a printed circuit board by a mounting apparatus in a precedent process or a printing state of a cream solder by a cream solder printing apparatus in a precedent process is non-defective or defective.

Abstract: A method for determining spatial characteristics of a selected object in an image that has pixel values representing heights of corresponding portions thereof is characterized by the steps of finding one or more heights of portions of the object, determining a volume of the object at and above (or below) a selected height by summing a count representing a cross-sectional area of the object at that height with a count representing a volume of the object at a greater (or lesser) height, and outputting the volume so determined. A related method determines a cross-sectional area of an object in such a "height" image by finding one or more heights of portions of the object and summing a count of pixels in the object at the selected height with a count representing a cross-sectional area of the object above that height.