# US 2014/0192234 A1 · Method for generating and evaluating an image

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- Number: US 2014/0192234 A1
- Document ID: US20140192234A1
- Status: Published application
- Kind: A1
- Application number: 14/118,236
- Filed: 2012-05-16
- Published: 2014-07-10
- Earliest claimed: 2011-05-17
- Assignees: Werth Messtechnik GmbH
- Inventors: Ralf Christoph; Ingomar Schmidt; Peter Winck
- Web page: https://patentgrep.com/patent/US20140192234A1

## CPC

- H04N 5/265: Mixing
- G01B 11/03: by measuring coordinates of points
- H04N 23/673: {based on contrast or high frequency components of image signals, e.g. hill climbing method}
- H04N 23/6845: {by combination of a plurality of images sequentially taken}
- H04N 23/698: for achieving an enlarged field of view, e.g. panoramic image capture
- H04N 23/72: Combination of two or more compensation controls
- H04N 23/73: by influencing the exposure time
- H04N 23/951: by using two or more images to influence resolution, frame rate or aspect ratio
- G01B 2210/52: Combining or merging partially overlapping images to an overall image
- H04N 23/63: by using electronic viewfinders
- H04N 23/74: by influencing the scene brightness using illuminating means
- H04N 23/743: Bracketing, i.e. taking a series of images with varying exposure conditions
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

A method for generating and evaluating an image of a section of an object using an optical sensor. To generate a bright image, individual images are recorded of a section, of which individual images at least some individual images overlap at least in part in each case, and that to generate the image, the individual images or signals are aligned with respect to one another and superposed to form an overall image as the image of the at least one section, so that the evaluation of the overall image is substantially restricted to the overlapping regions of the individual images and/or the evaluation of the overall image or of a part thereof is brought about on the basis of the overlapping regions of the individual images having the latter.

## Claims

### Claim 1

Method for generating and evaluating an image of at least one section of an object with an optical sensor such as a camera,
characterized in that,
of the at least one section, individual images are recorded, of which at least several individual images in each case at least partially overlap, and in that for generating the image, the individual images or signals thereof are aligned with respect to one another and superposed to form an overall image as the image of the at least one section, wherein the evaluation of the overall image is substantially limited to the overlapping regions of the individual images and/or the evaluation of the overall image or of a portion thereof occurs on the basis of the overlapping regions of the individual images comprising said regions.

### Claim 2 (depends on 1)

Method according to claim 1,
characterized in that
individual images of several sections of the object are recorded, of which at least a few images overlap.

### Claim 3 (depends on 1)

Method according to claim 1,
characterized in that,
for generating the image, the spatial position of the individual recordings with respect to one another is taken into consideration.

### Claim 4 (depends on 1)

Method according to claim 1,
characterized in that
an integration time Ttotal is assigned to the image, in that n individual images with integration times T1, . . . , Tn are recorded, where T1, . . . , Tn in each case ≦Ttotal, in particular T1, . . . , Tn in each case <5 ms, preferably T1, . . . , Tn in each case <1 ms, particularly preferably T1, . . . , Tn in each case ≦0.5 ms, and the individual images are superposed, wherein the spatial position of the individual images with respect to one another is determined and taken into consideration in the superposition.

### Claim 5 (depends on 1)

Method according to claim 1,
characterized in that,
for the purpose of evaluating the overall image, exclusively the regions of the individual images which are contained in all the individual images are taken into consideration.

### Claim 6 (depends on 1)

Method according to claim 1,
characterized in that,
for the purpose of evaluating the overall image, all the individual images independently of any overlap are taken into consideration.

### Claim 7 (depends on 1)

Method according to claim 1,
characterized in that,
for the purpose of evaluating the overall image, at least one overlap-free region of one or more individual images is taken into consideration, and in that for the evaluation of the overlap-free region, its gray value is normalized to the gray value of the overlapping region of individual images which is to be evaluated.

### Claim 8 (depends on 1)

Method according to claim 1,
characterized in that
the gray values of regions to be evaluated are normalized, in particular they are normalized to a gray value which corresponds to a region with maximum overlap.

### Claim 9 (depends on 1)

Method according to claim 1,
characterized in that
the size of the overall image is greater than the size of an individual image.

### Claim 10 (depends on 1)

Method according to claim 1,
characterized in that
the overlapping region of the sections is less than 100%, in particular it is between 100% and 10%, preferably between 100% and 50%.

### Claim 11 (depends on 1)

Method according to claim 1,
characterized in that
the spatial position of the individual views with respect to one another is determined with the aid of the correlation of the gray values of the individual recordings and/or with the aid of the camera position determined for each individual recording, wherein the camera position is preferably determined from the axle position of a coordinate measurement apparatus, in which the camera is preferably integrated.

### Claim 12 (depends on 1)

Method according to claim 1,
characterized in that
the individual images are recorded in different positions of rotation of the object.

### Claim 13 (depends on 1)

Method according to claim 1,
characterized in that
the spatial position of the individual views with respect to one another is determined with the aid of the rotation position of the component, and the individual images are preferably rectified on the basis of the curvature of the object.

### Claim 14 (depends on 1)

Method according to claim 1,
characterized in that
the superposition occurs by the addition of the intensities or the gray values of the pixels of the individual recordings.

### Claim 15 (depends on 1)

Method according to claim 1,
characterized in that
the superposition occurs by averaging the intensities or gray values of the pixels of the individual recording, which correspond to one another in terms of position, and the resulting gray values are preferably spread, preferably by division, preferably with a factor which corresponds at most for one pixel to the number of gray values in the overall image that is utilized for the superposition.

### Claim 16 (depends on 1)

Method according to claim 1,
characterized in that,
before the superposition, the spatial position offset between the individual recordings is corrected by shifting and/or rotating, at least in the image plane of the individual recordings.

### Claim 17 (depends on 1)

Method according to claim 1,
characterized in that
the image generated from the individual recordings contains only the overlapping image sections which are present in all the individual recordings.

### Claim 18 (depends on 1)

Method according to claim 1,
characterized in that
the regions in the overall image which, after the superposition, have a gray value under the threshold value, wherein the threshold value is preferably 20%, particularly preferably 10% of the maximum gray value, remain not taken into consideration.

### Claim 19 (depends on 1)

Method according to claim 1,
characterized in that,
in the superposition, a weighting of the regions occurs, in which at least one of the individual images used for the superposition is located in the marginal region.

### Claim 20 (depends on 1)

Method according to claim 1,
characterized in that,
after the correction of the position offset between the individual recordings, the pixels of all the used individual recordings are converted into a common, preferably equidistant point grid by resampling, wherein, for each target pixel, the gray value is calculated from the gray values of the surrounding pixels, preferably by linear interpolation methods or averaging methods.

### Claim 21 (depends on 1)

Method according to claim 1,
characterized in that
the data originating from at least two individual recordings on at least in one region of the image are used together for the determination of the position of a feature in this image region, preferably by using resampling methods, which is applied to the different pixel positions of all the individual recordings.

### Claim 22 (depends on 1)

Method according to claim 1,
characterized in that
in each case several individual recordings are recorded immediately after one another, preferably each individual recording with shorter integration time T than a standard integration time of, for example, 20 milliseconds, in particular with the integration time T<5 milliseconds, preferably T<1 millisecond, particularly preferably T<0.5 millisecond.

### Claim 23 (depends on 1)

Method according to claim 1,
characterized in that
the method for determining object points and/or contours and/or dimensions of measurement objects, preferably in a coordinate measurement apparatus, is used, wherein the coordinate measurement apparatus provides means for the relative movement between a measurement object and an optical sensor.

### Claim 24 (depends on 1)

Method according to claim 1,
characterized in that,
in the case of autofocus measurements in the direction of the optical axis of the optical sensor, individual images are recorded, in that successive individual images are superposed and subdivided into groups, wherein each group forms an image for the auto focus measurement, and in that all the individual images are aligned with respect to one another taking into consideration a possibly present sideways offset with respect to the object.

### Claim 25 (depends on 1)

Method according to claim 1,
characterized in that
the superposition of the partial images occurs in such a manner that, for each partial image and each partial region of each partial image, consisting of one or more pixels, the number of the corresponding partial regions—which are to be used for the superposition—of the partial images adjacent in the movement direction, is selected separately, preferably in such a manner that the gray value of each partial region of each partial image, gray value present after the superposition, in each case preferably exceeds a common threshold value, and preferably subsequently the gray value is normalized according to the number of the superpositions.

### Claim 26 (depends on 1)

Method according to claim 1,
characterized in that,
for the superposition, equal numbers of adjacent partial images in the positive and negative movement direction are selected, and either the position of the original partial region in the movement direction, or the mean value or the median of the positions of the respective partial regions in the movement direction used for the superposition is assigned to the position of the resulting partial region in the movement direction.

### Claim 27 (depends on 1)

Method according to claim 1,
characterized in that
the method for image generation in auto focus measurements is used, preferably with an increased movement speed of >0.3 mm/s or >1 mm/s or >3 mm/s, as a standard movement speed of approximately 0.3 mm/s to 0.1 mm/s, or for the image generation for image processing measurements during a camera movement.

### Claim 28 (depends on 1)

Method according to claim 1,
characterized in that,
during the recording of the individual recordings to be superposed, a preferably flash-like illumination is switched on, wherein the individual image recording, the illumination and the recording of the position of the axes of the coordinate measurement apparatus are synchronized in such a manner that an exact position for each individual recording is present and guaranteed, so that the illumination is switched on during the integration time of each individual recording.

### Claim 29 (depends on 1)

Method according to claim 1,
characterized in that
the optical sensor is a multi-pixel optical sensor and preferably a CCD or CMOS camera.

### Claim 30 (depends on 1)

Method according to claim 1,
characterized in that,
as desired, the entire region or a partial region or several partial regions of the detection surface of the optical sensor is/are used, preferably a limited number of rows.

### Claim 31 (depends on 1)

Method according to claim 1,
characterized in that,
as measurement objects, objects are used which have a rotation symmetrical and/or cylindrical shape, in particular stents.

### Claim 32 (depends on 1)

Method according to claim 1,
characterized in that
rotation and/or swivel axles are used for the
measurement of rotation symmetrical and/or cylindrical measurement objects.

### Claim 33 (depends on 1)

Method according to claim 1, using a manual positioning device by means of which the object to be measured is adjusted relative to an optical sensor,
characterized in that,
during a positioning process and/or between several positioning processes, individual images are recorded automatically with the optical sensor, and subsequently selected individual images are assembled into an overall image and made available for further evaluation.

### Claim 34 (depends on 1)

Method according to claim 1,
characterized in that
an individual image is selected if a region of the measurement object which had previously not been completely determined is being determined by the optical sensor.

### Claim 35 (depends on 1)

Method according to claim 1,
characterized in that
the optical sensor, in particular a camera, such as a CCD or CMOS camera, records an individual image on a regular basis and/or in the case of a change in the position of the positioning device and/or if a position region of the positioning device has been reached and/or in the case of a change in illumination and/or in the case of a change of other parameters influencing the image recording and/or the image content, such as, for example, the integration time of the optical sensor or the duration or time of a flash-like illumination.

### Claim 36 (depends on 1)

Method according to claim 1,
characterized in that
the selected individual images overlap.

### Claim 37 (depends on 1)

Method according to claim 1,
characterized in that
the selected individual images are assembled using resampling methods, for example, using interpolation and averaging methods, in order to form an overall image, and are made available for further evaluation, and preferably represented on a display element, in developed form in the case of rotation symmetrical components, but preferably scaled in each case in adaptation to the size of the display unit.

### Claim 38 (depends on 1)

Method according to claim 1,
characterized in that
the detection of whether an individual image has been selected and made available for further evaluation occurs in that the position and/or the change in the position—determined by scale systems—of the movement axles to be operated manually and/or of the image content recorded by the image processing sensor is/are monitored.

### Claim 39 (depends on 1)

Method according to claim 1,
characterized in that
the monitoring comprises the determination, and in the case where an individual image has been selected, the storage of the positions and/or image contents of the respective recorded individual image, and the comparison with already available positions and/or image contents of already selected individual images.

### Claim 40 (depends on 1)

Method according to claim 1,
characterized in that,
on the basis of the comparison with already available positions and/or image contents of already selected individual images, an individual image is then selected if at least a portion of the individual image determines a region of the measurement object which has not been determined previously, wherein the measurement region of the optical sensor formed by the sensor, such as a camera measurement region, and a selected reproduction lens, is taken into consideration.

### Claim 41 (depends on 1)

Method according to claim 1,
characterized in that,
after the positioning of the work piece surface in the sharp region of the optical sensor, predominantly flat work piece regions are positioned using the lateral axles and predominately rotation symmetrical work piece regions with the additional use of a mechanical rotary axle in the measurement region of the optical sensor.

### Claim 42 (depends on 1)

Method for determining the geometry of a measurement object using an optical sensor and a manual positioning device, preferably according to claim 1,
characterized in that
the image recording occurs when there is a relative movement between the optical sensor and the measurement object, wherein the image recording by means of the optical sensor and the position recording by the means of scale systems of the manual movement axles, and preferably a flash-like illumination controlled by a trigger signal occur synchronously.

### Claim 43 (depends on 1)

Method according to claim 1,
characterized in that
the method is used in a coordinate measurement system.