US 6,272,246 B1 · Positioning device

Abstract

In a positioning device, a maximum-value/minimum-value calculating section calculates the maximum value and minimum value of densities with respect to each of a target image and a reference image that has been preliminarily stored. Further, based upon the maximum values and minimum values of densities of the two images, a barrel-shifter gradation conversion section carries out bit shifts of the original images of the two images respectively so as to allow them to contain effective bits related to contrast, and gradation-converts the respective images so as to have numbers of density levels that are fewer than the original numbers of density levels thereof, thereby outputting the resulting images that have been gradation-converted. With this arrangement, even if the contrast of an original image is poor, it is possible to reduce the amount of calculations for finding the degree of similarity between the reference image and the target image without impairing the operation accuracy in finding the degree of similarity. Therefore, even if the contrast of an original image is poor, it is possible to carry out an effective rough search by using a rough search section. Moreover, since the degree of similarity is found with high precision with a minimum of the amount of calculations, the circuit scale can be minimized to the corresponding extent.

Claims18

Dependent claims

A positioning device, which carries out a positioning between a preliminarily registered reference image and a newly inputted target image, comprising:

a first calculating section for calculating features of the target image;
a first gradation conversion section which converts the gradation of the target image so as to produce a rough target image based upon the results of calculations in the first calculating section so that information related to contrast of the target image is contained to a greater extent, and so that the number of density levels of the target image is reduced;
a rough search section for finding the degree of similarity between a rough reference image whose gradation has been converted and the rough target image so as to find a maximum matching candidate point;
and
a precise search section for finding a maximum matching point between the reference image and the target image in the proximity of the maximum matching candidate point, wherein the first calculating section is a first maximum-value calculating section for calculating a maximum value of densities of the target image, and the first gradation conversion section generates the rough target image by linearly converting the density levels of the target image in a rate corresponding to the maximum value.

2 more elements

A positioning device, which carries out a positioning between a preliminarily registered reference image and a newly inputted target image, comprising:

a first calculating section for calculating features of the target image;
a first gradation conversion section which converts the gradation of the target image so as to produce a rough target image based upon the results of calculations in the first calculating section so that information related to contrast of the target image is contained to a greater extent, and so that the number of density levels of the target image is reduced;
a rough search section for finding the degree of similarity between a rough reference image whose gradation has been converted and the rough target image so as to find a maximum matching candidate point;
and
a precise search section for finding a maximum matching point between the reference image and the target image in the proximity of the maximum matching candidate point, wherein the first calculating section is a first minimum-value calculating section for calculating a minimum value of densities of the target image, and the first gradation conversion section generates the rough target image by linearly converting the density levels of the target image in a rate corresponding to the minimum value.

2 more elements

A positioning device, which carries out a positioning between a preliminarily registered reference image and a newly inputted target image, comprising:

a first calculating section for calculating features of the target image;
a first gradation conversion section which converts the gradation of the target image so as to produce a rough target image based upon the results of calculations in the first calculating section so that information related to contrast of the target image is contained to a greater extent, and so that the number of density levels of the target image is reduced;
a rough search section for finding the degree of similarity between a rough reference image whose gradation has been converted and the rough target image so as to find a maximum matching candidate point;
and
a precise search section for finding a maximum matching point between the reference image and the target image in the proximity of the maximum matching candidate point, wherein the first calculating section is a first maximum-value/minimum value calculating section for calculating a maximum value and a minimum value of densities of the target image, and the first gradation conversion section generates the rough target image by linearly converting the density levels of the target image in a rate corresponding to the maximum value and the minimum value.

2 more elements

A positioning device, which carries out a positioning between a preliminarily registered reference image and a newly inputted target image, comprising:

a first calculating section for calculating features of the target image;
a first gradation conversion section which converts the gradation of the target image so as to produce a rough target image based upon the results of calculations in the first calculating section so that information related to contrast of the target image is contained to a greater extent, and so that the number of density levels of the target image is reduced;
a rough search section for finding the degree of similarity between a rough reference image whose gradation has been converted and the rough target image so as to find a maximum matching candidate point;
and
a precise search section for finding a maximum matching point between the reference image and the target image in the proximity of the maximum matching candidate point further comprising;
a second calculating section for calculating features of the reference image, the features being the same as those calculated by the first calculating section;
and
a second gradation conversion section which converts the gradation of the reference image so as to produce the rough reference image based upon the results of calculations in the second calculating section so that information related to contrast of the reference image is contained to a greater extent, and so that the number of density levels of the reference image is reduced.

5 more elements

Dependencies are inferred from the claim text.

Positioning device

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Positioning device

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Abstract

Claims18