Removing noise caused by artifacts from a digital image signal

Claim 3

The method of claim 1 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of pixels.

Claim 4

The method of claim 1 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of sub-pixels.

Claim 5

The method of claim 1 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of multi-pixels.

Claim 6

The method of claim 1 , wherein the imaging parameter is gray level.

Claim 7

The method of claim 5 , wherein the replacing step comprises replacing the gray levels that are outside said range with a designated gray level.

Claim 8

The method of claim 6 , further comprising the step of deriving a mean value of the gray levels in a column, and wherein said designated gray level is said mean value.

Claim 9

The method of claim 6 , wherein said designated gray level is the gray level at a boundary of said range.

Claim 10

The method of claim 8 , wherein said range setting step comprises: determining a mean value; determining a standard deviation; and setting a boundary of said range at a difference from said mean value related to said standard deviation.

Claim 11

The method of claim 1 , wherein said step of replacing imaging parameter values to obtain a revised array comprises deleting imaging parameter values that are outside of said range from said digitized image data.

Claim 12

The method of claim 1 , wherein said edge detecting step comprises identifying discontinuities in values of the imaging parameter between adjacent columns of the revised array.

Claim 13

The method of claim 1 , wherein said edge is linear and said columns are correspondingly linear.

Claim 14

The method of claim 1 , wherein the approximate position of said edge is arcuate, and said columns are correspondingly arcuate.

Claim 17

Apparatus for measuring a physical feature of an object by accurately determining a position of an edge of the feature in a digitized image of at least a portion of the object, comprising: means for locating an approximate position of the edge; means for providing digitized image data corresponding to a selected area of the object which encompasses said approximate position of the edge and having respective values of an imaging parameter for pixels within said area; means for deriving an array of m×n imaging parameter values corresponding to pixels arranged in a plurality of columns n each of which is spaced from said approximate position of the edge by a specified distance; means for setting a range of acceptable values of said imaging parameter; means for replacing all values of said imaging parameter in said array that are outside said range with a designated value to obtain a revised array of imaging parameter values; and means for accurately determining said position of the edge from said imaging parameter values in the revised array; wherein said means for setting a range of acceptable values of said imaging parameter comprises: means for deriving, for each of columns n, a distribution of the number of pixels vs. imaging parameter values; and means for setting, based on the distribution, said range of acceptable values of the imaging parameter.

Claim 18

Apparatus for measuring a physical feature of an object by accurately determining a position of an edge of the feature in a digitized image of at least a portion of the object, comprising: means for locating an approximate position of the edge; means for providing digitized image data corresponding to a selected area of the object which encompasses said approximate position of the edge and having respective values of an imaging parameter for pixels within said area; means for deriving an array of m×n imaging parameter values corresponding to pixels arranged in a plurality of columns n each of which is spaced from said approximate position of the edge by a specified distance; means for setting a range of acceptable values of said imaging parameter; means for replacing all values of said imaging parameter in said array that are outside said range with a designated value to obtain a revised array of imaging parameter values; and means for accurately determining said position of the edge from said imaging parameter values in the revised array; wherein said means for setting a range of acceptable values of said imaging parameter comprises: means for deriving, for each of columns n, a distribution of the number of pixels vs. imaging parameter values; and means for setting, based on the distribution, said range of acceptable values of the imaging parameter.

Claim 19

The apparatus of claim 15 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of pixels.

Claim 20

The apparatus of claim 15 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of sub-pixels.

Claim 21

The apparatus of claim 15 , wherein said columns n are respectively spaced from the approximate position of the edge by an integral number of multi-pixels.

Claim 22

The apparatus of claim 15 , wherein the imaging parameter is gray level.

Claim 23

The apparatus of claim 19 , wherein the means for replacing comprises means for replacing the gray levels that are outside said range with a designated gray level.

Claim 24

The apparatus of claim 20 , further comprising means for deriving a mean value of the gray levels in a column, and wherein said designated gray level is said mean value.

Claim 25

The apparatus of claim 20 , wherein said designated gray level is the gray level at a boundary of said range.

Claim 26

The apparatus of claim 15 , wherein said range setting means comprises: means for determining a mean value; means for determining a standard deviation; and means for setting a boundary of said range at a difference from said mean value related to said standard deviation.

Claim 27

The apparatus of claim 15 , wherein said means for replacing imaging parameter values to obtain a revised array comprises means for deleting imaging parameter values that are outside of said range from said digitized image data.

Claim 28

The apparatus of claim 15 , wherein said means for setting a range of acceptable values comprises means for deriving a first mean value of the imaging parameter based on all values in a column, and wherein said replacing means comprises means for deriving a second mean value based only on values within said range and replacing the values outside said range with said second mean value.

Claim 29

The apparatus of claim 15 , wherein said edge detecting means comprises means for identifying discontinuities in values of the imaging parameter between adjacent columns of the revised array.

Claim 30

The apparatus of claim 15 , wherein said edge is linear and said columns are correspondingly linear.

Claim 31

The apparatus of claim 15 , wherein the approximate position of said edge is arcuate, and said columns are correspondingly arcuate.