Image processing apparatus and method of processing height data to obtain image data using gradient data calculated for a plurality of different points of a surface and adjusted in accordance with a selected angle of illumination
First Claim
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1. Metrological apparatus for determining the surface texture or roughness of a workpiece comprising:
- means for measuring the height of the surface at a plurality of different points on the surface to produce a corresponding plurality of height values;
processing means for;
(i) calculating gradient data at a plurality of said different points on the surface from said height values,(ii) adjusting said gradient data dependent upon a selected angle of illumination, and(iii) generating image data by combining the corresponding values of said adjusted gradient data and said height value for a plurality of said different pointswherein said processing means is arranged to combine said corresponding values of said adjusted gradient data and said input height value to generate said image data according to the relationship
space="preserve" listing-type="equation">Image.sub.-- Data(x,y)=S*Height(x,y)+T*Gradient(x,y)where Image-- Data (x,y), Height (x,y) and Gradient (x,y) are the values of said image data, said input height and said adjusted gradient data at a point (x,y) on the surface respectively and S and T are weighting coefficients; and
means for forming an image in accordance with said image data.
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Abstract
An apparatus and method for the processing of height information indicative of the roughness or texture of a surface which may be used to produce an improved two dimensional recording of the surface. The apparatus or method has particular applicability in the field on metrological instruments. In processing the surface information, the apparatus or method takes account not only of the basic height information but also of gradient information. Such gradient information is furthermore adjusted dependent upon a desired angle of illumination which may be selected by the user.
112 Citations
34 Claims
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1. Metrological apparatus for determining the surface texture or roughness of a workpiece comprising:
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means for measuring the height of the surface at a plurality of different points on the surface to produce a corresponding plurality of height values; processing means for; (i) calculating gradient data at a plurality of said different points on the surface from said height values, (ii) adjusting said gradient data dependent upon a selected angle of illumination, and (iii) generating image data by combining the corresponding values of said adjusted gradient data and said height value for a plurality of said different points wherein said processing means is arranged to combine said corresponding values of said adjusted gradient data and said input height value to generate said image data according to the relationship
space="preserve" listing-type="equation">Image.sub.-- Data(x,y)=S*Height(x,y)+T*Gradient(x,y)where Image-- Data (x,y), Height (x,y) and Gradient (x,y) are the values of said image data, said input height and said adjusted gradient data at a point (x,y) on the surface respectively and S and T are weighting coefficients; and means for forming an image in accordance with said image data. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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2. A metrological method for determining the surface texture or roughness of a workpiece comprising:
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measuring the height of the surface at a plurality of different points on the surface to produce a plurality of height values; calculating gradient data at a plurality of said different points on the surface based on said height values; adjusting said gradient data dependent upon a selected angle of illumination; generating image data by combining the corresponding values of said adjusted gradient data and said input height value for a plurality of said different points wherein said corresponding values of said adjusted gradient data and said input height value are combined to generate said image data according to the relationship
space="preserve" listing-type="equation">Image.sub.-- Data(x,y)=S*Height(x,y)+T*Gradient(x,y)where Image-- Data (x,y), Height (x,y) and Gradient (x,y) are the values of said image data, said input height and said adjusted gradient data at a point (x,y) on the surface respectively and S and T are weighting coefficients; and forming an image in accordance with said input image data. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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3. Metrological apparatus for determining the surface texture or roughness of a workpiece comprising:
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means for measuring the height of the surface at a plurality of points on the surface to produce a plurality of height values; processing means for calculating gradient data at a plurality of said height values and for adjusting said gradient data dependent upon a selected angle of illumination; and means for forming an image in accordance with the height data and the adjusted gradient data, wherein the processing means is adapted to adjust the gradient data according to the relationship;
space="preserve" listing-type="equation">Gradient(x,y)=Sinθ
*GradientX(x,y)+Cosθ
*GradientY(x,y);wherein GradientX(x,y) and GradientY(x,y) are the Gradients at point (x,y,) in the x and y directions repectively and where θ
is the selected angle.
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4. A metrological method for determining the surface texture or roughness of a workpiece comprising the steps of:
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measuring the height of the surface at a plurality of points on the surface to produce a plurality of height values; calculating gradient data at a plurality of height values; adjusting said gradient data dependent upon a selected angle of illumination; and forming an image in accordance with the height data and the adjusted gradient data wherein the gradient data is adjusted according to the relationship;
space="preserve" listing-type="equation">Gradient (x,y)=Sinθ
*GradientX(x,y)+Cosθ
*GradientY(x,y);where GradientX(x,y) and GradientY(x,y) are the gradients at point (x,y) in the x and y directions respectively and where θ
is the selected angle. - View Dependent Claims (6, 7)
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5. An image processing method for providing data for forming an image on an image carrier, said image being representative of features such as texture and roughness of a surface, the method comprising the steps of:
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inputting a plurality of height values Z(x,y) at different points on the surface; calculating gradient data at a plurality of height values; adjusting said gradient data dependent upon a selected angle of illumination; and outputting image data in accordance with the height data and the adjusted gradient data, wherein the gradient data is adjusted according to the relationship;
space="preserve" listing-type="equation">Gradient (x,y)=(Sinθ
*GradientX(x,y))+(Cosθ
*GradientY(x,y));where GradientX(x,y) and GradientY(x,y) are the gradients at point (x,y) in the x and y directions respectively and where θ
is the selected angle.
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8. Image processing apparatus for providing image data for forming an image on an image carrier, said image being representative of a characteristic of a surface, the apparatus comprising:
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input means for inputting a plurality of height values, each height value being representative of the height at a respective different point on the surface; processing means for; (i) calculating gradient data at a plurality of said different points on the surface from said input height values, (ii) adjusting said gradient data dependent upon a selected angle of illumination, and (iii) generating image data by combining the corresponding values of said adjusted gradient data and said input height value for a plurality of said different points wherein said processing means is arranged to combine said corresponding values of said adjusted gradient data and said input height value to generate said image data according to the relationship
space="preserve" listing-type="equation">Image.sub.-- Data(x,y)=S*Height(x,y)+T*Gradient(x,y)where Image-- Data (x,y), Height (x,y) and Gradient (x,y) are the values of said image data, said input height and said adjusted gradient data at a point (x,y) on the surface respectively and S and T are weighting coefficients; and output means for outputting said image data. - View Dependent Claims (9)
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20. Image processing apparatus for providing data for forming an image on an image carrier, said image being representative of features such as texture and roughness of a surface, the apparatus comprising:
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input means for inputting a plurality of height values at different points on the surface; processing means for calculating gradient data at a plurality of said height values and for adjusting said gradient data dependent upon a selected angle of illumination; and output means for outputting image data in accordance with the height data and the adjusted gradient data, wherein the processing means is adapted to adjust the gradient data according to the relationship;
space="preserve" listing-type="equation">Gradient(x,y)=(Sinθ
*GradientX(x,y)+(Cosθ
*GradientY(x,y));where GradientX(x,y) and GradientY(x,y) are the gradients at point (x,y) in the x and y directions respectively and where θ
is the selected angle. - View Dependent Claims (21, 22, 23)
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24. An image processing method for providing image data for forming an image on an image carrier, said image being representative of features such as texture and roughness of a surface, the method comprising:
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inputting a plurality of height values representative of the height at respective different points on the surface; calculating gradient data at a plurality of said different points on the surface from said input height values; adjusting said gradient data dependent upon a selected angle of illumination; generating image data by combining the corresponding values of said adjusted gradient data and said height value for a plurality of said different points wherein said corresponding values of said adjusted gradient data and said input height value are combined to generate said image data according to the relationship
space="preserve" listing-type="equation">Image.sub.-- Data(x,y)=S*Height(x,y)+T*Gradient(x,y)where Image-- Data (x,y), Height (x,y) and Gradient (x,y) are the values of said image data, said input height and said adjusted gradient data at a point (x,y) on the surface respectively and S and T are weighting coefficients; and outputting said image data. - View Dependent Claims (25)
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Specification