Method for evaluating contamination on surface of object and imaging box used for the method

A method for evaluating the contamination of a surface of an object comprising the steps of:

• taking an image of the surface of the object;
• dividing the image obtained by the step of taking an image into a dot matrix to obtain lightness per dot;
• selecting an area to be evaluated on the dot matrix;
• calculating a standard deviation of lightness from the distribution of lightness of the selected area as a contamination index;
• and
• evaluating the contamination based on the contamination index.

A method for evaluating the contamination of a surface of an object comprising the steps of:

• taking a color image of the surface of the object;
• converting a color image data denoting the color image obtained by the step of taking an color image into a monochromatic image data;
• dividing a monochromatic image denoted by the monochromatic image data into a dot matrix to obtain lightness per dot;
• selecting an area to be evaluated on the dot matrix;
• calculating a standard deviation of lightness from the distribution of lightness of the selected area as a contamination index;
• and
• evaluating the contamination based on the contamination index.

A method for evaluating the contamination of a surface of an object comprising the steps of:

• taking an image of the surface of the object;
• dividing the image obtained by the step of taking an image into a dot matrix to obtain lightness per dot;
• selecting an area to be evaluated on the dot matrix;
• calculating a standard deviation of lightness from the distribution of lightness of the selected area as a first contamination index;
• calculating a standard deviation of maximal value of lightness from the distribution of maximal value of lightness of the selected area as a second contamination index, when the first contamination index is larger than a predetermined value;
• and
• evaluating the contamination based on the second contamination index.

A method for evaluating the contamination of a surface of an object comprising the steps of:

• taking a color image of the surface of the object;
• converting a color image data denoting the color image obtained by the step of taking an color image into a monochromatic image data;
• dividing a monochromatic image denoted by the monochromatic image data into a dot matrix to obtain lightness per dot;
• selecting an area to be evaluated on the dot matrix;
• calculating a standard deviation of lightness from the distribution of lightness of the selected area as a first contamination index;
• calculating a standard deviation of maximal value of lightness from the distribution of maximal value of lightness of the selected area as a second contamination index, when the first contamination index is larger than a predetermined value;
• and
• evaluating the contamination based on the second contamination index.

An imaging box used for a method of evaluating the contamination on a surface of an object based on lightness distribution of an image of the surface of the object taken by a camera comprising:

• a first box-shaped envelope having an opening in which a lens portion of the camera is fitted with being faced inward, an inner surface of the first envelope having a low reflectivity structure;
• a second box-shaped envelope in which an object is positioned in front of the lens portion, the second envelope including a light source inside or outside thereof for illuminating the object from a direction oblique thereto and an inner surface of the second envelope having a low reflectivity structure;
• and
• a light-shielding member, provided in the first envelope and/or the second envelope, for preventing direct and reflected light from the light source from impinging upon the lens portion of the camera, an inner surface of the light-shielding member having a low reflectivity structure;
• wherein the first and second envelopes construct together one space.

An imaging box used for a method of evaluating the contamination on a surface of an object based on lightness distribution of an image of the surface of the object taken by a camera comprising:

• a first box-shaped envelope having an opening in which a lens portion of the camera is fitted with being faced inward, an inner surface of the first envelope having a low reflectivity structure;
• a second box-shaped envelope having a window opposed to the object in front of the lens portion, the second envelope including a light source inside or outside thereof for illuminating the object from a direction oblique thereto and an inner surface of the second envelope having a low reflectivity structure;
• and
• a light-shielding member, provided in-the first envelope and the second envelope, for preventing direct and reflected light from the light source from impinging upon the lens portion of the camera, an inner surface of the light-shielding member having a low reflectivity structure;
• wherein the first and second envelopes construct together one space.