A surface inspection method includes: an irradiating step of emitting oblique illumination light onto an inspection target region of steel material using two or more oblique line light sources; an imaging step of receiving each of reflected light beams of the oblique illumination light from the respective oblique line light sources, the reflected light beams being from the inspection target region, and capturing images of the inspection target region, by one or more line sensors; and a detecting step of detecting a linear surface defect at the inspection target region using the images captured at the imaging step, wherein orthographic projections of at least two oblique illumination light beams, out of the oblique illumination light from the two or more oblique line light sources, onto a surface of the steel material are orthogonal to each other on the inspection target region.

A defect inspection apparatus includes a first slit light source together with a machine base in which a through hole is formed. A second slit light source and a half mirror are provided inside the through hole. First slit light from the first slit light source is directly incident on an object to be photographed (for example, an automobile body). On the other hand, second slit light from the second slit light source proceeds in a direction perpendicular to the direction in which the first slit light proceeds, and thereafter, is refracted by the half mirror, led out from the through hole, and made incident on the object to be photographed.

Techniques are described for inspection of films in order to detect Machine Direction Line (“MDL”) defects. An example system comprises a light source configured to provide a source of light rays, directed to a film product so that the light rays are incident to a surface of the film product at a non-perpendicular angle of incidence. An image capturing device is configured to generate an image of the film product by capturing a level of light intensity of the light rays exiting the film product in a plurality of image areas, each image area representing a line imaged across the film product that is perpendicular to a direction of manufacture of the film product. An image processing device is configured to process the image of the film product to provide an indication of the detection of one or more machine direction line (MDL) defects in the film product.

The invention relates to a method for illuminating a wood fibre web for deviation detection. The method comprises turning on LEDs of an overhead sidelight that are side-directed towards a first edge of the web for illuminating a first half of width of the web, capturing an image of the first half, turning off the LEDs, turning on LEDs of the overhead sidelight that are side-directed towards a second edge of the web for illuminating a second half of width of the web, capturing an image of the second half, and turning off the LEDs. The invention also relates to an overhead sidelight, a machine vision system, and a lighting system.

Provided are a printed matter inspection device and a printed matter inspection method for appropriately determining visibility of a streaky concentration defect, regardless of the size of a variation of pixel values of an image. A printed matter inspection device determines visibility of a streak from a basic streak intensity that is an intensity of the streak detected from a printed matter, color information and frequency feature information on a streak near-field area that is continuous from an area of the streak and has a variation of image feature amounts that is within a predetermined first range, and frequency feature information on an outer peripheral area that is in contact with the streak near-field area, and determines whether the quality of the printed matter is good or not on the basis of at least the visibility.

The invention relates to a method for illuminating a wood fibre web for deviation detection. The method comprises turning on LEDs of an overhead sidelight that are side-directed towards a first edge of the web for illuminating a first half of width of the web, capturing an image of the first half, turning off the LEDs, turning on LEDs of the overhead sidelight that are side-directed towards a second edge of the web for illuminating a second half of width of the web, capturing an image of the second half, and turning off the LEDs. The invention also relates to an overhead sidelight, a machine vision system, and a lighting system.

A method for processing print data includes a matching processing step of performing pattern matching between a streak detection pattern including a streak pattern having a width of one pixel and print data after a RIP process, a length measurement step of determining, when matching is established in the matching processing step, a length of a streak candidate part including a part corresponding to the streak pattern in a region where matching is established and a part continuous in an extending direction of the streak pattern and having a same value as a data value of the streak pattern, in the print data, and a determination step of determining whether or not the streak candidate part is white streak data that possibly results in a streak, by comparing the length determined in the length measurement step against a predetermined threshold.

Provided are a printed matter inspection device and a printed matter inspection method for appropriately determining visibility of a streaky concentration defect, regardless of the size of a variation of pixel values of an image.

A printed matter inspection device determines visibility of a streak from a basic streak intensity that is an intensity of the streak detected from a printed matter, color information and frequency feature information on a streak near-field area that is continuous from an area of the streak and has a variation of image feature amounts that is within a predetermined first range, and frequency feature information on an outer peripheral area that is in contact with the streak near-field area, and determines whether the quality of the printed matter is good or not on the basis of at least the visibility.

A surface defect inspecting device for steel sheets includes: an illuminating unit configured to illuminate an imaging target portion on a surface of a steel sheet; first and second diffuse reflection light imaging units arranged at a first angle and at a second angle larger than the first angle with respect to a specular reflection direction of illuminated light reflected from the imaging target portion, respectively, imaging simultaneously reflection light of illuminated light reflected from the imaging target portion; and an image signal processor configured to process first and second diffuse reflection image signals acquired by the first and second diffuse reflection light imaging units, respectively, detecting, as a surface defect portion, a portion for which brightness level is lower than a first predetermined threshold in the first diffuse reflection image signal as well as higher than a second predetermined threshold in the second diffuse reflection image signal.

A surface defect inspecting device for steel sheets includes: an illuminating unit configured to illuminate an imaging target portion on a surface of a steel sheet; first and second diffuse reflection light imaging units arranged at a first angle and at a second angle larger than the first angle with respect to a specular reflection direction of illuminated light reflected from the imaging target portion, respectively, imaging simultaneously reflection light of illuminated light reflected from the imaging target portion; and an image signal processor configured to process first and second diffuse reflection image signals acquired by the first and second diffuse reflection light imaging units, respectively, detecting, as a surface defect portion, a portion for which brightness level is lower than a first predetermined threshold in the first diffuse reflection image signal as well as higher than a second predetermined threshold in the second diffuse reflection image signal.