Image analysis – Applications – Document or print quality inspection
Reexamination Certificate
1999-04-05
2003-03-18
Mehta, Bhavesh (Department: 2721)
Image analysis
Applications
Document or print quality inspection
C382S141000, C382S149000, C250S559400
Reexamination Certificate
active
06535621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a defect integrated processing apparatus for performing an integrated processing of light and shade and/or smudgy defects and method thereof.
More particularly, the invention relates to a defect integrated processing apparatus and method for use in inspection of defects on a plain material roll (or web) based on an image data which is produced by an image pick-up camera, picking up an image of the web (e.g., paper, film and nonwoven fabric, etc.) having a certain width and traveling in one direction,
2. Description of the Related Art
Conventionally, various inspection apparatuses are well known. In a typical inspection apparatus, an image of a workpiece such as a web is picked up by using a camera and light-and-shade or minute defects of the workpiece are inspected through the use of an image signal obtained by the camera.
For example,
FIG. 16
is a block diagram showing a conventional light-and-shade inspection apparatus
160
. Apparatus
160
includes a line-sensor camera
1
for picking up an image of a web
2
as an inspected object having a constant width and traveling in one direction, an illuminator
3
for illuminating a zone R picked up by the camera
1
, and an image processing device
4
for processing data of an image picked up by the camera
1
and inspecting a defect on the web.
The line-sensor camera
1
includes, for example, a photodetector array of
1024
elements (e.g., a charge-coupled device (CCD)) disposed along a line. Specifically, the camera
1
is disposed upwardly of a central portion along a width (or transverse) direction of the web so that the photodetectors are arranged in a line array across the web in the transverse (width) direction thereof and in parallel with the transverse direction. The illuminator
3
is disposed downwardly of (e.g., beneath) the web
2
so as to illuminate the zone R to be picked up by the camera
1
from a rear surface of the web
2
.
The image processing device
4
detects a light-and-shade defect by judging whether an obtained image data such as a brightness (e.g., luminance) information is more than a predetermined value, or detects low contrast light-and-shade defects such as crevice spots and oil stains, etc., by, as a macro-filter processing, segmenting (e.g., partitioning) an image data at every predetermined range to form a plurality of segments and performing an integration within the respective segments. Thereafter, a differentiation is performed by obtaining respective differences between segments of those integration values, or, functions to detect edges and minute defects by a micro-filter processing, using a differentiating filter processing.
However, such a conventional inspection apparatus
160
is limited to a processing operation for separately or independently detecting those various defects. Thus, in the conventional inspection apparatus, a defect may be detected to be defects of more than one kind on the workpiece (e.g., a defect may be counted as a first type of defect and as a second type of defect, even though the defect constitutes a single defect). As a result, the number of defects may be incorrectly detected (e.g., to be greater than an actual number of defects).
Additionally, it is impossible to know from the detected results which features, such as an actual profile and size, etc., the respective defects as detected have on the workpiece. Further, in the detection of the low contrast light-and-shade defect by using the macro-filter processing, the presence and the absence of defects are detected at each segment (e.g., at a segment unit) defining an integrating range. Consequently, a spatial resolution becomes coarse depending on how segments on the image data are established. Thus, accurately detecting defect positions and sizes is difficult.
SUMMARY OF THE INVENTION
In view of the foregoing and other problems of the conventional systems and methods, an object of the present invention is to provide a defect integrated processing apparatus and method thereof capable of precisely detecting and obtaining a defect information including, for example, number, position and/or size of the defects, etc., by integrally processing various kinds of defects.
To overcome the above-mentioned problem and others, in a first aspect, a defect integrated processing apparatus according to the present invention for use in picking up an image of an object to be inspected to obtain an image data and then, based on the image data, inspecting defects on the object in an integrated fashion, includes:
an image pick-up device for picking up an image of an object to output an image data;
a light-and-shade defect detecting portion for detecting light-and-shade defects on the object based on the image data obtained through the image pick-up device;
a minute defect detecting portion for detecting edges and minute defects on the object by performing a differential processing of the image data obtained through the image pick-up device;
a low contrast light-and-shade defect detecting portion for performing a differential processing of an integrated image obtained through an integral processing of the image data obtained through the image pick-up device; and
a defect integrated processing portion for obtaining an integrated information involving defects by performing a processing, in an integrated fashion, of the respective defects of the light-and-shade defects obtained through the light-and-shade defect detecting portion, the minute defects obtained from the minute defect detecting portion, and the low contrast light-and-shade defects obtained through the low contrast light-and-shade defect detecting portion.
With this arrangement, various kinds of defects are processed in an integrated fashion to allow a detailed detection to obtain an accurate defect information about, for example, a number of defects, positions of defects, and/or sizes thereof, etc.
Also, according to the present invention, the light-and-defect detecting portion includes:
a projection operation portion for calculating a projection data by adding together a predetermined number of image data at a given position along a certain direction of the object, which image data are obtained through the image pick-up device;
a background operation portion for calculating a background lightness across a width direction of the object, based on the projection data obtained through the projection operation portion; and
a difference operation portion for removing variations of the background lightness across the width direction obtained through the background lightness operation portion from the image data obtained through the image pick-up device by subtracting a former background lightness from a latter image data.
With this arrangement, variations of the background lightness caused by the camera's and illuminator's optical systems and the sizes of defects, can be eliminated precisely, thereby achieving a highly reliable defect integrated processing.
Also, according to the present invention, the background lightness operation portion includes:
a filter for performing a smoothing processing of the projection data across the width direction of the object obtained through the projection operation portion; and
a normalizing portion for calculating the background lightness by dividing the smoothed data through the filter by the predetermined number used for adding together the image data at the given position.
With the projection operation portion, the number of data which are processed through smoothing can be increased substantially, thereby increasing the length of the smoothed data in comparison with the defect size. Therefore, an affect of the defects on the background lightness calculation by the smoothing processing, can be reduced, thereby performing a highly accurate background lightness calculation.
Additionally, the defect integrated processing apparatus, according to the present invention, further may include a comparing portion for comparing the output of the diffe
Choobin Barry
McGinn & Gibb PLLC
Mehta Bhavesh
Toshiba Engineering Corporation
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