JP7172231B2 - Inspection device, inspection method, and program - Google Patents

Description

The present invention relates to an inspection apparatus, an inspection method, and a program.

2. Description of the Related Art An inspection device for inspecting the glossiness of an image on a printed matter is used in a system that produces printed matter by an electrophotographic method or an inkjet method.

As an inspection device for inspecting printed matter, there are a gloss illumination that irradiates light for capturing a glossy image, a density illumination that irradiates light for capturing a density image, and a gloss image and a gloss image that receive reflected light from the original. An imaging device for capturing a density image is provided, and a configuration is disclosed in which a reflective LED that generates parallel light by reflecting light emitted from the LED light emitting surface by a concave mirror is used as the lustrous illumination (Patent Document 1). ).

When capturing a glossy image, it is ideal for the imaging apparatus to receive only specularly reflected light among the light emitted from the glossy illumination (glossy illumination light) reflected by the document. However, in reality, part of the diffusely reflected light diffused on the surface of the paint (toner, ink, etc.) on the document is received by the imaging device as an error component. This error component reduces the precision of the glossy image.

In order for the imaging device to receive specularly reflected light, it is necessary that the glossy illumination light emitted from the glossy illumination has high parallelism. In a reflective LED such as the conventional technology, the larger the ratio between the size of the LED emitting surface and the size of the parabolic surface of the concave mirror, the higher the parallelism of the emitted light. be advantageous. That is, when using a reflective LED, it is required to reduce the size of the LED light emitting surface as much as possible. The size of the LED reflecting surface depends on the color of the glossy illumination light, and is larger when the glossy illumination light is white light than when it is monochromatic light (eg, blue). This is because, in order to generate white light, a process such as coating a yellow fluorescent material on a blue LED is required, which inevitably increases the size of the LED light emitting surface. Therefore, in the prior art, it is difficult to use white light as lustrous illumination light.

Here, the intensity of the diffusely reflected light fluctuates according to the hue of the paint on the original. This is because the degree of absorbance when the glossy illumination light is absorbed by the paint differs according to the hue of the paint. For example, when blue light, which is monochromatic light, is used as the lustrous illumination light, most of the diffusely reflected light is absorbed if the hue of the paint is yellow or red, so the intensity (error) of the diffusely reflected light is small. On the other hand, if the hue of the paint is blue or cyan, the diffusely reflected light is hardly absorbed, and the intensity (error) of the diffusely reflected light increases. Conventional techniques cannot adequately deal with such errors caused by diffusely reflected light that varies according to the hue of the paint.

SUMMARY An advantage of some aspects of the invention is to improve the accuracy of glossy images.

In order to solve the above-described problems and achieve the object, an inspection apparatus according to the present invention is an inspection apparatus for inspecting a gloss defect of an object, comprising an illumination device that irradiates gloss illumination light , and an RGB color space. an imaging device having a corresponding color resolution and acquiring glossy image data representing a glossy image of the object by receiving specularly reflected light of the glossy illumination light specularly reflected on the object; Based on the result of comparing the pixel value of the R image obtained by extracting the R component from the image, the pixel value of the G image obtained by extracting the G component from the glossy image, and the pixel value of the B image obtained by extracting the B component from the glossy image. and a correcting unit that corrects the glossy image data so as to reduce an error caused by the diffuse reflection of the glossy illumination light diffusely reflected on the object.

According to the present invention, it is possible to improve the accuracy of glossy images.

FIG. 1 is a diagram illustrating a configuration example of an image forming system according to an embodiment. FIG. 2 is a diagram illustrating a configuration example of a reading unit according to the embodiment; FIG. 3 is a diagram illustrating the positional relationship between glossy illumination and an imaging device according to the embodiment; FIG. 4 is a side view showing a configuration example of glossy lighting according to the embodiment. FIG. 5 is a plan view showing an example of the internal structure of glossy lighting according to the embodiment. FIG. 6 is a diagram illustrating a state in which the amount of extension of the honeycomb member according to the embodiment is relatively large. FIG. 7 is a diagram illustrating a state in which the amount of extension of the honeycomb member according to the embodiment is relatively small. FIG. 8 is a block diagram showing a hardware configuration example of the inspection apparatus according to the embodiment. FIG. 9 is a block diagram illustrating a functional configuration example of the image forming system according to the embodiment. 10A and 10B are diagrams illustrating problems in obtaining glossy image data. FIG. FIG. 11 is a diagram illustrating an example of a method for correcting glossy image data according to the embodiment. FIG. 12 is a flowchart illustrating an example of processing by the inspection device according to the embodiment;

Exemplary embodiments of an inspection apparatus, an inspection method, and a program will be described in detail below with reference to the accompanying drawings. The present invention is not limited by the following embodiments, and components in the following embodiments include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. . Various omissions, replacements, changes, and combinations of components can be made without departing from the gist of the following embodiments.

FIG. 1 is a diagram showing a configuration example of an image forming system 1 according to an embodiment. The image forming system 1 includes a printing device 100 , an inspection device 200 and a stacker 300 .

The printing apparatus 100 includes an operation panel 101, photosensitive drums 103Y, 103M, 103C, 103K, and 103CL, a transfer belt 105, a secondary transfer roller 107, a paper feeding unit 109, a transport roller pair 111, and a print engine including a fixing device 113. including.

An operation panel 101 is a user interface that receives various input operations to the printing apparatus 100 and outputs various information. Toner images are formed on the photosensitive drums 103Y, 103M, 103C, 103K, and 103CL by performing a charging process, an exposure process, and a development process in an electrophotographic system (electrophotographic process). In this embodiment, a yellow toner image is formed on the photosensitive drum 103Y, a magenta toner image is formed on the photosensitive drum 103M, a cyan toner image is formed on the photosensitive drum 103C, and a cyan toner image is formed on the photosensitive drum 103K. It is assumed that a black toner image is formed and a clear toner image is formed on the photosensitive drum 103CL, but the present invention is not limited to this. Each toner image formed on each of the photosensitive drums 103Y, 103M, 103C, 103K, and 103CL is transferred to the transfer belt 105. As shown in FIG.

The transfer belt 105 transfers toner images (full-color and glossy toner images) superimposed and transferred from the photosensitive drums 103Y, 103M, 103C, 103K, and 103CL to a secondary transfer position where a secondary transfer roller 107 is arranged. transport. In this embodiment, a yellow toner image is first transferred to the transfer belt 105, and then a magenta toner image, a cyan toner image, a black toner image, and a clear toner image are sequentially superimposed and transferred. is not limited to

A paper feed unit 109 accommodates a recording medium onto which a toner image is to be transferred, and feeds the recording medium. The recording medium may be, for example, thermal paper, plain paper, roll paper, coated paper, thick paper, OHP (Overhead Projector) sheet, plastic film, prepreg, copper foil, etc., as long as it can record an image. There may be. In this embodiment, the case where the recording medium is cut paper will be described as an example, but the present invention is not limited to this.

The conveying roller pair 111 conveys the recording medium fed by the paper feeding unit 109 in the direction of the arrow s on the conveying path a.

The secondary transfer roller 107 collectively transfers the full-color toner image conveyed by the transfer belt 105 onto the recording medium conveyed by the conveying roller pair 111 at the secondary transfer position.

The fixing device 113 heats and presses the recording medium to which the full-color toner image has been transferred, thereby fixing the full-color toner image on the recording medium.

The printing device 100 discharges a printed matter (original document), which is a recording medium on which a full-color toner image is fixed, to the inspection device 200 .

Inspection device 200 includes reader 201 and operation panel 203 .

The operation panel 203 is a user interface that receives various input operations to the inspection apparatus 200 and outputs various information. Note that the operation panel 203 may be omitted. In this case, the operation panel 101 may also serve as the operation panel 203 , or an externally connected PC (Personal Computer) may also serve as the operation panel 203 .

The reading device 201 electrically reads printed matter discharged from the printing device 100 . FIG. 2 is a diagram showing a configuration example of the reading device 201 according to the embodiment. The reading device 201 includes a gloss illumination 211 (illumination device), an imaging device 212 , a document table 213 and a linear stage 214 .

The gloss illumination 211 is an illumination device that irradiates light (gloss illumination light) for imaging a gloss image indicating the gloss distribution of the document 220, which is a printed matter to be inspected, for example, the glossiness of each pixel. Glossiness is a numerical value representing the degree of specular glossiness, and is synonymous with specular glossiness defined in JIS (Japanese Industrial Standards) Z8741 and ISO (International Organization for Standardization) 2813. That is, the gloss image indicates the light amount distribution of regular reflected light in an arbitrary viewing direction as the gloss distribution of the document 220 . The gloss illumination 211 according to this embodiment emits white light as gloss illumination light. White light is light that includes visible light wavelengths. Visible light is light with a wavelength visible to the human eye, for example, light in a wavelength range of about 380 nm to about 780 nm.

The imaging device 212 receives the reflected light of the glossy illumination light emitted from the glossy illumination 211 and reflected on the document 220, and acquires image data indicating the light amount of the received light. The imaging device 212 exemplified here is a line sensor camera including a plurality of imaging elements arranged in the Y-axis direction (the direction orthogonal to the direction in which the document 220 is conveyed), and acquires image data of the document 220 for each line. For example, a MOS (Metal Oxide Semiconductor Device), a CMOS (Complementary Metal Oxide Semiconductor Device), a CCD (Charge Coupled Device), and a CIS (Contact Image Sensor) can be used as the imaging device. The imaging device 212 according to this embodiment has a color resolution (color resolution) corresponding to full color. Full color is a color that can be expressed in the RGB color space, and although the number of colors is not particularly limited, it can be 24-bit color (true color) with 256 gradations for each of RGB colors, for example.

The document platen 213 is a member on which the document 220 is placed. A linear stage 214 is a mechanism for linearly displacing the platen 213 (along the X-axis in this example). Image data of the entire document 220 can be acquired by displacing the document 220 placed on the document platen 213 by the linear stage 214 in the direction of the arrow 221 while the imaging device 212 takes an image of the document 220 . Based on the image data acquired in this way, glossy image data representing the glossy image of the document 220 can be generated.

FIG. 3 is a diagram illustrating the positional relationship between the glossy lighting 211 and the imaging device 212 according to the embodiment. The glossy illumination 211 irradiates a glossy illumination light 225A that is incident on the reading area of the document 220, which is the object to be inspected, at a predetermined incident angle θ1. The specularly reflected light 225B is light obtained by reflecting the glossy illumination light 225A incident on the reading area of the document 220 at an incident angle θ1 in the reading area at a reflection angle θ2 (θ2=θ1) in the opposite direction to the incident direction. The glossy illumination 211 and the imaging device 212 are arranged so that θ1=θ2.

Note that, separately from the glossy lighting 211, a density lighting for irradiating light (density illumination light) for capturing a density image may be installed. A density image is an image representing the density distribution of an image on the document 220 (for example, RGB values of each pixel). In this case, the density image data representing the density image of the document 220 can be obtained by receiving the reflected light of the density illumination light from the document 220 with the imaging device 211 .

Returning to FIG. 1 , the inspection device 200 discharges the document 220 that has been read to the stacker 300 . Note that the inspection device 200 may further include a reading device that optically reads the other side of the document 220 . In this case, a reading device that optically reads the other side of the document 220 may have the same configuration as the reading device 201 .

Stacker 300 includes trays 400 . The stacker 300 stacks the originals 220 ejected by the inspection device 200 on the tray 400 .

FIG. 4 is a side view showing a configuration example of the gloss illumination 211 according to the embodiment. FIG. 5 is a plan view showing an example internal structure of the glossy lighting 211 according to the embodiment. FIG. 5 mainly shows the members related to the irradiation of the glossy illumination light among the internal structure of the glossy illumination 211 .

The glossy illumination 211 according to this embodiment includes bases 301A and 301B, spacers 302, power supply substrates 303, connectors 304, base plates 305, shims 306A and 306B, radiators 307, flexible substrates 308, LEDA (Light Emitting Diode Array) 309, It includes a rod lens 310, lens supports 311A and 311B, a honeycomb member 312, a diffuse transmission film 313, specular reflection films 314A and 314B, a dustproof film 315, and light shielding films 316A and 316B.

The bases 301A and 301B are members constituting the housing of the glossy lighting 211. The base 301A constitutes the upper side of the housing, and the base 301B constitutes the lower side of the housing. In the space formed by the bases 301A and 301B, other constituent elements forming the gloss lighting 211 are arranged.

A spacer 302 is interposed between the bases 301A and 301B to secure a space between the bases 301A and 301B.

The power board 303 is a power source for the glossy lighting 211 and supplies power to the flexible board 308 on which the LEDA 309 is installed via the connector 304 .

The connector 304 electrically connects the power board 303 and the flexible board 308 .

A base plate 305 is a plate for supporting the flexible substrate 308 . Base plate 305 is fixed to base 301A using upper shim 306A and fixed to base 301B using lower shim 306B.

Shim 306A is a wedge for fixing base plate 305 to base 301A. Shim 306B is a wedge for fixing base plate 305 to base 301B.

The radiator 307 is a member that dissipates the heat generated by the LEDA 309, and the LEDA 309 (
It is installed on the surface opposite to the surface of the base plate 305 on which the flexible substrate 308) is installed.

A flexible substrate 308 is a deformable substrate for supporting the LEDA 309 and supported by the base plate 305 .

The LEDA 309 is a light source in which a plurality of LED chips (an example of light emitting elements) are arranged. The LEDA 309 emits light based on the supply of power from the power supply board 303 to emit illumination light (more specifically, diffuse illumination light). In this embodiment, since the LEDA 309 is supported by the flexible substrate 308, the LEDA 309 can be arranged in a shape that allows the flexible substrate 308 to deform. As a result, as shown in FIG. 5, the LEDA 309 can have a structure in which a plurality of LED chips are curved and arranged. In addition, in the LEDA 309 illustrated in FIG. 5, a plurality of LED chips are arranged side by side in a curved surface having a first curvature.

The rod lens 310 corrects the optical path so as to guide the illumination light emitted from the LEDA 309 into the honeycomb member 312 as much as possible. The rod lens 310 particularly corrects the optical path of the illumination light emitted from the LEDA 309 in the vertical direction (Z-axis direction). Here, the correction of the optical path of the illumination light emitted from the LEDA 309 is exemplified by a rod lens method using a rod lens 310. However, it is not limited to this, and a reflector method, a cylindrical lens method, or the like may be used. .

Lens supports 311A and 311B are members for fixing rod lens 310 at a predetermined position.

The diffuse transmission film 313 is adhered to the surface of the honeycomb member 312 on the rod lens 310 side (the surface on which the illumination light emitted from the LEDA 309 is incident), and diffuses and transmits the illumination light emitted from the LEDA 309. , into the honeycomb member 312 .

The specular reflection film 314A is adhered to the top of the surface of the diffusion transmission film 313 on the rod lens 310 side (the surface on which the illumination light emitted from the LEDA 309 is incident). The specular reflection film 314B is adhered to the lower part of the surface of the diffuse transmission film 313 on the rod lens 310 side (the surface on which the illumination light emitted from the LEDA 309 is incident).

The specular reflection films 314A and 314B reflect the illumination light whose optical path has not been corrected to be guided into the honeycomb member 312 by the rod lens 310 . As a result, the optical path of the reflected illumination light is corrected by the rod lens 310 so as to be guided into the honeycomb member 312 again. As a result, effective use of illumination light can be expected.

The honeycomb member 312 is a member having an expandable honeycomb structure. The honeycomb member 312 is arranged in a curved surface having a second curvature larger than the first curvature in the irradiation direction of the illumination light from the LEDA 309 . The LEDA 309 and the honeycomb member 312 have the same center of curvature and are curved in the longitudinal direction of the honeycomb member 312 (the direction in which the plurality of LED chips are arranged). The honeycomb member 312 may be made of any material, such as aluminum or paper. In this embodiment, the degree of parallelism of the glossy illumination light 225A to the X-axis direction in the XZ plane can be adjusted by adjusting the degree of expansion and contraction of the honeycomb structure of the honeycomb member 312 (the shape of the honeycomb structure). That is, the honeycomb members 312 play a role as louvers. The principle by which the honeycomb member 312 can adjust the degree of parallelism of the lustrous illumination light 225A will be described later.

The dust-proof film 315 is a film for preventing dust or the like from entering the glossy illumination 211 .

The light shielding films 316A and 316B shield at least part of the illumination light transmitted through the honeycomb member 312 along the longitudinal direction of the honeycomb member 312 . The light-shielding film 316A is adhered to the upper part of the surface of the dust-proof film 315 on the honeycomb member 312 side (the surface on which the illumination light transmitted from the honeycomb member 312 is incident). Illumination light transmitted in the upper direction (Z-axis direction) is blocked along the longitudinal direction (Y-axis direction) of the honeycomb member 312 . The light-shielding film 316B is adhered to the lower portion of the surface of the dust-proof film 315 on the honeycomb member 312 side (the surface on which the illumination light transmitted from the honeycomb member 312 is incident), and extends in the lateral direction (Z-axis direction) of the honeycomb member 312. ) is blocked along the longitudinal direction of the honeycomb member 312 .

In this embodiment, the degree of parallelism of the glossy illumination light 225A can be adjusted by adjusting the distance between the light shielding films 316A and 316B (the degree of opening of the dustproof film 315).

The illumination light that has passed through the honeycomb member 312 and has passed through the dustproof film 315 without being blocked by the light shielding films 316A and 316B is irradiated onto the reading area on the document 220 as glossy illumination light 225A.

Here, the principle by which the honeycomb member 312 can adjust the degree of parallelism of the glossy illumination light 225A will be described. FIG. 6 is a diagram illustrating a state in which the amount of extension of the honeycomb member 312 according to the embodiment is relatively large. FIG. 7 is a diagram illustrating a state in which the amount of extension of the honeycomb member 312 according to the embodiment is relatively small.

As shown in FIG. 6, when the honeycomb member 312 is extended relatively large in the Y-axis direction, which is the longitudinal direction, the degree of opening of each honeycomb in the Y-axis direction becomes large, so that illumination with a high degree of parallelism with respect to the X-axis direction can be obtained. The honeycomb member 312 outputs not only light but also illumination light having a relatively low degree of parallelism with respect to the X-axis direction.

On the other hand, as shown in FIG. 7, when the honeycomb member 312 is contracted in the Y-axis direction, which is the longitudinal direction, the degree of opening of each honeycomb in the Y-axis direction becomes smaller, so that only illumination light that is highly parallel to the X-axis direction can be projected. is output from the honeycomb member 312, and illumination light with a relatively low degree of parallelism is not output.

As described above, in the present embodiment, the illumination light output from the honeycomb member 312 can be limited to light with a high degree of parallelism as the degree of opening of each honeycomb is reduced. In addition, the illumination light output from the honeycomb member 312 can include light with a slightly reduced degree of parallelism as the degree of opening of each honeycomb increases. That is, by adjusting the degree of opening of each honeycomb, the degree of parallelism of the glossy illumination light 225A can be arbitrarily adjusted.

Next, the hardware configuration of the inspection device 200 will be described. FIG. 8 is a block diagram showing a hardware configuration example of the inspection device 200 according to the embodiment. The inspection apparatus 200 exemplified here has a configuration in which a controller 401 and an engine section (Engine) 402 are connected by a PCI bus. The controller 401 is an electronic control unit that controls the overall control of the inspection apparatus 200 , drawing, communication, and input from the operation display section 403 . The engine unit 402 is an engine that can be connected to the PCI bus, such as a scanner engine such as a scanner. The engine unit 402 may include an image processing part such as error diffusion and gamma conversion in addition to the engine part.

Controller 401 has CPU 411 , North Bridge (NB) 412 , System Memory (MEM-P) 413 , South Bridge (SB) 414 , Local Memory (MEM-C) 415 , ASIC 416 and Hard Disk Drive (HDD) 417 . Northbridge (NB) 412 and ASIC 416 are connected by AGP bus 418 . MEM-P 413 includes ROM 414A and RAM 414B.

The CPU 411 performs overall control of the inspection apparatus 200, and is connected to other devices via a chipset consisting of the NB412, MEM-P413, and SB414.

NB 412 is a bridge for connecting CPU 411 , MEM-P 413 , SB 414 and AGP bus 418 . The NB412 includes a memory controller, PCI master, and AGP target that control reading and writing to and from the MEM-P413.

The MEM-P 413 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a drawing memory for printers, and the like. The ROM 413A is a read-only memory used as a memory for storing programs and data. The RAM 413B is a writable and readable memory used as a memory for developing programs and data, a drawing memory for a printer, and the like.

The SB 414 is a bridge for connecting the NB 412 and PCI devices (peripheral devices). SB 414 is connected to NB 412 via a PCI bus. A network interface unit and the like are also connected to this PCI bus.

ASIC 416 is an IC for image processing applications that has hardware elements for image processing. ASIC 416 serves as a bridge connecting AGP bus 418 , PCI bus, HDD 417 and MEM-C 415 . The ASIC 416 includes a PCI target, an AGP master, an arbiter (ARB) that forms the core, a memory controller that controls the MEM-C 917, multiple DMACs that rotate image data by hardware logic, etc., and a PCI interface with the engine unit 402. It includes a PCI unit and the like for data transfer via a bus. A USB 419 and an IEEE1394 interface 420 are connected to the ASIC 416 via a PCI bus. The operation display section 403 is directly connected to the ASIC 416 .

MEM-C 415 is a local memory used as an image buffer for copying, an encoding buffer, and the like. The HDD 417 is storage for accumulating image data, programs, font data, forms, and the like.

AGP bus 418 is a bus interface for graphics accelerator cards proposed to speed up graphics processing. High-throughput direct access to the MEM-P 413 via the AGP bus 418 allows for faster graphics accelerator cards.

FIG. 9 is a block diagram showing a functional configuration example of the image forming system 1 according to the embodiment. The printing apparatus 100 includes a RIP (Raster Image Processor) unit 501 , a print control unit 502 and a printing unit 503 . The inspection device 200 includes a reading unit 601 , a glossy image correction unit 602 and an inspection unit 603 .

Although the case where the printing apparatus 100 has the RIP unit 501 is exemplified here, the RIP unit 501 may be provided in a device different from the printing apparatus 100, such as a DFE (Digital Front End).

Further, here, it is assumed that the printing device 100 and the inspection device 200 are connected by a local interface such as USB (Universal Serial Bus) or PCIe (Peripheral Component Interconnect Express). The connection form with is not limited to this.

The RIP unit 501 and print control unit 502 can be implemented by cooperation of, for example, a CPU and programs stored in a predetermined non-volatile memory. The printing unit 503 is realized by, for example, the photosensitive drums 103Y, 103M, 103C, 103K, 103CL, the transfer belt 105, the secondary transfer roller 107, the fixing device 113, etc., but is not limited to this. This embodiment exemplifies a configuration in which an image is printed by an electrophotographic method, but the present invention is not limited to this, and an image may be printed by an inkjet method.

The reading unit 601 can be realized by the reading device 201, the engine unit 402, and the like. The gloss image correcting unit 602 can be implemented by, for example, cooperation of the CPU 411, system memory 413, programs stored in the ROM 413A, and the like.

A RIP unit 501 receives print data from an external device such as a host device, performs RIP processing on the received print data, and generates RIP image data (raster data, etc.). In this embodiment, it is assumed that print data includes job information described in a page description language (PDL) such as PostScript (registered trademark), image data in TIFF (Tagged Image File Format) format, and the like. However, it is not limited to this. Also, in the present embodiment, it is assumed that the RIP unit 501 generates CMYK RIP image data, but the present invention is not limited to this.

The print control unit 502 transmits the RIP image data generated by the RIP unit 501 to the printing unit 503 .

A printing unit 503 executes a print processing process such as an electrophotographic method, prints a print image based on RIP image data on a recording medium, and generates a printed matter (document 220).

A reading unit 601 reads a document 220 which is a printed material to be inspected and printed by the printing unit 503 . Specifically, the glossy illumination light 211 irradiates the document 220 placed on the document platen 213 with glossy illumination light (white light) 225A, and the imaging device 212 receives the specularly reflected light 225B. Obtain glossy image data representing a glossy image.

A glossy image correction unit 602 corrects the glossy image data acquired by the reading unit 601 based on the result of comparing the pixel values of the R, G, and B images of the glossy image. The R image is an image obtained by extracting the R component from the glossy image, the G image is an image obtained by extracting the G component from the glossy image, and the B image is an image obtained by extracting the B component from the glossy image. . A glossy image correction unit 602 corrects the glossy image data so that an error due to diffusely reflected light, which will be described later, is reduced.

An inspection unit 603 inspects the document 220 based on the glossy image data corrected by the glossy image correction unit 602 .

Here, the necessity of correcting glossy image data will be described. 10A and 10B are diagrams illustrating problems in obtaining glossy image data. FIG. When capturing a glossy image (obtaining glossy image data), it is ideal for the imaging device 212 to receive only specularly reflected light 225B obtained by specularly reflecting the glossy illumination light 225A on the document 220 . However, the light actually received by the imaging device 212 includes part of the diffusely reflected light 226 in addition to the specularly reflected light 225B. The diffusely reflected light 226 is, for example, light emitted from the surface of the paint 270 such that the glossy illumination light 225A is transmitted through the paint (toner, ink, etc.) 270, reflected by the surface of the document 220, and diffused from the surface of the paint 270. Part of the diffusely reflected light 226 becomes diffusely reflected light 226A having the same or substantially the same traveling direction as the specularly reflected light 225B. The diffusely reflected light 226A is received by the imaging device 212 together with the specularly reflected light 225B, and causes a reduction in the accuracy of the glossy image.

If the intensity of the diffusely reflected light 226A is always constant, the glossy image data can be easily corrected, but the intensity of the diffusely reflected light 226A changes according to the hue of the paint 270 and the like. For example, when the glossy illumination light 226A is blue light (monochromatic light) and the paint 270 is yellow or red, almost all of the glossy illumination light 226A is absorbed by the toner 270, so the intensity of the diffusely reflected light 226A is weaker and the error is smaller. On the other hand, when the glossy illumination light 226A is blue and the paint 270 is blue or cyan, the glossy illumination light 226A is hardly absorbed, so the intensity of the diffusely reflected light 226A increases and the error increases.

As described above, the influence of the diffusely reflected light 226A varies depending on the hue of the paint 270 and the like. The influence of light 226A cannot be sufficiently suppressed. Therefore, in the present embodiment, the glossy illumination light 211 that irradiates white light as the glossy illumination light 225A and the imaging device 212 that has a color resolution corresponding to full color are used, and R image, G image, and B image of the glossy image are used. based on the comparison result of each pixel value, the glossy image data is corrected so that the error due to the diffusely reflected light 226A is reduced. This makes it possible to improve the accuracy of the glossy image.

FIG. 11 is a diagram illustrating an example of a method for correcting glossy image data according to the embodiment. FIG. 11 exemplifies a document image 281 for which a glossy image is captured. The document image 281 exemplified here includes nine image areas 282A to 282I, and the hue and glossiness of each image area 282A to 282I are different from each other.

Also, in FIG. 11, an R image 285, a G image 286, a B image 287, and a glossy image 291 are illustrated. The R image 285 is an image obtained by extracting pixel values of the R component from a glossy image (glossy image before correction) obtained by imaging the document image 281 with the imaging device 212 . The G image 286 is an image obtained by extracting the pixel values of the G component from the glossy image before correction. The B image 287 is an image obtained by extracting the pixel values of the B component from the glossy image before correction. The pixel value here indicates glossiness, and in this embodiment, the larger the pixel value, the higher the glossiness, and the smaller the pixel value, the lower the glossiness.

Each of the R image 285, G image 286, and B image 287 includes a plurality of image areas corresponding to the respective image areas 282A to 282I of the original image 281. FIG. Here, the image areas 295 to 297 corresponding to the image area 282I will be focused on and explained. As image areas corresponding to the image area 282I of the document image 281, the R image 285 includes an image area 295, the G image includes an image area 296, and the B image includes an image area 297. FIG.

In the example shown in FIG. 11, the pixel value Kr in the image area 295 of the R image 285, the pixel value Kg in the image area 296 of the G image 286, and the pixel value Kb in the image area 297 of the B image 287 correspond to each other. is a pixel value of a pixel at a position where Kb<Kg<Kr. That is, the glossiness of the image area 297 of the B image 287 is lower than the glossiness of the image area 297 of the B image 287 and the glossiness of the image area 295 of the R image 285 . In such a case, the pixel value Kb of the B image 287, which is the smallest value (indicating the lowest glossiness), is adopted as the pixel value K of the final (corrected) glossy image 291. FIG.

The reason why the pixel values Kr, Kg, and Kb differ as described above is that the intensity of the diffusely reflected light 226A received by the imaging device 212 varies according to the hue of the paint 270. FIG. The smallest pixel value Kb indicates that the influence of the diffusely reflected light 226A is the smallest. Therefore, by adopting the smallest pixel value Kb as the final pixel value, it is possible to minimize the influence of the diffusely reflected light 226A that changes according to the hue of the paint 270. FIG.

In order to prevent the gain difference between the R image 285, the G image 286, and the B image 287, a document having a black gloss difference is used, and the R image 285, the G image 286, and the B image 287 are all the same. It is preferable to set the gain value in advance so as to have the pixel value. Also, if the glossy image data representing the glossy image 291 is at a so-called image signal level (eg, 8 bits), processing for converting this into glossiness is required.

FIG. 12 is a flow chart showing an example of processing by the inspection device 200 according to the embodiment. The inspection unit 603 cuts out an image corresponding to reading for a specified time from the glossy image data acquired by the glossy image acquiring unit 602, and performs shading processing (step S).
101). For example, the inspection unit 603 calculates the average value of the pixel values for each pixel row in the width direction of the document 220 for the cut image, and adjusts each pixel value so that the average value is a predetermined value for all the pixel rows. Calculate the coefficients of the pixel column. Then, the inspection unit 603 multiplies the pixel values of the pixels forming each pixel row by the coefficient, thereby performing shading processing on the cropped image. Since the thermal paper, which is the base of the document 220, is basically white, it can be assumed that it has a constant reflectance over its entire area. Therefore, by performing the shading process as described above, the illumination intensity unevenness can be corrected.

Subsequently, the inspection unit 603 performs binarization processing for binarizing the shading-processed image with a designated threshold value (step S103). Since defective portions of thermal paper occur on the black side (low-glossy portions), it is assumed here that portions having a specified image signal value or less are binarized and extracted.

Subsequently, the inspection unit 603 performs labeling processing on the binarized image (step S105). Specifically, the inspection unit 603 performs numbering and feature extraction for each part extracted by the binarization process. The feature amount includes at least one of the area, perimeter, aspect ratio, etc. of the part extracted by the binarization process, but is not limited to these.

Subsequently, the inspection unit 603 performs defect determination processing for inspecting gloss defects in the document 220 by comparing the feature amount of each portion subjected to the labeling process and the threshold value for gloss inspection (step S107).

The inspection unit 603 associates the inspection result indicating the position, type, etc. of the gloss defect with the gloss image data, stores the same in the HDD 417 , or transmits (feeds back) the result to the printing apparatus 100 .

A program that realizes the functions of the inspection apparatus 200 according to the above embodiment is a file in an installable format or an executable format, and can be stored on a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), or the like. It may be configured to be recorded on a computer-readable recording medium and provided. Alternatively, the program may be stored on another computer connected to a network such as the Internet, and provided by being downloaded via the network. Also, the program may be configured to be provided or distributed via a network.

As described above, according to the present embodiment, it is possible to suppress the error caused by the diffusely reflected light 226A that fluctuates according to the hue of the paint 270 and improve the accuracy of the gloss image data.

Although the embodiment of the present invention has been described above, the above embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and its equivalents.

1 Image Forming System 100 Printing Device 101 Operation Panel 103Y, 103M, 103C, 103K, 103CL Photosensitive Drum 105 Transfer Belt 107 Secondary Transfer Roller 109 Paper Feed Section 111 Conveying Roller Pair 200 Inspection Device 201 Reading Device 203 Operation Panel 211 Glossy Illumination 212 Imaging device 213 Document table 214 Linear stage 220 Document 225A Glossy illumination light 225B Regular reflection light 226, 226A Diffuse reflection light 270 Paint 281 Document image 282A to 282I, 295 to 298 Image area 285 R image 286 G image 287 B image 291 Gloss Image 300 Stacker 301A, 301B Base 302 Spacer 303 Power board 304 Connector 305 Base plate 306A, 306B Shim 307 Radiator 308 Flexible board 309 LEDA
310 rod lens 311A, 311B lens support 312 honeycomb member 313 diffuse transmission film 314A, 314B specular reflection film 315 dustproof film 316A, 316B light shielding film 400 tray 401 controller 402 engine section 403 operation display section 411 CPU
412 NB
413 MEM-P
413A ROM
413B RAM
414 SB
415 MEM-C
416 ASICs
417 HDDs
419 USB
420 IEEE1394 Interface 501 RIP 502 Print Control Unit 503 Print Unit 601 Reading Unit 602 Glossy Image Correction Unit 603 Inspection Unit

JP 2014-53106 A

Claims (5)

An inspection device for inspecting a gloss defect of an object,
a lighting device that emits lustrous illumination light ;
An imaging device having a color resolution corresponding to an RGB color space and acquiring glossy image data representing a glossy image of the object by receiving specularly reflected light of the glossy illumination light that is specularly reflected on the object. When,
A result of comparing the pixel value of the R image obtained by extracting the R component from the glossy image, the pixel value of the G image obtained by extracting the G component from the glossy image, and the pixel value of the B image obtained by extracting the B component from the glossy image. a correction unit that corrects the glossy image data so that an error due to diffusely reflected light diffusely reflected on the object is reduced based on the above;
inspection device. The correction unit adopts, as the pixel value of the glossy image, a pixel value indicating the lowest glossiness among the pixel values of the R image, the pixel value of the G image, and the pixel values of the B image, which correspond to each other. ,
The inspection device according to claim 1. The illumination device includes a honeycomb member that changes the parallelism of the glossy illumination light ,
The inspection device according to claim 1 or 2. An inspection method for inspecting a gloss defect of an object,
obtaining glossy image data representing a glossy image of the object by causing an imaging device having a color resolution corresponding to the RGB color space to receive the specularly reflected light of the glossy illumination light specularly reflected on the object; When,
A result of comparing the pixel value of the R image obtained by extracting the R component from the glossy image, the pixel value of the G image obtained by extracting the G component from the glossy image, and the pixel value of the B image obtained by extracting the B component from the glossy image. a step of correcting the glossy image data so that an error due to diffuse reflection of the glossy illumination light diffusely reflected on the object is reduced based on;
inspection methods including; In the computer that controls the inspection device that inspects the gloss defect of the object ,
A process of acquiring glossy image data representing a glossy image of the object by causing an imaging device having a color resolution corresponding to the RGB color space to receive the specularly reflected light of the glossy illumination light specularly reflected on the object. When,
A result of comparing the pixel value of the R image obtained by extracting the R component from the glossy image, the pixel value of the G image obtained by extracting the G component from the glossy image, and the pixel value of the B image obtained by extracting the B component from the glossy image. a process of correcting the glossy image data so as to reduce an error due to diffusely reflected light diffusely reflected on the object based on the glossy illumination light ;
program to run.

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