JP7176382B2 - Image processing device - Google Patents

Description

The present invention relates to an image processing device.

2. Description of the Related Art Conventionally, in an image forming apparatus, there is known a technique of forming a base image on a recording medium and then forming an upper layer image on the base image. Since the background color of the recording medium used for packages and the like is often not white, for example, when an image is printed on the recording medium using the four colors of YMCK, there are many cases where the target color in the image cannot be reproduced.

For example, if the recording medium is a transparent sheet, the YMCK color images are fixed on the recording medium and then allow light to pass therethrough, making it impossible to reproduce the desired colors in the image. Therefore, in the technique described above, for example, a white base image is formed on a recording medium, and then an upper layer image of another color is formed on the base image, thereby reproducing a target color in the upper layer image. enable In addition, when a silver metallic toner is used for the base image, it is possible to reproduce a metallic texture having gold or other colors.

In the base image, there are cases where a sufficient adhesion amount cannot be obtained or fixing cannot be achieved in a single image forming process. The technology that is formed becomes effective. With such a technique, when a base image and an upper layer image are superimposed on a recording medium, the transfer position of the base image and the transfer position of the upper layer image may shift.

In order to make such positional deviation between the upper layer image and the base image (hereinafter referred to as "positional deviation") inconspicuous, for example, Japanese Patent Laid-Open No. 2002-200002 detects an area where the base image protrudes from the upper layer image. A technique for setting the pixel value of the background image in the detected area to 0 is disclosed. This suppresses the background image from protruding from the upper layer image.

JP 2015-222323 A

However, even if the above countermeasures are taken, misalignment may still occur between the upper layer image and the base image. For example, the size of the background image formed on the recording medium may expand or contract with respect to the design value. This is due to heat in an image forming apparatus using heat fixing, and due to moisture in ink in an image forming apparatus using ink.

Depending on the expansion/contraction state of such a background image, the positional deviation described above is likely to occur. If the positional deviation occurs, there is a possibility that the base image may protrude from the upper layer image, or an image defect may occur in which a portion of the upper layer image has no base image. In particular, when a base image is formed on a low-brightness recording medium with a white toner or a metallic toner, a portion where the base image protrudes from the upper layer image is likely to be conspicuous and easily recognized as an image defect.

In the configuration described in Japanese Patent Application Laid-Open No. 2002-200013, since expansion and contraction of the background image as described above is not taken into consideration, there is a limit to the configuration for suppressing positional deviation.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image processing apparatus capable of reducing the occurrence of image defects caused by misalignment between an upper layer image and a base image.

An image processing apparatus according to the present invention includes:
a processing unit that performs image processing when forming an upper layer image and a base image, which is the base of the upper layer image, on the same recording medium by forming images a plurality of times;
a specifying unit that specifies the base image based on the input image data;
with
The processing unit adds a border image having the same color as the background portion of the upper layer image to a portion of the upper layer image that matches the contour portion of the base image specified by the specifying unit. stomach,
When the recording medium is transparent, the color of the background portion is a color according to the mode of use of the recording medium after the image is formed .

According to the present invention, it is possible to reduce the occurrence of image defects caused by misalignment between the upper layer image and the base image.

1 is a diagram schematically showing the overall configuration of an image forming apparatus to which an image processing section according to an embodiment of the invention is applied; FIG. 3 is a diagram showing main parts of a control system of the image forming apparatus; FIG. FIG. 3 is a diagram showing a state in which an image is formed on a recording medium with a colored background portion; It is a figure which shows 1st white image data. FIG. 4 is a diagram showing Y color image data; FIG. 4 is a diagram showing M-color image data; FIG. 4 is a diagram showing C-color image data; FIG. 4 is a diagram showing K-color image data; It is a figure which shows the 2nd white image data. FIG. 10 is a diagram showing input image data composed of each data shown in FIGS. 4 to 9; FIG. 3 is a block diagram showing an image processing unit according to the embodiment; FIG. It is a figure which shows an example of an upper layer image. FIG. 4 is a diagram showing an upper layer image formed on a recording medium without an underlying image; FIG. 10 is a diagram showing an example of positional deviation between an upper layer image and a base image; FIG. 13 shows an upper layer image and an edge image; FIG. 4 is a diagram showing an upper layer image and a border image formed on a recording medium; FIG. 5 is a diagram showing an example of color options displayed on the display unit; 4 is a flowchart showing an example of image processing control operation in an image processing unit; FIG. 10 is a diagram showing an upper layer image and a border image formed on a recording medium in a state where the size of the base image is changed; FIG. 10 is a diagram showing an upper layer image and a border image formed on a recording medium without changing the size of the base image; FIG. 11 shows an upper layer image, a first edge image and a second edge image; FIG. 11 shows a first edge image and a second edge image at an arbitrary position; FIG. 21 is a diagram showing tone distributions of a first edge image and a second edge image with respect to lateral positions in FIG. 20; Figure 21 shows the image of Figure 20 after smoothing; FIG. 22 is a diagram showing the state when the gradation distributions of the first edge image and the second edge image with respect to the positions in FIG. 21 are moved inside and outside the boundary; FIG. 22 is a diagram showing the state of the gradation distribution of the first edge image and the second edge image with respect to the position in FIG. 21 after adjusting a predetermined range; FIG. 10 is a diagram showing an upper layer image and a border image formed on a recording medium when the color of the border image is set to a color based on detection information; FIG. 4 is a diagram showing an upper layer image and a border image formed on a recording medium when the base image is a silver toner; It is a figure which shows the example in which another image exists in predetermined width. It is a figure which shows the example in which another image exists in predetermined width. It is a figure which shows 1st white image data. FIG. 4 is a diagram showing first silver image data; FIG. 10 is a diagram showing second silver image data; FIG. 31 is a diagram showing input image data composed of the data shown in FIGS. 5 to 9 and FIGS. 28 to 30; FIG. It is a table|surface which shows the evaluation result in each Example.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing the overall configuration of an image forming apparatus 1 to which an image processing section according to an embodiment of the invention is applied. FIG. 2 is a diagram showing the main part of the control system of the image forming apparatus 1. As shown in FIG.

The image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 primarily transfers each color toner image of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 onto the intermediate transfer belt 421, An image is formed by superimposing the four-color toner images on the intermediate transfer belt 421 and then secondary-transferring them to the paper S. FIG.

In the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 421 in one procedure. A tandem system is used.

As shown in FIG. 2, the image forming apparatus 1 includes an image reading section 10, an operation display section 20, an image processing section 30 as an example of an image processing device, an image forming section 40, a paper conveying section 50, a fixing section 60, and a control unit. A unit 101 is provided.

The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, and the like. The CPU 102 reads out a program corresponding to the processing content from the ROM 103, develops it in the RAM 104, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 are referred to. The storage unit 72 is composed of, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 101 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. . For example, the control unit 101 receives image data transmitted from an external device, and forms an image on the sheet S based on this image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

As shown in FIG. 1, the image reading section 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

The automatic document feeder 11 transports the document D placed on the document tray by the transport mechanism and sends it to the document image scanning device 12 . The automatic document feeder 11 makes it possible to continuously read images (including both sides) of a large number of documents D placed on the document tray at once.

The document image scanning device 12 optically scans the document conveyed onto the contact glass from the automatic document feeder 11 or the document placed on the contact glass, and converts the reflected light from the document into a CCD (Charge Coupled Device). ) An image is formed on the light-receiving surface of the sensor 12a, and the document image is read. The image reading unit 10 generates input image data based on the result of reading by the document image scanning device 12 . Predetermined image processing is performed on the input image data in the image processing section 30 .

As shown in FIG. 2 , the operation display unit 20 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22 . The display unit 21 displays various operation screens, image states, operation states of respective functions, and the like according to display control signals input from the control unit 101 . The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs operation signals to the control unit 101 .

The image processing unit 30 includes a circuit or the like that performs digital image processing on input image data in accordance with initial settings or user settings. For example, the image processing unit 30 performs tone correction based on tone correction data (tone correction table) under the control of the control unit 101 . The image processing unit 30 also performs various types of correction processing such as color correction and shading correction, compression processing, etc., on the input image data, in addition to tone correction. The image forming section 40 is controlled based on the image data subjected to these processes. Details of the image processing unit 30 will be described later.

As shown in FIG. 1, the image forming section 40 includes image forming units 41Y, 41M, and 41C for forming an image using colored toners of Y, M, C, and K components based on input image data. , 41K, an intermediate transfer unit 42, and the like.

Image forming units 41Y, 41M, 41C, and 41K for the Y, M, C, and K components have similar configurations. For convenience of illustration and description, common components are indicated by the same reference numerals, and Y, M, C or K is added to the reference numerals when they are distinguished from each other. In FIG. 1, only the components of the image forming unit 41Y for the Y component are denoted by reference numerals, and the components of the other image forming units 41M, 41C, and 41K are omitted.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

The photoreceptor drum 413 is made of, for example, an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal substrate.

The control unit 101 rotates the photoreceptor drum 413 at a constant peripheral speed by controlling the drive current supplied to a drive motor (not shown) that rotates the photoreceptor drum 413 .

The charging device 414 is, for example, a scorotron, and uniformly charges the surface of the photosensitive drum 413 having photoconductivity to negative polarity by generating corona discharge.

The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to an image of each color component. As a result, an electrostatic latent image of each color component is formed on the image area irradiated with the laser light on the surface of the photosensitive drum 413 due to the potential difference from the background area.

The developing device 412 is a two-component reversing type developing device, and forms a toner image by visualizing an electrostatic latent image by attaching developer of each color component to the surface of the photosensitive drum 413 .

To the developing device 412, for example, a DC developing bias having the same polarity as the charging polarity of the charging device 414 or a developing bias in which a DC voltage having the same polarity as the charging polarity of the charging device 414 is superimposed on an AC voltage is applied. As a result, reversal development is performed to attach toner to the electrostatic latent image formed by the exposure device 411 .

The drum cleaning device 415 is in contact with the surface of the photoreceptor drum 413 and has a flat drum cleaning blade 415A made of an elastic material. remove the toner.

Further, in this embodiment, an image forming unit 41T for white toner is provided. The image forming unit 41T has the same configuration as the image forming unit 41 for other color toners, and is arranged at a position where white toner can be supplied to the upper layer of the color toner. The white toner is also used to form a base image on the sheet S for additional printing, which will be described later.

The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

The intermediate transfer unit 42 is composed of an endless belt, and is looped around a plurality of support rollers 423 . At least one of the plurality of supporting rollers 423 is configured as a driving roller, and the others are configured as driven rollers. For example, it is preferable that the roller 423A arranged on the downstream side in the belt running direction of the primary transfer roller 422 for the K component is a driving roller. This makes it easier to keep the running speed of the belt constant in the primary transfer nip. As the drive roller 423A rotates, the intermediate transfer belt 421 runs in the arrow A direction at a constant speed.

The intermediate transfer belt 421 is a belt having conductivity and elasticity, and is rotationally driven by a control signal from the control section 101 .

The primary transfer roller 422 is arranged on the inner circumferential surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. A primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421 is formed by pressing the primary transfer roller 422 against the photosensitive drum 413 with the intermediate transfer belt 421 therebetween.

The secondary transfer roller 424 is arranged on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B arranged on the downstream side of the drive roller 423A in the belt running direction. A secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the sheet S is formed by pressing the secondary transfer roller 424 against the backup roller 423B with the intermediate transfer belt 421 therebetween.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photosensitive drum 413 are sequentially superposed on the intermediate transfer belt 421 and primarily transferred. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421, that is, the side in contact with the primary transfer roller 422, thereby forming a toner image. is electrostatically transferred to the intermediate transfer belt 421 .

After that, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred onto the sheet S. FIG. Specifically, a secondary transfer bias is applied to the backup roller 423B, a charge of the same polarity as the toner is applied to the surface side of the sheet S, that is, the side that contacts the intermediate transfer belt 421, and the secondary transfer roller By applying a voltage to 424 that has a relatively higher potential than the backup roller 423B, the toner image is electrostatically transferred to the sheet S, and the sheet S is conveyed toward the fixing section 60. .

A belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after secondary transfer. Instead of the secondary transfer roller 424, a so-called belt-type secondary transfer unit may be employed in which a secondary transfer belt is stretched in a loop shape around a plurality of support rollers including the secondary transfer roller. .

The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member arranged on the fixing surface of the paper S, that is, the surface on which the toner image is formed, and the rear surface of the paper S, that is, arranged on the surface opposite to the fixing surface. It includes a lower fixing section 60B having a back side support member to which a heat source 60C is attached, and a heat source 60C. A fixing nip for nipping and conveying the sheet S is formed by pressing the back surface side support member against the fixing surface side member.

The fixing unit 60 fixes the toner image to the paper S by heating and pressurizing the paper S conveyed after the toner image is secondarily transferred at the fixing nip. The fixing section 60 is arranged inside the fixing device F as a unit.

The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. The three paper feed tray units 51a to 51c that constitute the paper feed unit 51 store paper S (standard paper, special paper) identified based on basis weight, size, etc., for each preset type. . The transport path portion 53 has a plurality of transport rollers such as a registration roller body 53a.

The paper sheets S accommodated in the paper feed tray units 51 a to 51 c are sent out one by one from the top and conveyed to the image forming section 40 by the conveying path section 53 . At this time, the skew of the fed sheet S is corrected and the transport timing is adjusted by the registration roller section in which the registration roller pair 53a is arranged. Then, in the image forming section 40 , the toner images on the intermediate transfer belt 421 are collectively secondary-transferred onto one surface of the sheet S, and the fixing section 60 performs a fixing process. The sheet S on which the image has been formed is discharged out of the apparatus by the discharge roller 52a.

Next, additional printing will be described.
Since the background color of the recording medium used for packages and the like is often not white, for example, when an image is printed on the recording medium using the four colors of YMCK, there are many cases where the target color in the image cannot be reproduced.

When printing an image on such a recording medium, for example, a white base image is formed on the recording medium, and then an overlying image of another color is formed on the recording medium on which the base image has been formed. done. By forming the upper layer image on the base image by the additional printing, it becomes possible to reproduce the target color in the upper layer image.

In the additional printing, image forming operations such as image formation, transfer, and fixation on a recording medium are performed multiple times for a base image and an upper layer image. A pattern in which additional printing is performed corresponds to a case where the order of arrangement of the image forming units 41 does not match the order in which the base image and the upper layer image are superimposed on the recording medium.

For example, in the present embodiment, when white toner is used for the base image, the image forming units 41 are arranged such that the white toner is on top of the colored toner. Therefore, when forming an image on the recording medium, the image forming operation is performed a plurality of times for the base image and the upper layer image.

For example, an example of forming images G1, G2, and G3 on a recording medium S1 having a colored background as shown in FIG. 3 will be described. The color of the recording medium S1 shown in FIG. 3 is, for example, red, and its colorimetric values are L* value of 29, a* value of 48, and b* value of 21.

The image G1 is a star-shaped image, and is composed of a K-color star-shaped edge G11 (displayed with light dots) and a star G12 (displayed with dark dots) obtained by synthesizing Y, M, and C colors. ing. The image G2 is a star-shaped image composed only of Y color. The image G3 is a white toner character image composed of "IMAGE". In the example shown in FIG. 3, it is assumed that a background image is formed with white toner on the image G1. The amount of white toner used for the background image corresponds to, for example, an L* value of 80, an a* value of 0.2, and a b* value of 0.6.

When forming such images G1, G2, and G3 on the recording medium S1, in the image forming apparatus 1 according to the present embodiment, among the image forming units 41 shown in FIG. Images are formed in order.

As shown in FIG. 4, the white image forming unit 41T forms an image corresponding to the first white image data T1 composed of the white character image of the image G3. As shown in FIG. 5, the Y-color image forming unit 41Y forms an image corresponding to the Y-color image data Y1 composed of the star portion G12 of the image G1 and the image G2.

As shown in FIG. 6, the M-color image forming unit 41M forms an image corresponding to the M-color image data M1 composed of the star portion G12 of the image G1. As shown in FIG. 7, the C-color image forming unit 41C forms an image corresponding to the C-color image data C1 composed of the star portion G12 of the image G1. As shown in FIG. 8, the K-color image forming unit 41K forms an image corresponding to the K-color image data K1 formed by the edge G11 of the image G1.

Further, a base image G4 is formed as a base of the image G1 at a timing different from that of each image shown in FIGS. The base image G4 is formed with white toner, for example. In this case, as shown in FIG. 9, the white toner image forming unit 41T forms an image corresponding to the second white image data T2 composed of the base image G4. The image data shown in FIGS. 4 to 9 are formed by inputting data created by a PC (Personal Computer) or the like into the image forming apparatus 1, for example.

In the recording medium S1 shown in FIG. 3, since the background color is colored, the base image G4 is first formed on the recording medium S1, and then the upper layer images G1, G2, and G3 are formed on the recording medium S1. It is formed.

For example, as shown in FIG. 10, when each image data exists as input image data, the image data corresponding to the image forming unit 41 that performs the image forming operation is sequentially output to the image processing section 30 . Specifically, the second white image data T2, the first white image data T1, the Y color image data Y1, the M color image data M1, the C color image data C1, and the K color image data K1 are image-processed in this order.

The image corresponding to the second white image data T2, which is the background image G4, is fixed on the recording medium S1 before the other images. Each image corresponding to the first white image data T1, the Y-color image data Y1, the M-color image data M1, the C-color image data C1, and the K-color image data K1 is superimposed on the intermediate transfer belt 421 or the like, and then transferred to the background image. The image G4 is transferred onto the fixed recording medium S1.

Next, details of the image processing unit 30 according to the present embodiment will be described. FIG. 11 is a block diagram showing the image processing section 30 according to this embodiment.

The image processing unit 30 includes a CPU, a ROM, a RAM, and the like, and performs image processing related to the additional printing described above. The CPU reads a program corresponding to the processing content from the ROM, develops it in the RAM, and centrally controls the operation of the image processing section 30 in cooperation with the developed program.

Specifically, as shown in FIG. 11, the image processing section 30 has a specifying section 31, a processing section 32, a selecting section 33, and an order determining section .

The specifying unit 31 specifies the background image based on the input image data. More specifically, for example, when there is input image data for each image shown in FIG. 10, the specifying unit 31 specifies image data related to the base image from among the input image data.

The specifying unit 31 specifies, for example, a white image (special color image) positioned within the specified area in the input image data as the background image. The designated area is an area corresponding to the upper layer image G1 in the case of the input image data shown in FIG. The specified area may be an area specified by the user, or may be an area specified in advance.

The specifying unit 31 specifies the contour portion of the background image from the image data related to the background image.

The processing unit 32 performs image processing for superimposing an upper layer image and a base image, which is the base of the upper layer image, on the same recording medium by reprinting, that is, forming images a plurality of times. The processing unit 32 adds a border image having the same color as the background portion of the upper layer image to the portion of the upper layer image that matches the contour portion of the base image specified by the specifying unit 31 .

The background portion is, for example, the color of the recording medium, or, if the recording medium is transparent, the color according to the mode of use of the recording medium after the image is formed. The color corresponding to the usage of the recording medium is, for example, the color of the object behind the recording medium on which the image is formed. This is because, in the case of a transparent recording medium, the color of the object placed behind the recording medium becomes the background color of the upper layer image through the recording medium. Note that the recording medium is not limited to a sheet such as paper, and may be any medium as long as it is an image-formable medium.

Further, the color equivalent to the color of the background portion includes not only the same color as the background portion color, but also a color within a predetermined difference from the same color (for example, the color difference ΔE is 3 or less). Also, the predetermined difference can be changed as appropriate by the user.

The processing unit 32 adds a border image to a range of a predetermined width from the boundary between the image portion and the non-image portion in the upper layer image data toward the non-image portion side. The image portion is a portion in which the pixel value of any color is greater than 0 among all the colors used for the upper layer image in the image data. The non-image portion is a portion in which the pixel values of all the colors used in the image data are all zero.

The predetermined width is, for example, 0.8 mm, and can be appropriately set to a width in consideration of a portion where the base image protrudes from the upper layer image due to misalignment.

In overprinting, when a base image and an upper layer image are superimposed on a recording medium, positional deviation may occur in which the transfer position of the base image and the transfer position of the upper layer image deviate. The misregistration occurs due to performing image formation a plurality of times with the base image and the upper layer image at the time of additional printing. Specifically, as a cause of positional deviation, there is a case where the timing at which the portion of the recording medium to be reprinted passes the position of the transfer nip slightly deviates each time an image is formed.

Further, as a cause of positional deviation, there is a case where the size of the image formed on the recording medium expands or contracts with respect to the design value in the first image formation. This is due to heat in the image forming apparatus 1 using heat fixing as in the present embodiment, and due to moisture in the ink in the image forming apparatus using ink.

For example, as shown in FIG. 12, assume that there is image data related to an upper layer image G5. For example, if this upper layer image G5 is printed on a colored print medium S1 as shown in FIG. have different colors.

Therefore, as shown in FIG. 14, after forming a base image G6 having the same size as the upper layer image G5 on the recording medium S1, the upper layer image G5 is formed on the recording medium S1. However, when a positional deviation occurs between the upper layer image G5 and the base image G6, an image defect occurs in which a portion G61 where the base image G6 protrudes from the upper layer image G5 exists.

Therefore, in the present embodiment, as shown in FIG. 15A, the processing unit 32 performs a process of adding a border image G7 surrounding the upper image G5. The edge image G7 is formed with a predetermined width G71 outside each side of the upper layer image G5. Therefore, as shown in FIG. 15B, the portion G61 where the background image G6 protrudes can be hidden by the edge image G7, so that the above image defect can be made inconspicuous.

As shown in FIG. 11, the selection unit 33 selects the color of the edge image from predetermined options. The predetermined options are, for example, a plurality of color options pre-stored in the image forming apparatus 1 .

Specifically, the selection unit 33 selects the color closest to the color of the background portion as the color of the edge image from the predetermined options based on the user's instruction.

The selection unit 33 controls to present predetermined options to the user, for example, display them on the display unit 22 . Then, as shown in FIG. 16, predetermined options are displayed on the display unit 22 . FIG. 16 shows an example in which the colors in the options are black, red, and dark blue.

When the user looks at the display unit 22 and selects a color associated with the option, the selection unit 33 selects the color based on the command from the display unit 22 as the color of the edge image. For example, when the color of the recording medium is black, the user selects black having a predetermined color value from the options, thereby setting the edge image G7 to the same color as the color of the recording medium.

By doing so, the color selected by the user as a color close to the background portion can be used as the color of the edge image, and the degree of freedom of the color of the edge image G7 can be improved.

Note that the colors in the options can be appropriately set according to the recording medium on which the image is to be formed.

When the specifying unit 31 specifies the base image, the order determining unit 34 determines the output order of the base image and the upper layer image. For example, when the paper type is a recording medium such as colored paper, the order determination unit 34 determines the output order so that the base image is output before the upper layer image. Also, when the paper type is a recording medium such as a transparent film, the order determination unit 34 determines the output order so that the base image is output after the upper layer image. By doing so, it is possible to form images on the recording medium in a desired order.

Next, an operation example when executing image processing control in the image processing unit 30 will be described. FIG. 17 is a flow chart showing an operation example of image processing control in the image processing section 30 . The processing in FIG. 17 is appropriately executed, for example, when the control unit 101 of the image forming apparatus 1 receives a print job execution instruction.

As shown in FIG. 17, the image processing unit 30 acquires input image data (step S101). Next, the image processing unit 30 determines whether or not there is image data of a background image in the input image data (step S102).

As a result of determination, if there is no background image (step S102, NO), the process transitions to step S107. On the other hand, if there is a background image (step S102, YES), the image processing section 30 outputs the background image to the recording medium (step S103).

Next, the image processing unit 30 determines whether or not additional printing has started (step S104). The start of additional printing means, for example, that the recording medium on which the base image is formed is placed again in the paper feed unit 51 or the like, and the image formation of the upper layer image is started on the recording medium.

If the result of determination is that additional printing has not started (step S104, NO), the process of step S104 is repeated. On the other hand, if additional printing has started (step S104, YES), the image processing unit 30 determines whether or not the color of the background portion of the recording medium has been obtained (step S105).

As a result of determination, when the color of the background portion has not been acquired (step S105, NO), the process of step S105 is repeated. On the other hand, if the color of the background portion has been acquired (step S105, YES), the image processing unit 30 performs processing to add the edge image to the image data (step S106).

Next, the image processing unit 30 outputs the upper layer image to the recording medium (step S107). The upper layer image in step S107 does not have an edge image if it is determined NO in step S102, and it has an edge image if it is after step S106. After step S107, this control ends.

According to the present embodiment configured as described above, it is possible to hide the portion where the base image protrudes from the upper layer image by the edge image, so that the above image defect can be made inconspicuous. As a result, it is possible to reduce the occurrence of image defects caused by misalignment between the upper layer image and the base image.

In addition, since the edge image is formed within a predetermined width from the boundary between the image portion and the non-image portion of the upper layer image, it is possible to sufficiently leave the texture on the surface of the recording medium. For example, Japanese Patent Application Laid-Open No. 2008-65156 discloses a technique of forming toner of the same color as the paper on the entire paper and forming an image thereon. This will damage the texture of the paper.

On the other hand, in the present embodiment, the texture of the surface of the recording medium can be sufficiently preserved in the portion where the upper layer image and the edge image are not formed, so that the desired print including the texture of the recording medium can be created. can do.

In the above embodiment, the base image is output to the recording medium as it is in the size of the input image data. It may be larger than the image.

Specifically, as shown in FIG. 18A, the processing unit 32 selects a range larger than the data base image G62 (chain line) on the image data specified by the specifying unit 31 and to which the border image G7 is added. The size of the base image G6 (solid line) is changed so that the size fits within.

The processing unit 32 processes the base image G6 so that a border narrower than the width of the border image G7 is added from the boundary (position on the two-dot chain line) between the image part and the non-image part in the data base image G62. resize the . The image portion is a portion in which the pixel value relating to white used in the data background image G62 is greater than zero. The non-image portion is a portion where the pixel value for white used in the data background image G62 is 0, and is a portion outside the chain double-dashed line.

In the background image G6, the width added to the data background image G62 is, for example, 0.5 mm, and can be appropriately set in consideration of the width of the edge image G7.

When the positional deviation occurs, in addition to the occurrence of a portion G61 where the base image G6 protrudes from the upper layer image G5, as shown in FIG. 18B, there is a portion G51 where the base image G6 does not exist in the upper layer image G5. The portion G51 may be determined to be an image defect depending on the color tone when the upper layer image G5 and the recording medium S1 are superimposed, or depending on the user.

However, as shown in FIG. 18A, by increasing the size of the base image G6, it is possible to suppress occurrence of a portion G51 in the upper layer image G5 where there is no base image G6. As a result, it is possible to make the above-described image defects less conspicuous, thereby reducing the occurrence of image defects caused by misalignment between the upper layer image G5 and the base image G6.

Further, in the above-described embodiment, only the edge image G7 having a certain color is added to the upper layer image G5, but the present invention is not limited to this. The processing unit 32 may perform smoothing processing so that the gradation distribution in the edge region of the edge image becomes smaller toward the edge of the edge image.

By performing the smoothing process, the processing unit 32 adjusts the size of the edge image. Specifically, as shown in FIG. 19, the processing unit 32 performs a process of adding a first edge image G8 adjacent to the upper layer image G5. The first edge image G8 is an image having the same width as the edge image G7 described above.

Then, the processing unit 32 performs a process of adding a second edge image G9 adjacent to the first edge image G8 on the side opposite to the upper layer image G5, and performs a smoothing process on the second edge image G9. The second edge image G9 on the image data has the same width as the first edge image G8.

Here, as shown in FIG. 20, a specific example of smoothing processing will be described with reference to an enlarged view of a portion where the second edge image G9 and the first edge image G8 are arranged horizontally from the left. FIG. 20 shows only the second edge image G9 and the first edge image G8 at arbitrary positions in the vertical direction.

In the second edge image G9, the left end position is position A1 in the image data, and the right end position is position A2. The first edge image G8 has a left end position A2 in the image data and a right end position A3. An upper layer image G5 is located on the right side of the position A3. The gradation value in the image data of the first edge image G8 and the second edge image G9 is X1.

As shown in FIG. 21, the processing unit 32 adjusts the gradation distribution of the portion corresponding to the predetermined range in the second edge image G9, including the boundary between the image portion in the second edge image G9 and the non-image portion in the upper layer image data. is smoothed.

The image part here is the part of the second edge image G9, and is the part where the pixel value of any color is greater than 0 among all the colors used in the second edge image G9. The non-image portion is a portion on the left side of the position A1, in which the pixel values of all colors in the image data are 0. The predetermined range is, for example, the range from position A2 to position A1, which is the range of the entire second edge image G9 on the image data.

The processing unit 32 smoothes the second edge image G9 so that the gradation distribution of the second edge image G9 decreases in the direction opposite to the upper layer image G5, that is, in the direction from the position A2 to the position A1. process.

The processing unit 32 acquires the gradation distribution in the range from the position A1 to the position A2, and calculates the average value of the gradation values within that range. Since the gradation values from position A1 to position A2 are all X1, the average value is X1. A solid line in FIG. 21 indicates the gradation distribution in the input image data.

The processing unit 32 performs smoothing processing so that the predetermined range, that is, the gradation distribution from the position A1 to the position A2, conforms to a normal distribution whose vertex is the boundary between the first edge image G8 and the second edge image G9. . Specifically, the processing unit 32 performs image processing so that the gradation value decreases toward the outside of the second edge image G9 with the position A2 as a peak (see the broken line). The gradation value of the second edge image G9 at position A2 is assumed to be X1, which is the above average value.

Also, at position A1, which is the position of the boundary, the gradation value changes so that the gradation value is X2, which is 50% of X1. As a result, the horizontal length of the smoothed second edge image G9 is about twice the length of the second edge image G9 on the image data.

By doing so, as shown in FIG. 22, the edges of the edge image are blurred. Therefore, it is possible to make the boundary between the edge image and the recording medium less conspicuous due to the subtle color difference between the edge image and the recording medium, and as a result, the image can be displayed with high image quality.

In the above description, gradation was exemplified as a parameter for smoothing, but the present invention is not limited to this, and any parameter related to at least one of color and brightness can be used. good. Such a parameter may be, for example, brightness or luminance, in addition to gradation. Also, as described above, for example, only gradation may be smoothed, or a plurality of gradations, brightness, and luminance may be smoothed.

Further, as shown in FIG. 23, the processing unit 32 changes the gradation distribution to either the inside (dashed line W1) or the outside (dashed line W2) of the second edge image with respect to the boundary based on a predetermined condition. It is also possible to move to .

Also, the processing unit 32 may adjust the predetermined range according to predetermined conditions. Specifically, as shown in FIG. 24, the processing unit 32 may adjust the predetermined range to either a narrower side (broken line W3) or a wider side (broken line W4) based on a predetermined condition. good.

The predetermined conditions include parameters indicating at least one of the color and brightness of the recording medium (e.g., brightness, brightness, gradation) and parameters indicating at least one of the color and brightness of the upper layer image (e.g., brightness, brightness). , gradation).

For example, when the color of the recording medium is relatively dark, the background image protruding from the upper layer image is more noticeable, so the processing section 32 adjusts the high density area of the second edge image to widen. For example, in the case of the example shown in FIG. 23, the processing section 32 moves the gradation distribution to the outside of the second edge image. Moreover, in the case of the example shown in FIG. 24, the processing unit 32 adjusts to narrow the smoothing range.

By doing so, it is possible to further make the background image protruding from the upper layer image less conspicuous.

Further, when the gloss difference between the upper layer image and the recording medium is large enough to be visually recognized by the user, if the width of the edge image is wide, the edge image may be easily visible due to the gloss difference. In this case, the processing unit 32 adjusts so that the second edge image is narrowed or blurred. For example, in the case of the example shown in FIG. 23, the processing unit 32 moves the gradation distribution inside the second edge image. Moreover, in the case of the example shown in FIG. 24, the processing unit 32 adjusts to narrow the smoothing range.

By doing so, it is possible to further obscure the portion of the upper layer image that does not have the base image.

Note that the adjustment of the size of the second edge image is not limited to the pattern described above, and can be appropriately changed depending on the color of the upper layer image, the color of the recording medium, and the like.

Further, in the above embodiment, the color selected by the selection unit 33 is set as the color of the edge image, but the present invention is not limited to this. For example, if it is possible to acquire the detection information of the color of the recording medium, the processing section 32 may determine the color of the edge image G7 based on the detection information.

The color of the recording medium may be detected by, for example, providing the image forming apparatus 1 with a detection unit capable of detecting the color of the recording medium, or the color may be detected by the detection unit outside the image forming apparatus 1 in advance. can be

After acquiring the detection information of the color of the recording medium, the processing unit 32 calculates the color gradation of the background portion that is realized by the predetermined illumination light on the base image of the white toner, and calculates the calculated gradation. be the color of the edge image.

By doing so, as shown in FIG. 25, the color of the edge image G7 and the color of the recording medium S1 can be substantially matched. can be made even less noticeable.

Further, in the above embodiment, the base image is formed with white toner, but the present invention is not limited to this, and silver toner may be used.

When the silver toner is used for the base image G6, it is possible to reproduce a metallic texture in the upper layer image G5.

However, as shown in FIG. 26, by forming the edge image G7, the portion protruding from the upper layer image G5 can be hidden by the edge image G7. can.

Further, in the above embodiment, the range in which the edge image G7 is provided is the non-image portion. However, for example, another image portion may exist in the range of the edge image G7. Another image portion is an image in which the pixel value of any color is greater than 0 among all the colors of the image data.

Examples of the presence of another image portion include, for example, a case where another image G52 exists in a range narrower than a predetermined width G71 in the vicinity of the upper layer image G5 as shown in FIG. This is the case where there is a gap G53 narrower than the predetermined width G71 inside the image G5.

In such a case, if the edge image G7 is formed with a predetermined width, the edge image G7 and another image portion will overlap. For example, in the case of FIG. 27A, when the edge image G7 having the predetermined width G71 is formed, another image portion G52 overlaps the edge image G7 (see broken line). Further, in the case of FIG. 27B, the edge image G7 is formed in a range wider than the gap G53, and overlaps the upper layer image G5 and the edge image G7 on the opposite side of the gap G53 (see the broken line). Note that FIG. 27B shows an example in which the edge image G7 is formed with reference to the left side of the gap G53.

Therefore, when the image portion is positioned within a predetermined width G71 on the non-image portion side from the boundary, the processing section 32 corrects the edge image G7 so that the image portion and the edge image G7 do not overlap.

By doing so, it is possible to suppress overlap between the edge image G7 and the image portion, so that it is possible to easily form a desired image.

Further, in each of the above-described embodiments, either one of white toner and silver toner is used for the background image, but the present invention is not limited to this. For example, more than one color may be used for the background image.

In such a case, the image forming apparatus 1 may be further provided with an image forming unit for silver toner. Image data in this case is formed in the same manner as in the case of FIGS.

For example, in the images G1, G2, and G3 shown in FIG. 3, an example in which the image G1 is formed with a white toner base image and the image G2 is formed with a silver toner base image will be described. In the image G3, the image shown in FIG. 3 is formed on the recording medium S1, with the characters "IMAGE" having "AGE" as a character image G31 using white toner and "IM" as a character image G32 using silver toner. shall be

As shown in FIG. 28, the white image forming unit 41T forms an image corresponding to the first white image data T1 composed of the character image G31 of the image G3. As shown in FIG. 29, the silver image forming unit forms an image corresponding to the first silver image data T3 composed of the character image G32 of the image G3. Y-color image data Y1, M-color image data M1, C-color image data C1, and K-color image data K1 are the same as in FIGS.

In addition to the base image G4, a base image G10 is formed as a base of the image G1 at a timing different from that of the images shown in FIGS. The base image G10 is formed with silver toner. In this case, as shown in FIG. 30, the silver toner image forming unit forms an image corresponding to the second silver image data T4 composed of the background image G10. The second white image data T2 is the same as in FIG.

Since the recording medium S1 shown in FIG. 3 has a colored background, the base images G4 and G10 are first formed on the recording medium S1, and then the upper layer images G1, G2, and G3 are formed on the recording medium. It is formed in S1.

For example, as shown in FIG. 31, when each image data exists as input image data in the same manner as in FIG. To go. Specifically, second white image data T2, second silver image data T4, first white image data T1, first silver image data T3, Y color image data Y1, M color image data M1, C color image data C1. , K-color image data K1.

As a result, the image corresponding to the second silver image data T4, which is the background image G10 as well as the background image G4, is fixed on the recording medium S1 before the other images, and the other image is fixed to the background image G10. It is transferred to the fixed recording medium S1.

In addition, in the above-described embodiment, the identifying unit 31 identifies the white image positioned within the specified area in the input image data as the background image, but the present invention is not limited to this.

For example, the specifying unit 31 may specify, in the input image data, a spot color image positioned within a color-specified region in which a spot color is specified as the background image. For example, in the case of the input image data shown in FIG. 3, the area of the upper layer image G1 is set as the color designation area, and white is designated as the special color in the color designation area. 9 is specified as the background image. Even in this way, the specifying unit 31 can specify the background image in the input image data.

In addition, the specifying unit 31 stores, in the input image data, a first special color image formed at a timing different from that of the other colors, and a second special color image formed at the same timing as the other colors and having the same color as the first special color image. If there is a spot color image, the first spot color image may be specified as the base image. For example, in the case of the input image data shown in FIG. 3, it is not necessary to match the outline portion of the image G3, which is formed at a timing different from that of the base image G4, to the upper layer image. Therefore, the specifying unit 31 specifies only the image data T2 related to the background image G4 as the background image. Even in this way, the specifying unit 31 can specify the background image in the input image data.

In the above-described embodiment, the image processing unit 30 includes the specifying unit 31, the processing unit 32, the selecting unit 33, and the order determining unit 34. However, the present invention is not limited to this. The unit 31, the processing unit 32, the selection unit 33, and the order determination unit 34 may be provided separately.

Further, although the image processing section 30 is incorporated in the image forming apparatus 1 in the above embodiment, the present invention is not limited to this, and the image processing section 30 may be incorporated in an apparatus other than the image forming apparatus 1. Also good.

In addition, each of the above-described embodiments is merely an example of specific implementation of the present invention, and the technical scope of the present invention should not be construed to be limited by these. Thus, the invention may be embodied in various forms without departing from its spirit or essential characteristics.

Finally, using the image forming apparatus 1 shown in FIG. 1, an evaluation experiment was conducted to confirm the effectiveness of the present invention by having a user confirm the image output in each of the above embodiments. FIG. 32 is a table showing evaluation results in each example.

Example 1 in FIG. 32 is an example in which a process of adding a border image to an upper layer image is performed without changing the size of the base image with white toner. Example 2 in FIG. 32 is an example in which the size of the background image with white toner is changed, and the process of adding a border image to the upper layer image is performed. Example 3 in FIG. 32 is an example in which the size of the background image with white toner is changed, and a smoothed edge image is added to the upper layer image. The colors of the edge images in Examples 1, 2, and 3 are colors selected by the user from predetermined options.

Example 4 in FIG. 32 is an example in which the size of the background image with white toner is changed, and a smoothed border image is added to the upper layer image. In this embodiment, the color is set based on the color detection information of the recording medium. Example 5 in FIG. 32 is an example in which the size of the background image made of silver toner is changed and a border image is added to the upper layer image. This is an embodiment in which the color is set to only one color.

In Comparative Examples 1 and 2 in FIG. 32, the input image data is directly output to the recording medium. Comparative Example 1 uses a white toner for the base image, and Comparative Example 2 uses a silver toner for the base image.

Also, "x" in FIG. 32 indicates that the image is determined to be defective. "○" indicates that the image was judged to be a good image, and "⊚" indicates that it was judged to be the best image among the images in all the examples.

As shown in FIG. 32, in the case of Comparative Example 1, since the protruding portion of the white base image was conspicuous, it was determined that the image was defective. In the case of Comparative Example 2, the protruding portion of the silver base image had a high reflectance, and depending on the environmental conditions under which the user checked the recording medium, the portion looked white and conspicuous.

On the other hand, the images of Examples 1 to 5 were all judged to be good images. In particular, in Example 4, the color of the edge image is set to a color based on the detection information of the color of the recording medium, and the boundary between the edge image and the background is blurred. It became difficult to distinguish from the medium, and was judged to be the best image. From the above, the effectiveness of the present invention was confirmed.

1 image forming apparatus 30 image processing unit 31 identification unit 32 processing unit 33 selection unit 34 order determination unit

Claims (20)

a processing unit that performs image processing when forming an upper layer image and a base image, which is the base of the upper layer image, on the same recording medium by forming images a plurality of times;
a specifying unit that specifies the base image based on the input image data;
with
The processing unit adds a border image having the same color as the background portion of the upper layer image to a portion of the upper layer image that matches the contour portion of the base image specified by the specifying unit. stomach,
When the recording medium is transparent, the color of the background portion is a color according to the mode of use of the recording medium after the image is formed.
Image processing device. a processing unit that performs image processing when forming an upper layer image and a base image, which is the base of the upper layer image, on the same recording medium by forming images a plurality of times;
a specifying unit that specifies the base image based on the input image data;
with
The processing unit adds a border image having the same color as the background portion of the upper layer image to a portion of the upper layer image that matches the contour portion of the base image specified by the specifying unit. ,
The color of the background portion is the color of the recording medium,
Image processing device. The edge image is composed of a color that is the same as the color of the background portion of the upper layer image and that is different from the color of the upper layer image.
The image processing apparatus according to claim 2. In the image data of the upper-layer image, the processing unit is configured to generate an image portion having a pixel value greater than 0 for any color among all colors of the upper-layer image, and an image portion having pixel values of all colors of the image data adding the edge image to a range of a predetermined width from a boundary with a non-image portion that is 0 toward the non-image portion side;
The image processing apparatus according to any one of claims 1 to 3 . When an image having a pixel value greater than 0 associated with any of all colors associated with the image data is located within the range of the predetermined width from the boundary toward the non-image area, the processing unit correcting the edge image so that it does not overlap the image;
The image processing apparatus according to claim 4 . The processing unit adjusts the base image so that it is larger than the data base image of the same size as the upper layer image specified by the specifying unit and is within the range to which the edge image is added. resize,
The image processing apparatus according to any one of claims 1 to 5 . The processing unit distributes the data base image from a boundary between a non-image portion having a pixel value of 0 and an image portion having a pixel value greater than 0 to the non-image portion. resizing the background image so that a border of the same color as the background image is added;
The image processing apparatus according to claim 6 . a selection unit that selects a color closest to the color of the background from among predetermined options as the color of the edge image based on a user's instruction;
The image processing apparatus according to any one of claims 1 to 7 . The selection unit performs control to present the predetermined option to the user,
The image processing apparatus according to claim 8. The processing unit acquires detection information of the color of the background portion, and determines the color of the edge image based on the detection information.
4. The image processing apparatus according to claim 2 or 3 . The processing unit performs a smoothing process such that a parameter related to at least one of color and brightness in an edge region of the edge image becomes smaller toward the edge of the edge image.
The image processing apparatus according to any one of claims 1 to 10. The processing unit adjusts the size of the edge image by the smoothing process.
The image processing apparatus according to claim 11. The processing unit is
adding a first edge image adjacent to the upper layer image and a second edge image adjacent to the first edge image on the opposite side of the first edge image to the upper layer image;
performing the smoothing process on the second edge image;
The image processing apparatus according to claim 11 or 12. In the image data of the second border image, the processing unit is configured to: out of all colors used in the second border image, an image part in which the pixel value of any color is greater than 0; Performing the smoothing process so as to follow a normal distribution for a predetermined range including a boundary with a non-image portion that is 0;
The image processing apparatus according to claim 13. The processing unit performs the smoothing process so that a boundary between the first edge image and the second edge image becomes a vertex of the normal distribution.
The image processing apparatus according to claim 14. The processing unit changes the predetermined range so as to adjust the size of the second edge image according to a predetermined condition.
16. The image processing apparatus according to claim 14 or 15. The processing unit adjusts the distribution of the parameter to either the inner side or the outer side of the second edge image with respect to the boundary so as to adjust the size of the second edge image according to a predetermined condition. to move
The image processing apparatus according to any one of claims 14-16. The specifying unit specifies, in the input image data, a spot color image located within a specified area or a spot color image located within a color specified area in which a spot color is specified as a background image.
The image processing device according to any one of claims 1 to 17. When the input image data includes a first special color image formed at a timing different from that of the other colors and a second special color image formed at the same timing as the other colors, the specifying unit performs 1 specifying a special color image as the background image;
The image processing apparatus according to any one of claims 1 to 18. an order determination unit that determines an output order of the base image and the upper layer image when the base image is specified by the specifying unit;
The image processing apparatus according to any one of claims 1 to 19.

Images