JP2010026130A - Image forming apparatus, image forming method and printing medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a color print with high texture which provides a high-saturation color reproduced image, while maintaining sharpness. <P>SOLUTION: A sticking processing part 306 extracts an edge amount for each pixel of RGB signal and decides whether to make a light-transmitting medium stick to a light-reflecting medium for each pixel, based on the edge amount. When the edge amount is equal to or larger than a predetermined threshold, the pixel is stuck; and when the edge amount is lower than the predetermined threshold, the pixel is not made to stick. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, an image forming method, and a print medium capable of obtaining a color reproduction image with high saturation while maintaining sharpness, and relates to an electrophotographic color copier, a color printer, a color FAX, etc. The present invention relates to a technique suitable for the image forming apparatus.

  In general, color photographs are required to have superior image quality characteristics such as image gradation, graininess, and color reproducibility compared to text images and line images, and the glossiness of the photograph surface is also improved. It is desirable to have. That is, a mirror-finished photo with a glossy photo or a matte surface called silk is desired.

  Even in electrophotography, there is a method of creating a glossy photograph by forming an image on a light transmission medium and attaching a backing layer to the image carrying surface of the light transmission medium in order to finish the image surface to a mirror surface. It has been proposed (see Patent Documents 1 and 2).

  In the apparatus of Patent Document 1, an image is formed on a light-transmitting substrate, and a backing layer is bonded to the image-bearing surface of the light-transmitting substrate so that the surface of the light-transmitting substrate becomes a photographic surface. A rich photograph is created, and the device of Patent Document 2 forms a color material layer on one of the light transmission medium and the light reflection medium, and the other has an adhesive medium by heating to the other (uniform). A single glossy image is created by adhering and fixing both together.

  As described above, when a sample in which an image is formed on a light transmission medium by electrophotography is handled as a reflection sample, the light transmission medium and the light reflection medium are not optically adhered as in Patent Documents 1 and 2, The inventor has confirmed through experiments and the like that the saturation of the reproduced color is improved when it is not optically adhered.

  The optical adhesion will be described with reference to FIG. FIG. 1A shows a state in which the optical contact is made (hereinafter referred to as optical contact), and FIG. 1B shows a state in which the optical contact is not made (hereinafter referred to as no optical contact). In other words, a sample produced by a normal electrophotographic process corresponds to a sample with “optical contact”, and if there is an air layer between the toner (coloring material) layer and the paper, “no optical contact” Corresponds to the sample.

  In addition, a reflection sample was created with “with / without optical contact” for a sample obtained by forming an image of CMY solid on a light transmission medium by electrophotography, and an example in which saturation was measured and an a * b * plane in FIG. Shown in In FIG. 1C, it can be seen that “no optical contact” improves the saturation.

The reason will be described below.
(1) The intensity of light received per unit area is greater in “without optical contact” than “with optical contact”.

This will be described with reference to FIGS. 2, 3A and 3B. These figures show how light travels until light incident at 45 degrees is received at 0 degrees (however, it does not include the multiple reflection component described later in reason (2) and is the first term in reflectance). Is). 2 shows a state where only an air layer is present on the paper, FIG. 3A shows a state where the paper and the toner layer are in optical contact, and FIG. 3B shows a state where there is no optical contact.
2, 3 (a), and 3 (b), the light is evenly diffused on the paper, and the solid angle Ω includes α light flux. Here, in the case of FIG. 2, the diffused light propagates through the air, so that the α light flux passes through the surface A in the figure.

In the case of optical contact as shown in FIG. 3A, when the diffused light escapes from the toner layer to the air layer, it spreads and propagates in the solid angle Ω1 (> Ω) in the air according to Fresnel law. As a result, the light flux α passes through the surface B that is n ² times larger than the area of the surface A in FIG. Here, n is the refractive index of the toner layer. That is, in the case of FIG. 3A, the light intensity (light density) is reduced as compared with the case of FIG.

  In the case of no optical contact shown in FIG. 3B, when the diffused light escapes from the air layer to the toner layer, it becomes a solid angle Ω2 (<Ω) in the toner layer according to Fresnel law, and propagates narrowly. Next, when the toner layer exits from the air layer, the Fresnel law is again obeyed, so that it propagates back in the solid angle Ω in the air. As a result, the light flux α passes through the surface C having the same size as the area of the surface A in FIG. That is, in the case of FIG. 3B, the light intensity (light density) is the same as that in FIG. 2, so that “without optical contact” is received by the measuring instrument rather than “with optical contact”. The intensity of light per unit area is high and the reflectance is high.

As a result of verification by the present inventor using simple ray tracing, the refractive index of the toner layer is 1.5, and the ratio of “reflectance without optical adhesion” to “reflectance with optical adhesion” is about 2.14.
(2) The greater the ratio of multiple reflected light in the reflected light, the smaller the difference in reflectance between “with and without optical contact”.

This will be described with reference to FIGS. 4 (a) and 4 (b). According to the Williams & Clipper theory, there is inherently multiple reflected light in which light reciprocates between the air layer and the toner layer. 4A shows multiple reflection with “optical contact”, and FIG. 4B shows multiple reflection with “no optical contact”. At this time, 4 to 5% of transmitted light is lost due to Fresnel internal reflection at the interface between the toner layer and the air layer. Even if the number of multiple reflections is the same, the case of “without optical contact” shown in FIG. 4B has a larger number of internal reflections than the case of “with optical contact” shown in FIG. Light decay is fast. As a result, when light having repeated multiple reflections is received, the rate is further reduced. That is, it is considered that the difference in reflectance between “with and without optical contact” decreases as the ratio of the multiple reflected light to the received reflected light increases.
(3) The higher the transmittance of the toner layer, the greater the contribution of the multi-reflection light to the total reflection light.

  This will be described with reference to FIG. FIG. 5A shows the result of calculating the ratio of the first term (without multiple reflections) in the reflectance for each transmittance using the Williams & Clipper theory, where the horizontal axis represents the transmittance and the vertical axis represents the first term. It is the ratio that occupies. In FIG. 5A, the higher the transmittance of the toner layer, the smaller the proportion occupied by the first term. That is, the higher the transmittance of the toner layer, the higher the ratio of the multiple reflected light.

  Assuming this based on the above (1) to (3), the ratio of the “reflectance without optical adhesion” to the “reflectance with optical adhesion” is about twice in the absorption band of the toner layer. As the transmittance increases, it decreases. Here, the absorption band of the toner layer is an absorption band even in the reflection sample, and the transmission band of the toner layer is a reflection band in the reflection sample.

This is illustrated in FIG. 5B. The vertical axis in FIG. 5B is the reflectance, and the data in the figure is the result of “with optical contact, without”. From (1) to (3) described above,
In the state of “with optical contact”,
In C (high reflectivity, that is, the reflection band), since the ratio of the multiple reflected light is large, the change in reflectivity is small even in the “no optical contact” state.
-In the band of B (medium reflectivity), reflectivity is improved when the "no optical contact" state is set.
In A (low reflectance, that is, an absorption band), the ratio of multiple reflected light is small, and therefore the reflectance is about twice as high in the “no optical contact” state. However, since the reflectance is low in the state of “with optical contact”, the difference value of the reflectance is small, and as a result, the change in reflectance can be regarded as small when converted to 0 to 100% which is the reflectance range. That is, it is the band that is neither the absorption band nor the reflection band, that is, the B band, that has a significant change in reflectance when “with or without optical contact”.

  Here, the relationship between the spectral reflectance and the saturation will be explained. In order for the saturation to be high, that is, to increase the a * b * value, the difference in height between the reflection band and the absorption band must be large in the spectral reflectance. . That is, when the state of “with optical contact” is changed to “without optical contact”, the saturation increases because there is little change in the absorption band and the reflectance increases in the reflection band.

  FIG. 6 shows measured data of the spectral reflectance of “with and without optical contact”. In FIG. 6, it can be seen that the effect of cyan toner is particularly great. Therefore, as in the case of cyan in FIG. 6, in the reflection band (about 420 to 570 nm in the case of cyan in FIG. 6), the reflectance is originally not so high, and therefore, the color material with poor chroma reproducibility, The lack of optical contact improves the saturation for the reasons described above. In addition to colors that do not easily exhibit saturation, secondary colors are also effective.

JP 7-72695 A JP 2006-229085 A JP 2006-171607 A

  By the way, when outputting a photographic image by electrophotography, it is necessary to ensure a wide color reproduction range, that is, a wide area gamut in addition to glossiness. However, since a pigment color material is used in electrophotography, it is inferior in transparency as compared with an ink-jet dye color material, and in particular, it is difficult to reproduce high saturation of mixed colors. In addition, in inkjet, it is possible to easily increase the number of ink types in order to achieve wide area gamut while suppressing the total amount restriction, but in order to increase the number of colors in electrophotography, it is not necessary to increase the number of photoconductors. Therefore, the structure becomes complicated and the stability is lowered, which is not realistic. In addition, as described above, it is possible to secure a wide reproduction range without optical contact, but if optical contact is not performed, an image is blurred because an air layer is interposed between the light transmission medium and the light reflection medium. Therefore, sharpness cannot be secured.

The present invention has been made in view of the above problems,
An object of the present invention is to provide an image forming apparatus that forms an image on a light-transmitting medium and bonds the light-transmitting medium and the light-reflecting medium, and has a texture that enables color reproduction images with high saturation while maintaining sharpness. An object of the present invention is to provide an image forming apparatus, an image forming method, and a print medium capable of creating a color print.

  The present invention provides an image forming unit that forms an image on a light transmission medium using image forming toner, an edge extracting unit that extracts an edge amount for each region of the image, and the image according to the extracted edge amount. For each area, an adhesion processing means for setting whether or not the light transmission medium and the light reflection medium are adhered, an adhesion means for adhering adhesive toner to the set adhesion area of the light transmission medium, and The main feature is to have fixing means for aligning and fixing the light reflecting medium so as to contact the surface of the light transmitting medium with the adhesive toner adhered.

  Claims 1, 7, and 8: When a light transmission medium on which an image is formed is adhered to a light reflection medium to produce a printed matter, the light transmission medium and the light reflection medium are adhered using edge information of the image. Since a region is selected, a color print with high color saturation and high sharpness can be created.

  According to the second aspect of the present invention, since the adhesion is set when the edge amount is equal to or larger than the predetermined value, a color print with high color reproduction and high sharpness can be created.

  Claim 3: Since the adhesion area ratio is controlled using the edge amount of the image, it is possible to create a color print with high color reproduction and high sharpness.

  According to the fourth aspect of the present invention, since the adhesive property is changed using the edge amount of the entire input image, a color print suitable for the input image can be created.

  Claims 5 and 6: Since the adhesion dot position is selected using the edge information and the intermediate processing data, it is possible to create a color print capable of color reproduction with high saturation while maintaining sharpness.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 7 shows a configuration example of an image forming system according to the present invention. The image forming system includes a computer 1, an image display device (display) 2, an image processing device 3, an image input device 4, and an image forming device 5.

  The display 2 and the image processing apparatus 3 are directly connected to the computer 1, and the image input apparatus 4 and the image forming apparatus 5 are connected to the computer 1 via a LAN or the like. The computer 1 is loaded with various application software used for data processing related to various information processing and image processing, and software such as a printer driver to which the present invention is applicable. The display 2 is a display device for displaying various output results. The image processing apparatus 3 has a processing function of converting device-specific color signals (RGB, CMY, CMYK, etc.) supplied from the computer 1 into color signals specific to the image forming apparatus 5. In addition, the image processing apparatus 3 includes an adhesion processing unit for setting a region where the adhesive toner is attached to the light transmission medium. The image input device 4 is an input device for capturing image data, and is, for example, a color scanner or a digital camera. The image forming apparatus 5 includes, based on image data (gradation data), an image forming unit that forms a color image on a light transmission medium such as an OHP film or a transparent film, an adhesion unit that adheres adhesive toner, and a sheet that is fixed by fixing. And a fixing unit for performing integration with a light reflecting medium such as the above. The image forming apparatus 5 is not particularly limited as long as it is an apparatus that forms an image by the above-described method such as an electrophotographic method. The number of various input / output devices (image display device, image input device, image forming device, etc.) connected to the computer 1 is not limited to the above number.

  Processing functions of the computer 1 and the image processing apparatus 3 in the image forming system will be described with reference to FIG. The computer 1 performs printing by the image forming apparatus 5 such as various application software 12 that generates the document data 11 and conversion of the document data 11 given from the application software 12 into drawing commands that can be processed by the image processing apparatus 3. A printer driver 13 that performs processing necessary for this, and a disk (storage means) 14 for storing drawing commands from the printer driver 13 are provided.

  The image processing apparatus 3 includes a color conversion processing unit 31 that performs color conversion processing on RGB format color data of a drawing command that is transmitted to and received from the computer 1, and converts the command format image data into raster format image data. A rendering processing unit 32 for conversion, a band buffer 33 for storing raster format image data, and a page memory 34 for storing raster format image data stored in the band buffer 33, and a drawing sent from the computer 1 It has a function of converting the command into print data that can be processed by the image forming apparatus 5. The color conversion processing unit 31 is provided with an adhesion processing unit that selectively sets an area to which adhesive toner is attached using color information such as CMY.

  The operation of this image processing system will be described. As one of the operations of the image processing system, the image data is output to the image processing apparatus in order to output (print) the image by the image forming apparatus 5 capable of forming a color image while displaying the image data in the computer 1 on the display 2. 3, receiving the processing result from the image processing apparatus 3 and transferring it to the image forming apparatus 5. In this case, the image data is a color signal composed of R (red), G (green), and B (blue) color components, which are color components for display on a general color display.

  Therefore, the computer 1 sends out the RGB signals to the image processing device 3, and the image processing device 3 outputs color signals C (cyan) and M (magenta) composed of output color components which are control signals in the image forming device 5. ), Y (yellow), and K (black) signals. At the same time, the image processing apparatus 3 transfers the bonding data in which the area to which the adhesive toner is attached is set to the image forming apparatus 5. As a result, the image forming apparatus 5 forms a color image and an image to which adhesive toner is attached, and outputs the print medium after fixing.

  The operation from when the computer 1 generates a drawing command to be sent to the image processing apparatus 3 to when the image processing apparatus 3 performs image processing and outputs image data to the image forming apparatus 5 will be described.

  When the computer 1 is operated by the user, editing is performed while displaying the image data on the display 2 using the application software 12 of the computer 1 or the like. When the editing operation is completed, the image forming apparatus 5 to be output is designated and printing is selected on the application software 12. When printing is selected by the application software 12 and printing is instructed by the print property, the computer 1 passes the image data selected by the application software 12 to the printer driver 13, and the printer driver 13 performs image processing on the document data 11. The drawing command is converted into a receivable command that can be received by the apparatus 3 and is sequentially stored on the disk 14.

  On the other hand, upon receiving a print instruction from the computer 1, the image processing apparatus 3 sequentially reads the drawing commands that the printer driver 13 saves on the disk 14 and transfers the color data of the drawing commands to the color conversion processing unit 31. The color conversion processing unit 31 performs predetermined color conversion processing and adhesion processing on the RGB format color data to convert it into data in a format suitable for the image forming apparatus 5 such as a color printer. The rendering processing unit 32 converts the image data into raster format image data and stores it in the band buffer 33, and further stores the raster format image data stored in the band buffer 33 in the page buffer 34.

  The gradation data stored in the page buffer 34 of the image processing apparatus 3 is read by the computer 1 and transferred to the designated image forming apparatus 5, so that the image forming apparatus 5 forms and outputs an image on a recording medium. .

  In the above description, the image processing device 3 performs color conversion processing, adhesion processing, rendering processing, gradation processing, and the like. These processing functions are performed as software (programs) in a computer as an information processing device. Alternatively, it can be mounted as a dedicated processing apparatus such as an ASIC, or can be mounted in the same manner in the control unit on the image forming apparatus side, and is independent of an image forming apparatus such as a dedicated print server. It can also be performed by a control device.

  FIG. 9 shows a configuration example of the image forming apparatus of the present invention. The image forming apparatus 5 includes an image forming unit that forms an image on the light transmissive medium with color toner for image formation, an attachment portion that adheres adhesive toner to the light transmissive medium, and a first that fixes the light transmissive medium. The fixing unit includes an alignment unit that aligns the fixed light transmission medium and the light reflection medium, and a second fixing unit that closely contacts and joins the aligned light transmission medium and the light reflection medium.

  In the image forming apparatus shown in FIG. 9A, the image forming unit generates four image forming units that form toner images of different colors, that is, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image, respectively. The image forming units Y, M, C, and K to be formed are formed, and the adhesive toner attaching portion is formed of an image forming unit S for adhesive toner. These image forming units Y, M, C, K, and S have almost the same configuration and operation of the electrophotographic process except that the toner is different. The toner used in the present invention is a toner manufactured by the manufacturing method described in Patent Document 3, and the proper fixing temperature of the image forming toner is 160 to 190 ° C. for each color. The proper fixing temperature of the adhesive toner is 110 to 190 ° C.

  The operation of the image forming apparatus of the present invention will be described. In each of the image forming units Y, M, C, K, and S, 41 is a drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive member) as an image carrier. It is rotationally driven in the direction of the arrow (counterclockwise) by a drive unit (not shown). A charging unit 42 uniformly charges the surface of the photoconductor 41 to a predetermined polarity and potential. Reference numeral 43 denotes an exposure unit, which is disposed on the downstream side of the charging unit 42 in the rotation direction of the photoconductor 41.

  In each of the units Y, M, C, and K in the image forming unit, the surface of the photosensitive member 41 uniformly charged by the charging unit 42 is optically scanned based on the drawing data sent from the image processing device 3, and the photosensitive member 41 is scanned. An electrostatic latent image is formed thereon. Further, in the image forming unit S which is an adhesive toner attaching portion, the surface of the photosensitive member 41 uniformly charged by the charging unit 42 is optically scanned based on the bonding data sent from the image processing apparatus 3, and the photosensitive member 41. An electrostatic latent image is formed thereon. As the exposure means, a laser scanner, an LED array, or the like can be used. A developing unit 44 is disposed downstream of the exposure unit 43 in the rotation direction of the photoconductor 41 and develops the electrostatic latent image on the photoconductor 41 with toner. Reference numeral 45 denotes a primary transfer portion, which is disposed at a primary transfer position T1 at a position facing the photoreceptor 41 with the intermediate transfer belt 47 interposed therebetween, and the photoreceptor 41 is placed on the intermediate transfer belt 47 by the transfer electric field of the primary transfer portion 45. The upper toner image is primarily transferred. A photoconductor cleaning unit 46 removes untransferred toner that has not been transferred to the intermediate transfer belt 47 by the transfer unit 445 from the surface of the photoconductor 41. The above-described operation is performed in the five image forming units Y, M, C, K, and S, and the yellow toner image formed by the image forming unit Y and the magenta formed by the image forming unit M are formed on the intermediate transfer belt 47. The toner image, the cyan toner image formed by the image forming unit C, the black toner image formed by the image forming unit K, and the adhesive toner image formed by the image forming unit S are transferred to the primary transfer portion T1 of each image forming unit. Superimposed in sequence and primary transferred. As a result, an unfixed full color toner image formed by superimposing the respective images of yellow toner, magenta toner, cyan toner and black toner is synthesized and formed on the intermediate transfer belt 47, and an adhesive toner image is formed.

  An intermediate transfer belt 47, which is an intermediate transfer body, is suspended by a driving roller 48 and driven rollers 49, 50, and contacts the photoreceptor 41 of each image forming unit Y, M, C, K, S and rotates in the direction of the arrow. Is driving. A secondary transfer unit 51 is disposed at a secondary transfer position T2 at a position facing the driven roller 49 with the intermediate transfer belt 47 in the middle. Due to the transfer electric field of the secondary transfer unit 51, the toner on the intermediate transfer belt 47 is transferred to the light transmission medium P introduced at the secondary transfer position T2 in synchronization with the toner image on the intermediate transfer belt 47 from a paper supply unit (not shown). Secondary transfer of the image.

  A color toner image corresponding to the color image of the document is formed in a mirror image state on the light transmission medium, and an adhesive toner image is further formed thereon. An intermediate transfer belt cleaning unit 52 removes transfer residual toner that is not transferred to the transfer material on the intermediate transfer belt. Reference numeral 60 denotes a first fixing unit which heats and pressurizes the toner image on the transfer material to fix it on the transfer material. A heater is disposed inside the fixing roller 61 to control the temperature. Reference numeral 62 denotes a pressure roller.

  Although the toner for adhesion gives the property of softening at a lower temperature than the image forming toner, according to the technology of Patent Document 3 described above, the fixing roller offset property at a high temperature is equivalent to that of the image forming toner. The toner can be fixed at the same fixing roller temperature as the toner for use. In the present invention, the fixing temperature in the first fixing unit is set to 180 ° C.

  In FIG. 9B, reference numeral 70 denotes an alignment unit, which is sent from the first fixing unit 60 in FIG. 9A, forms a color image, and the fixed light transmission medium P is sent to the alignment unit 70. . Alignment is performed so that the light reflection medium Q is brought into contact with the surface on which the adhesion portion is formed by the adhesive toner with respect to the light reflection medium Q introduced into the alignment position T3 in synchronization with the light transmission medium P from a paper supply unit (not shown). . Reference numeral 80 denotes a second fixing unit, which heats and pressurizes the light transmission medium P and the light reflection medium Q aligned by the alignment unit, and bonds the bonding unit to which the adhesive toner is adhered. The function required for the second fixing unit is the same as that of the fixing unit of the image forming apparatus. In the present invention, the first fixing unit is used. The two media are transported to the second fixing unit 80 and are heated so that only the adhesive toner exhibits adhesiveness, and is pressed to be joined. A heater is disposed inside the fixing roller 81 to control the temperature. 82 is a pressure roller. Since the optimum temperature for bonding varies depending on the required adhesive force and the heat capacity of paper, the temperature of the fixing roller can be changed by the main body control unit. In this invention, it set to 125 degreeC. Finally, the medium on which the color toner image and the adhesive toner image are fixed is carried out as a print medium to a paper discharge tray (not shown).

  In the above example, a color image is formed on the light transmissive medium by the image forming unit, an adhesive toner image is formed on the light transmissive medium by the adhesive toner attaching portion, and the light transmissive medium is fixed by the first fixing unit. In the second fixing unit, the light transmission medium and the light reflection medium conveyed from the paper tray are aligned and joined. For example, the image forming unit forms only a color image on the light transmission medium. The adhesive toner image may be fixed and formed on the light reflecting medium, and the adhesive toner image may be bonded to the light reflecting medium.

Example 1
In the first embodiment, edge extraction is performed on each pixel of input image data, and whether or not the light transmission medium and the light reflection medium are bonded is determined for each pixel using the result.

  FIG. 10 illustrates a configuration of the color conversion processing unit according to the first embodiment. In FIG. 10, the color conversion processing unit 31 uses a printer driver 13 of the computer 1 to set a color conversion parameter setting unit 307 for setting color conversion parameters, a black processing parameter setting unit 308 for setting black processing parameters, and a γ conversion parameter. Γ conversion parameter setting unit 309 for setting the total amount control parameter setting unit 310 for setting the total amount control parameter, halftone processing parameter setting unit 311 for setting the halftone processing parameter, and the adhesion processing parameter for setting the adhesion processing parameter A setting unit 312 and an edge extraction parameter setting unit 313 for setting edge extraction parameters are provided.

  In addition, the color conversion processing unit 31 uses the color conversion parameters set by the color conversion parameter setting unit 307 to generate and output CMYK signals from the RGB image signals for each pixel. A color space conversion unit 301 that converts a color signal (RGB format signal) into a print color signal (CMY signal), and a black processing unit that converts a CMY signal component into a CMYK signal with a K component added according to the UCR and CUA rates. 302, a γ correction unit 303 that generates and outputs a C′M′Y′K ′ signal by correcting γ corresponding to the image forming engine characteristic with respect to the CMYK signal, and a C′M′Y′K ′ signal. The total amount regulating unit 304 that generates and outputs the C "M" Y "K" signal according to the maximum total amount value of the recording color materials that the image forming apparatus 5 can form an image on, and the dither for the C "M" Y "K" signal. Processing etc. A halftone processing unit 305 that performs halftone processing (gradation processing) and converts it into gradation data (print data) that can be processed by the image forming apparatus 5 is provided.

  In addition, the color conversion processing unit 31 includes an adhesion processing unit 306 for performing edge determination based on RGB signals, determining pixels to which adhesion toner is attached, and transmitting adhesion data to the image forming apparatus 5. .

  Next, an example of the bonding process will be described in detail. As described with reference to FIGS. 1 to 6, the reproducibility of the saturation is improved when the light transmission medium and the light reflection medium are not optically contacted, but the sharpness is reduced unless the optical contact is performed. Adhere optically. Specifically, the edge amount of the image is extracted, and when the edge amount is a predetermined value or more, the light transmission medium and the light reflection medium are bonded.

  FIG. 11A shows a configuration example of the adhesion processing section of the first embodiment. The adhesion processing unit 306 determines whether or not to adhere each pixel based on the edge amount of the pixel. As illustrated in FIG. 11A, the adhesion processing unit 306 includes an edge extraction unit 401, an adhesion region determination unit 402, and a resolution conversion unit 403.

The edge extraction unit 401 calculates a luminance value from the RGB data, calculates an edge amount, and transmits the result to the adhesion region determination unit 402. The luminance value is calculated using the following formula.
Y = 0.299 * R + 0.587 * G + 0.114 * B Formula (1)
The edge extraction filter is a 3 × 3 or 5 × 5 filter as shown in FIGS. 12A and 12B, and is a differential filter in which the sum of the filter coefficients is “0”. There are surrounding pixels for the pixel of interest in the center of the filter. In the filter processing, normally, a positive value and a negative value are regarded as equivalent difference values, and an absolute value is output as an edge amount. The edge detection direction and the edge extraction amount vary depending on the filter coefficient of the edge extraction filter.

  An edge extraction filter is set in the edge extraction parameter setting unit 313. In this embodiment, a fixed filter as shown in FIGS. 12A and 12B is used regardless of the type of input image, but the vertical line extraction filter shown in FIG. The vertical line and horizontal line portions may be individually extracted with the horizontal line extraction filter shown. In this embodiment, the filtering process is performed on the luminance value. However, in order to simplify the processing, a signal other than the luminance value such as a G signal may be used.

  The adhesion region determination unit 402 calls the adhesion processing parameter 312 and determines, for each pixel, whether or not to adhere based on the edge amount extracted by the edge extraction unit 401. Binary (adhesive / non-adhesive) image data is created as data output from the adhesion region determination unit 402. The resolution conversion unit 403 converts the image data obtained by the adhesion area determination unit 402 into the resolution of the image forming apparatus 5, and transmits the converted data to the image forming apparatus 5.

  The adhesion processing parameter 312 is a rectangular function having an edge amount as an input value. FIG. 11B shows an example of adhesion processing parameters when the input value is an edge amount. Here, the edge amount is an output value of the edge extraction unit 401, and the larger the value, the higher the sharpness. When an edge amount is input to the rectangle function, a determination result that the image does not adhere is returned when the value is less than a predetermined value (edge amount <X), and a determination result that the image is bonded when the value is equal to or greater than the predetermined value (X ≦ edge amount). return. Alternatively, a rectangular function having an input value with a value of 1 for bonding and a value of 0 for non-bonding may be set for the edge amount. In the bonding processing parameter 312, a determination table or threshold determination using the edge amount as an input may be performed. It may be defined.

Example 2
In the second embodiment, edge extraction is performed on each pixel of input image data, an adhesive area ratio for adhering adhesive toner is determined using the edge amount, and N-value (N ≧ 3) image data after halftone processing This is an embodiment in which the dot position to which the adhesive toner is attached is selected and determined based on the above.

  FIG. 13 illustrates the configuration of the color conversion processing unit of the second embodiment. In FIG. 13, the color conversion processing unit 31 includes a color conversion parameter setting unit 507, a black processing parameter setting unit 508, a γ conversion parameter setting unit 509, a total amount restriction parameter setting unit 510, and a halftone processing parameter setting unit 511. And an adhesion processing parameter setting unit 512 for setting an adhesion processing parameter, and an edge extraction parameter setting unit 513 for setting an edge extraction parameter.

  Further, the color conversion processing unit 31 includes a color space conversion unit 501, a black processing unit 502, a γ correction unit 503, a total amount regulation unit 504, a halftone processing unit 505, and N-value data after halftone processing. And an adhesion processing unit 506 for determining a dot position where the adhesion toner is hit based on the edge amount of the pixel.

  FIG. 14A shows the configuration of the adhesion processing unit 506. The adhesion processing unit 506 includes an edge extraction unit 601, an adhesion area ratio determination unit 602, a resolution conversion unit 603, and an adhesion dot determination unit 604. The edge extraction unit 601 calculates a luminance value from RGB data input for each pixel, and calculates an edge amount. The adhesion area ratio determining unit 602 obtains area ratio data for adhesion from the edge amount. The resolution conversion unit 603 converts the input image data into the resolution of the image forming apparatus 5. The adhesive dot determination unit 604 receives the area ratio of each pixel of the input image data and the N-value print data from the halftone processing unit 505, determines adhesive dots for the resolution-converted image data, and uses the adhesion data. To the image forming apparatus 5.

  Next, the process in the adhesion area ratio determination unit 602 will be described. The adhesion area ratio determination unit 602 receives the edge amount calculated by the edge extraction unit 601 and obtains area ratio data for bonding. FIG. 14B shows a function f (x) for determining the adhesion area ratio, which determines the adhesion area ratio with respect to the input edge amount. The adhesion area ratio of 1 is whole surface adhesion, and TH is the minimum area ratio for integrating the light transmission medium and the light reflection medium. Through the above processing, the adhesion area ratio corresponding to the edge amount of each pixel is determined.

  As an example of the adhesion processing parameter 312, a conversion table of the function f (x) shown in FIG. 14B is held. The bonding area ratio is set so that continuity is maintained with respect to the size of the edge amount.

  Next, processing in the halftone processing unit 505 will be described. Since the halftone processing unit 505 converts multi-value (M value> N value) data into N-value data, for example, dots are generated in the low density portion of the image as shown in FIG. In the middle density portion, dots are generated as shown in FIG. 15B, and in the high density portion of the image, dots are generated as shown in FIG. 15C. In FIGS. 15A to 15C, each pixel has 16 gradations (four values) (the black circle in the figure indicates that one dot has been shot (dot on)).

Next, the process in the adhesion dot determination part 604 is demonstrated. Using the edge information, a dot position where adhesive toner is applied (attached) is determined for each input pixel according to the following rules.
(1) When the input pixel is an edge pixel, importance is attached to sharpness. In order to emphasize the edge, when the target pixel has a high density, an adhesive toner is applied so that the high density portion is adhered. Conversely, when the target pixel has a low density, the adhesive toner is applied so that the low density portion is adhered. That is, it is only necessary to attach the adhesive toner preferentially from the dot with the higher area ratio by looking at the area ratio of the dots with or without color toner.
(2) When the input pixel is not an edge pixel, priority is given to color reproducibility. Regarding how to apply adhesive toner with emphasis on color reproduction, the dot position where the adhesive toner is applied is determined for each pixel according to the following rules.
(2.1) In the vicinity of the maximum saturation point (point HP in FIG. 16), it is better not to optically contact the light transmission medium and the light reflection medium in order to improve the saturation. (Dot-off position) is selected, and adhesive toner is applied to the selected dot-off position.
(2.2) In the vicinity of the white point (point WP in FIG. 16), it is better not to optically contact the light transmitting medium and the light reflecting medium. Therefore, select a dot (dot-on position) where color toner is applied, Adhesive toner is applied to the selected dot-on position.
(2.3) When three or more color toners are applied in the shadow portion, it is preferable that the adhesive toner overlaps the dot positions. This is because by performing optical contact, the saturation of the dots up to the secondary color is lowered, but the brightness is lowered only when three or more colors are overlapped. The same applies when black toner is applied. Here, the color of three or more colors is limited to the case where the spectral characteristics are almost flat when they overlap.
(2.4) For the color gamut other than (2.1) to (2.3), the dot position where the adhesive toner is applied may be arbitrarily selected. In other words, inside the gamut, color adjustment can be performed by the color conversion table regardless of whether there is optical contact or not. Therefore, the dot position where the adhesive toner is applied may be arbitrarily selected.

  In other words, if the target pixel has a high density, the adhesive toner is preferentially hit from the dot where the color toner is not hit, and if the target pixel is a low density, the adhesive toner is hit from the dot where the color toner is hit. Good.

  Here, the adhesion area ratio is assumed to be f (x) = R. In the case of reproduction of 16 dots per pixel (16 gradations) shown in FIGS. 15A to 15C, the adhesion area ratio is controlled in units of 1/16, and rounding is performed when performing numerical calculation. When the input pixel is determined to have a high density at the edge, according to the above rule, adhesion of the adhesive toner preferentially selects a dot position where the color toner is applied. First, the dot position where the color toner is applied is selected, and after selecting all the dot positions where the color toner is applied, the dot position where the color toner is not applied is selected. Adhesion of the adhesive toner is terminated when the number of dots to which the adhesive toner is applied exceeds R, which is a predetermined adhesion area ratio, with respect to the number of dots constituting one pixel.

  FIG. 17 is a process flowchart of the adhesive dot determination unit 604. If the edge amount of the target pixel of the input data is equal to or larger than the threshold value (S700) and the number of dots to which color toner is applied is larger (ie, high density) (S701), first, the dot position at which the color toner is applied is set. Adhesive toner is struck (S702), and if the adhesive area ratio where the adhesive toner is struck at this point does not reach the specified value (S703), the color toner is applied until the adhesive area ratio reaches the specified value. Adhesive toner is applied to a dot position that does not exist (S704).

  If the edge amount of the target pixel of the input data is equal to or larger than the threshold value (S700) and the number of dots to which color toner is applied is smaller (that is, low density) (S701), first, the dot that is not applied with color toner. Adhesive toner is applied to the position (S705). If the adhesion area ratio does not reach the specified value at this point (S706), the dot position where the color toner is applied until the adhesion area ratio reaches the specified value. Adhesive toner is applied to the surface (S707).

  On the other hand, if the edge amount of the target pixel of the input data is not equal to or greater than the threshold value (S700) and the number of dots to which color toner is applied is larger (ie, high density) (S708), the color toner is not applied first. Adhesive toner is applied to the dot position (S709), and if the adhesive area ratio at which the adhesive toner is applied does not reach the specified value (S710), the color toner is used until the adhesive area ratio reaches the specified value. Adhesive toner is applied to the dot position where the toner is applied (S711).

  Further, when the edge amount of the target pixel of the input data is not equal to or larger than the threshold value (S700) and the number of dots to which color toner is applied is smaller (that is, low density) (S708), the color toner is applied first. Adhesive toner is applied to the dot position (S712), and if the adhesive area ratio at which the adhesive toner is applied does not reach the specified value (S713), the color toner is used until the adhesive area ratio reaches the specified value. Adhesive toner is applied to the dot positions where the toner is not applied (S714).

  As described above, in this embodiment, the adhesion area ratio of the adhesion toner adhesion region can be determined according to the edge amount of each pixel of the input image. In this embodiment, the dot to which the adhesive toner is attached can be selected according to the adhesion area ratio and the edge amount. Further, f (x) shown in FIG. 14B is a nonlinear function, but may be a linear function. However, it must be a monotonically increasing function with respect to the increase in edge amount.

Example 3
Example 3 is an example in which the adhesion parameter (adhesion area ratio) is changed according to the edge degree of the entire input image data.

  For example, when the input image data is an image having a low edge degree as a whole, that is, as shown in FIG. 14B, if a fixed adhesion parameter is always used, depending on the input image, The adhesive strength with the light reflecting medium is deteriorated, and the sense of unity is lost. Therefore, in the third embodiment, the adhesion parameter is changed according to the overall edge degree of the input image data.

FIG. 18 illustrates a configuration of a color conversion processing unit according to the third embodiment. In FIG. 18, a bonding process parameter setting unit 812 that sets a bonding process parameter receives input image data and rewrites the bonding parameter. FIG. 19A shows the configuration of the adhesion processing parameter setting unit. When receiving the RGB data, the edge degree calculation unit 900 calculates the edge degree of the entire input image data.
For example, (edge degree) = (sum of edge amounts of each pixel) / (number of pixels) is calculated. Here, the average is taken for the number of used pixels. Using the calculated edge degree, the f (x) rewriting unit 901 rewrites the function f (x) that is an adhesion parameter. For example, as shown in FIG. 19B, the TH in FIG. 14B is rewritten with respect to the edge degree of the entire image data on the horizontal axis.

  The higher the degree of edge of the whole image, the lower the TH that is the adhesion area ratio (set the minimum value of the adhesion area ratio to a low value), so that the adhesion area ratio is optimally corrected for any input image. Is possible. Further, the adhesion processing unit 806 performs an adhesion process using the rewritten adhesion parameter. This adhesion process is the same as the process of Examples 1 and 2 described above.

The refractive index of the material used for the adhesive toner described above should be equal to or lower than the refractive index of the color toner. This is because the reproduction color changes depending on the presence / absence of optical adhesion due to the change in the traveling direction of the light reflected from the paper. The color toner composition is as follows:
・ Polyester resin 100 parts by weight (refractive index 1.63)
・ 6 parts by weight of paraffin wax (refractive index 1.40)
Silica 1.5 parts by weight (refractive index 1.46)
It is.

  In the case of a color toner, 3 to 6 parts by weight of a pigment that determines the color of the toner is contained in addition to the above. Depending on the pigment, the refractive index varies, but if the refractive index of the pigment is significantly different from the refractive index of the resin that serves as the binder, light scattering occurs between the pigment and the binder, resulting in a decrease in transparency as a toner and a color reproduction range. Therefore, the refractive index of the pigment used for the toner is generally selected to be equivalent to the refractive index of the resin.

The composition of the adhesive toner is
・ Polyester resin 100 parts by weight (refractive index 1.63)
・ 12 parts by weight of paraffin wax (refractive index 1.40)
・ Silica 5 parts by weight (refractive index 1.46)
It is.

  The number of parts of the polyester resin with the highest refractive index remains the same, and the number of parts by weight of paraffin wax and silica increases, but the refractive index of both is close to that of the polyester and the number of parts by weight is small. There is almost no effect. Also, as in the case of pigment selection, mixing a composition material having a refractive index that is significantly different from the refractive index of the polyester resin, which is the main raw material, causes light scattering between them, resulting in loss of transparency as a toner. Such a composition cannot be used. Therefore, the refractive index of the adhesive toner is equivalent to that of the color toner.

  As described above, according to the present invention, an adhesive region is selected in accordance with edge information with respect to an image-formed light transmission medium, adhesive toner is attached to the adhesive region, and the light reflection medium is fixed. Therefore, an image with high saturation and sharpness can be output. In the above embodiment, the number of toner colors used for image formation is four, but the number of colors is not limited to four, and any number of colors may be used. In the above embodiment, the electrophotography is described as an example, but the present invention can be applied to an ink jet printer that can print on a light transmission medium. Also, the image signal input to the adhesion processing apparatus is an RGB signal, and the adhesion area ratio and the like are determined. For example, the adhesion area is based on the CMY signal which is a complementary color and the C "M" Y "K" signal after the total amount is regulated The rate can also be determined.

It is a figure explaining the difference in the reproduction color in the case where it is optically closely_contact | adhered, and the case where it is not optically closely_contact | adhered. It is a figure explaining the light reception amount in the state of only an air layer. It is a figure explaining the light reception amount in the state which is optically contacted, and the state which is not optically contacted. It is a figure explaining the multiple reflection in the state which is optically closely_contact | adhered, and the state which is not optically closely_contact | adhered. It is a figure explaining the relationship between the transmittance | permeability and multiple reflection. The spectral reflectance when optically in close contact and when not optically in close contact is shown. 1 shows a configuration example of an image forming system according to the present invention. 1 shows a processing configuration of a computer and an image processing apparatus in an image forming system. 1 shows a configuration of an image forming apparatus of the present invention. 1 illustrates a configuration of a color conversion processing unit according to a first exemplary embodiment. The structural example of the adhesion process part of Example 1 is shown. An example of an edge extraction filter is shown. 2 shows a configuration of a color conversion processing unit according to a second embodiment. The structure of the adhesion processing part of Example 2 is shown. An example of a gradation image is shown. FIG. 10 is a diagram for explaining selection of a dot position where adhesive toner is applied when importance is attached to color reproduction. 10 is a process flowchart of an adhesive dot determination unit according to the second embodiment. 10 shows a configuration of a color conversion processing unit according to a third embodiment. The structure of the adhesion process parameter setting part of Example 3 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 301 Color space conversion part 302 Black processing part 303 Gamma correction part 304 Total amount control part 305 Halftone processing part 306 Adhesion processing part 307 Color conversion parameter setting part 308 Black process parameter setting part 309 Gamma conversion parameter setting part 310 Total quantity control parameter setting part 311 Halftone processing parameter setting unit 312 Adhesion processing parameter setting unit 313 Edge extraction parameter setting unit

Claims (8)

  Image forming means for forming an image on a light transmission medium using image forming toner, edge extracting means for extracting an edge amount for each area of the image, and for each area of the image according to the extracted edge amount An adhesion processing means for setting whether or not the light transmission medium and the light reflection medium are adhered; an adhesion means for adhering adhesive toner to the set adhesion area of the light transmission medium; and the light transmission medium. An image forming apparatus comprising: a fixing unit that aligns and fixes the light reflecting medium so as to contact a surface to which the adhesive toner is attached.   The image forming apparatus according to claim 1, wherein the adhesion processing unit sets the area of the image as an area to be adhered when the extracted edge amount is a predetermined value or more.   The adhesion processing means sets an adhesion area ratio for adhering adhesive toner according to the extracted edge amount, and sets the continuity of the adhesion area ratio with respect to the edge amount. The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 3, further comprising an edge degree calculating unit that calculates an edge degree of the entire image, and changing the adhesion area ratio according to the calculated edge degree.   The image forming apparatus according to claim 1, wherein the adhesion processing unit sets a dot position to which the adhesion toner is attached according to the extracted edge amount.   When the edge amount is equal to or greater than a predetermined value, the adhesion processing unit compares the area ratio of the dot to which image forming toner is adhered and the dot to which the image formation toner is not adhered, and adheres the adhesive toner to the dot position having the higher area ratio. The image forming apparatus according to claim 5, wherein the image forming apparatus is set as a dot position.   An image forming step of forming an image on a light transmission medium using image forming toner, an edge extraction step of extracting an edge amount for each region of the image, and for each region of the image according to the extracted edge amount An adhesion processing step for setting whether or not the light transmission medium and the light reflection medium are bonded; an adhesion step for attaching an adhesive toner to the set adhesion region of the light transmission medium; and the light transmission medium. An image forming method comprising: a fixing step of aligning and fixing the light reflecting medium in contact with the surface to which the adhesive toner is adhered.   A print medium produced by the image forming method according to claim 7.

Images