Image processing device, image reading device, image forming device, and image processing method

Abstract

To provide an image processing apparatus, an image reading device, an image forming apparatus, and an image processing method that can appropriately correct a deteriorated image.SOLUTION: When an image processing apparatus receives an instruction to perform processing that requires reading of a document such as scanning, copying, and facsimile transmission (S401: YES), the image processing apparatus reads both sides of a document (S402), detects the background colors of the front and back of the document (S403), when the front and back of the document have different background colors (S404: YES), a character part does not have a uniform pixel value (S405: NO), and the character part has high R intensity (S407: YES), can determine that the sheet type of the document is thermal paper and an image is deteriorated, and thus executes image correction processing (S408) to create an image close to an image before the deterioration from the image after the deterioration.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an image processing device, an image reading device, an image forming device, and an image processing method, and more particularly to an image processing technique for correcting an image according to its degradation state. [Background technology]

[0002] In recent years, various medical images have been used for diagnosis in the medical field because they are visually very easy to understand. Among medical images, ultrasound images, unlike X-ray images, pose less risk of radiation exposure during imaging, require less expensive and smaller imaging devices than MRI images, and allow real-time diagnosis, so they are used for diagnosis in a wide range of fields.

[0003] If a medical image is not clear, it can be difficult to make an accurate diagnosis, and ultrasound images are no exception to the need for sharpening. For this reason, for example, a technique has been proposed for removing noise components of specific frequencies present in multiple frame images (see, for example, Patent Document 1). By adopting such a technique, ultrasound images can be sharpened. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-055415 Summary of the Invention [Problem to be solved by the invention]

[0005] However, medical images such as ultrasound images have uses other than diagnostics.

[0006] For example, ultrasound images (echo images) taken during prenatal checkups are printed and provided as precious keepsakes for both the pregnant woman and her family. Clear ultrasound images are especially appreciated.

[0007] Such ultrasound images are generally printed on thermal paper, but because thermal paper has low durability, there is a risk that the printed image will deteriorate to the point where it becomes unrecognizable within as little as a few years.

[0008] To prevent the loss of precious ultrasound images, it is possible to take pictures in advance using a smartphone or digital camera, or to copy or scan them, but during pregnancy or immediately after giving birth, women are often busy or in poor health and do not have the time to take such measures.

[0009] This problem of deterioration of printed images is not limited to medical images and exists in a wide range of fields.

[0010] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an image processing device, an image reading device, an image forming device, and an image processing method that can appropriately correct degraded images. [Means for solving the problem]

[0011] In order to achieve the above object, an image processing apparatus according to an embodiment of the present disclosure includes: A picture an image processing device for processing an image, comprising: a specifying means for specifying the sheet type of the document; A determination means for determining whether or not image deterioration specific to the specified sheet type has occurred based on the image read from the document, and when the determination means determines that image deterioration has occurred, the deterioration and a correction means for executing image processing to correct the degraded image.

[0012] In this case, the correcting means may correct the deteriorated image so that the deteriorated image approaches the image before deterioration.

[0013] The correction means may correct at least one of a background color and a character portion in the degraded image.

[0014] The identifying unit may identify the sheet type of the document by using the degraded image.

[0015] In this case, the specifying means is a predetermined sheet type. Which types of Unique features Image degradation due to before Recorded picture image occurring in It is desirable to specify the sheet type of the document depending on the type of the document.

[0016] For example, the specifying unit may specify whether the sheet type of the document is thermal paper.

[0017] The identifying unit may identify the sheet type of the document as thermal paper when the background color of the degraded image differs from that of an image obtained by scanning the back side of the degraded image of the document.

[0018] The identifying unit may identify the sheet type of the document as thermal paper when the density of the character portion in the degraded image is not uniform.

[0019] The identifying unit may identify the sheet type of the document as thermal paper when a character portion in the degraded image is reddish.

[0020] Furthermore, when the sheet type of the document is thermal paper, the correction means may execute image processing to match the background color of the degraded image with the background color of an image obtained by reading the back side of the degraded image of the document.

[0021] Furthermore, the correction means may execute image processing to enhance the contrast of the degraded image when the type of the document sheet is thermal paper.

[0022] Furthermore, the correction means may execute image processing to enhance the sharpness of the degraded image when the type of the document sheet is thermal paper.

[0023] Furthermore, when the sheet type of the document is thermal paper, the correction means may execute image processing to reduce redness of printed portions in the degraded image.

[0024] In addition, the image reading device according to an embodiment of the present disclosure is Ra-ga reading means for reading the image; The reading means processes the image read from the document. an image processing device according to an embodiment of the present disclosure; R It is characterized by:

[0025] In addition, an image forming apparatus according to one embodiment of the present disclosure is characterized by comprising an image processing apparatus according to one embodiment of the present disclosure and an image forming means for forming an image using a processed image obtained by image processing of the image processing apparatus.

[0026] In addition, an image forming apparatus according to another embodiment of the present disclosure is characterized by comprising an image reading apparatus according to one embodiment of the present disclosure and an image forming means for forming an image using a processed image obtained by image processing of the image processing apparatus.

[0027] In this case, the device may include a color mode discrimination means that determines that the processed image is a full-color image if the average saturation of the printed portion of the processed image is equal to or greater than a predetermined threshold, and determines that the processed image is a monochrome image if the average saturation is less than the predetermined threshold, and the color mode discrimination means changes the predetermined threshold so that the processed image is determined to be a monochrome image when the sheet type of the original is thermal paper, and the image forming means forms the processed image according to the discrimination result of the color mode discrimination means.

[0028] Furthermore, when the sheet type of the original is thermal paper, it is desirable that the image forming means form the processed image as a monochrome image, and it is even more desirable that the image forming means maximize the shading setting when forming the processed image as a monochrome image.

[0029] In addition, the image processing method according to an embodiment of the present disclosure is A picture An image processing method for processing an image, comprising: a specifying step of specifying a sheet type of the document; a determining step of determining whether or not image deterioration specific to the specified sheet type has occurred based on the image read from the document; and if it is determined that image deterioration has occurred in the determining step, the determining step of determining whether or not the image deterioration has occurred. and a correction step of executing image processing to correct the degraded image. [Effects of the Invention]

[0030] In this way, by focusing on the fact that the deterioration state of an image differs depending on the type of document sheet, correction processing of the deteriorated image is performed according to the type of document sheet, so that an image close to the original image can be obtained from the deteriorated image. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is an external perspective view showing a main configuration of an image forming apparatus 1 according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing the main configuration of an image reading unit 120 and an automatic document transport unit 121. [Figure 3] FIG. 2 is a block diagram showing the main components of a control unit 101. [Figure 4] 10 is a flowchart showing a main routine of a process for correcting a degraded image read from a thermal paper document. [Figure 5] 10 is a flowchart showing image correction processing (S408). [Figure 6] (a) is a diagram illustrating the front and back of thermal paper before the image deteriorates over time, and (b) is a diagram illustrating the front and back of thermal paper after the image deteriorates over time. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments of an image processing device, an image reading device, an image forming device, and an image processing method according to the present disclosure will be described with reference to the drawings. [1] Configuration of image forming device First, the configuration of the image forming apparatus according to the present embodiment will be described. As shown in Fig. 1, the image forming apparatus 1 is a so-called multi-function peripheral (MFP) that combines a print function, a copy function, a facsimile function, a box function, etc., and includes an image forming unit 100, a paper feed unit 110, and an image reading unit 120.

[0033] The image forming unit 100 includes a control unit 101 and an operation panel 102. When the image forming unit 100 receives an image formation instruction from a user via the operation panel 102 or receives an image formation instruction from another device via the control unit 101, the image forming unit 100 executes an image formation process.

[0034] The paper feed unit 110 includes paper feed trays 111, 112, 113, and 114, and a manual feed tray 115. The paper feed unit 110 supplies recording sheets to be used in the image forming process by the image forming unit 100 from any of the paper feed trays 111, 112, 113, and 114, and the manual feed tray 115, to the image forming unit 100.

[0035] The image forming unit 100 forms an image on a recording sheet supplied from the paper feed unit 110 and then discharges the sheet onto a paper discharge tray 103 .

[0036] The image reading unit 120 can read an original document using either the sheet-through method or the platen-set method to generate color image data. When reading an original document using the sheet-through method, an automatic document feeder (ADF) 121 transports and reads the original document one sheet at a time from a stack of original documents.

[0037] As will be described later, when reading an original using the sheet-through method, both sides of the original can be read. Furthermore, when using the platen-set method, an original placed on a platen glass (not shown) is read. The image forming unit 100 performs image processing on the color image data generated by the image reading unit 120 according to the type of original, as will be described later. [2] Image reading unit 120 and automatic document feeder 121 Next, the configurations of the image reading unit 120 and the automatic document transport unit 121 will be described. (2-1) Image reading unit 120 2, the image reading section 120 includes a first reading unit 200, a contact glass 201, and a platen glass 203. When reading an original using the sheet-through method, the first reading unit 200 reads the original passing through a reading position 202 through the contact glass 201 while stopped at the position shown in FIG.

[0038] Hereinafter, the reading surface of the document that the first reading unit 200 reads in the sheet-through method will be referred to as the "first surface."

[0039] When reading a document using the platen set method, the document is placed on the platen glass 203, and the first reading unit 200 reads the document while sliding in the direction of arrow A. The first reading unit 200 slides in the direction of arrow A by a drive mechanism (not shown).

[0040] The first reading unit 200 includes an optical system 200d and a line sensor 200e, and the optical system 200d is made up of a light source 200a, a plurality of mirrors 200b, and an imaging lens 200c.

[0041] Light source 200a illuminates the first surface of the document across the document transport width direction (direction perpendicular to the transport direction) at reading position 202. Mirror 200d guides the light reflected from the document illuminated by light source 200a to imaging lens 200c.

[0042] The imaging lens 200c forms an image of the reflected light on the light receiving surface of the line sensor 200e, which then detects the amount of received light by photoelectrically converting the reflected light at each position in the transport width direction (main scanning direction) and generates color image data of the first side of the document.

[0043] When reading a document using the platen set method, the document is placed on the platen glass 203, and the first reading unit 200 slides in the direction of arrow A along the reading surface of the document, similar to the sheet-through method. (2-2) Automatic Document Feeder 121 The automatic document feeder 121 includes a second reading unit 210 , a document tray 211 , a pickup roller 212 , separation rollers 213 a and 213 b , a first transport roller 214 , a second transport roller 215 , a paper discharge roller 216 , and a paper discharge tray 217 .

[0044] A stack of documents to be read using the sheet-through method is placed on document tray 211. Pickup roller 212 feeds out documents one by one from the top of the document stack. Separation roller 213a rotates to transport documents in the document transport direction, and separation roller 213b rotates to transport documents in the opposite direction to the document transport direction.

[0045] As a result, when the pickup roller 212 sends out two or more documents from the document stack, causing a double feed, the separation roller 213a transports only the topmost document, while the separation roller 213b transports the documents other than the topmost document in a direction returning them to the document tray 211.

[0046] The first transport roller 214 transports the document to the reading position 202 of the first reading unit 200. The second transport roller 215 transports the document that has passed the reading position 202 of the first reading unit 200 to the reading position 220 of the second reading unit 210.

[0047] The paper discharge roller 216 discharges the document that has passed through the reading position 220 of the second reading unit 210 onto the paper discharge tray 217. The discharged documents are stacked on the paper discharge tray 217 one after another.

[0048] Generally, the first transport roller 214 and the second transport roller 215 are configured to be rotated by a common drive source (not shown). By adopting such a configuration, the image forming apparatus 1 can be made smaller.

[0049] The second reading unit 210 reads the second side of the document when reading both sides of the document using the sheet-through method. The second side of the document is the reverse side of the first side of the document that the first reading unit 200 reads.

[0050] The second reading unit 210, like the first reading unit 200, includes an optical system 210d and a line sensor 210e, and the optical system 210d is made up of a light source 210a, a plurality of mirrors 210b, and an imaging lens 210c.

[0051] Light source 210a illuminates the second side of the document across the width of the document at reading position 220. Mirror 210d guides the light reflected from the document illuminated by light source 210a to imaging lens 210c.

[0052] The imaging lens 210c forms an image of the reflected light on the light receiving surface of the line sensor 210e, which detects the amount of received light by photoelectrically converting the reflected light at each position in the transport width direction, and generates color image data of the second side of the document.

[0053] The first reading unit 200 and the second reading unit 210 may be contact image sensors (CIS).

[0054] In addition, in this embodiment, when a document is read using the sheet-through method without the user specifying the type of document, even in single-sided mode, not only the first side but also the second side of the document is read using the second reading unit 210.

[0055] The specification of the type of document may be received by the user operating the operation panel 102, or may be received by the control unit 101 from another device via a communication network. [3] Configuration of control unit 101 Next, the configuration of the control unit 101 will be described.

[0056] As shown in FIG. 3, the control unit 101 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, a HDD (Hard Disk Drive) 304, a NIC (Network Interface Card) 305, and a facsimile communication processing unit 306.

[0057] The CPU 301, ROM 302, RAM 303, HDD 304, NIC 305, and facsimile communication processor 306 are connected via an internal bus 307 so as to be able to communicate with each other.

[0058] When the image forming apparatus 1 is reset, for example, by being powered on, the CPU 301 reads and starts up a boot program from the ROM 302, and executes the OS (Operating System), control program, image processing program, etc. read from the HDD 304, using the RAM 303 as a working memory area.

[0059] The NIC 305 executes processing for communicating with other devices via a communication network such as a LAN (Local Area Network) or the Internet.

[0060] A facsimile communication processor 306 executes processing for facsimile communication with other facsimile devices via a facsimile line. Note that the NIC 305 may be used when facsimile communication is performed using e-mail.

[0061] The control unit 101 monitors and controls the operation and status of the image forming unit 100, operation panel 102, paper feed unit 110, image reading unit 120, and automatic document transport unit 121 by the CPU 301 executing a control program.

[0062] The operation panel 102 includes a touch panel, hard keys, a speaker, and a microphone. The touch panel is, for example, a liquid crystal display (LCD) with a touch pad superimposed on it, and presents information to the user via the LCD display and receives touch operations from the user via the touch pad.

[0063] The hard keys include a start key, numeric keypad, etc., and are used to accept key operations by the user. The speaker and microphone are provided for audio input and output. In addition to these, the operation panel 102 may be provided with a short-range communication interface such as Bluetooth (a registered trademark of Bluetooth SIG Inc.).

[0064] When the control unit 101 receives a scan instruction input from a user via the operation panel 102 or receives a scan job from another device via a communication network, it controls the image reading unit 120 and the automatic document transport unit 121 to read the document and generate color image data.

[0065] In addition, when the control unit 101 receives copy instructions input from a user via the operation panel 102 or receives a copy job from another device via a communication network, it controls the image reading unit 120 and the automatic document transport unit 121 to read the document and generate color image data, and then controls the image forming unit 100 and the paper feeding unit 110 to perform image formation processing using the generated color image data.

[0066] Furthermore, when the control unit 101 receives a facsimile transmission instruction from a user via the operation panel 102 or receives a facsimile transmission job from another device via a communication network, it controls the image reading unit 120 and the automatic document transport unit 121 to read the document and generate image data, and then transmits the generated image data by facsimile.

[0067] In this embodiment, after the document is read and color image data is generated, if the document is thermal paper and the image is degraded, image processing is performed on the color image data to correct the degraded image as described below. [4] Correction of degraded images Next, the correction process for a degraded image will be described.

[0068] When an echo image printed on thermal paper has deteriorated, the user of the image forming device 1 places the original on the thermal paper on the original tray 211 of the automatic original transport unit 121 of the image forming device 1 and instructs the process to be performed, such as scanning, copying, or facsimile transmission, after performing a correction process to bring the echo image as close as possible to its pre-deterioration state. (4-1) Main routine As shown in FIG. 4, when the image forming device 1 receives a scan instruction, copy instruction, or facsimile transmission instruction using the operation panel 102 or via a communication network (401: YES), it transports one document at a time from a stack of documents placed on the document tray 211 of the automatic document transport section 121, and at the reading position 202, it uses the first reading unit 200 to read the first side of the document and generate color image data for the first side, and at the reading position 220, it uses the second reading unit 210 to read the second side of the document and generate color image data for the second side (S402).

[0069] Next, the color image data of the first and second sides is used to determine whether the sheet type of the document is thermal paper. In the following, whether the sheet type of the document is thermal paper is determined based on whether the degraded image read from the document has characteristics specific to thermal paper, which appear when an image printed on thermal paper is degraded.

[0070] Thermal paper has a characteristic in that the thermal material applied to the image surface is prone to deterioration over time, and this deterioration increases the difference in the background color between the first and second sides. Based on this characteristic, if the difference in the background color between the first and second sides increases due to the deterioration of the image over time, it can be determined that the sheet type of the document is thermal paper.

[0071] For this purpose, first, the color image data of the first and second sides is used to determine the background colors of the front and back sides of the document (S403).

[0072] For example, for each pixel value of each pixel of the color image data (combination of RGB gradation values), the number of pixels with that pixel value may be counted, and the pixel value with the largest number of corresponding pixels may be set as the base color. Alternatively, the base colors of the first and second surfaces may be determined using other methods.

[0073] Next, the background color of the first surface is compared with the background color of the second surface to determine whether the difference between them has increased due to deterioration over time.

[0074] For example, if the pixel values ​​of the background color of the first surface are (R1, G1, B1) and the pixel values ​​of the background color of the second surface are (R2, G2, B2), the color difference D of the background color is D 2 =(R1-R2) 2 +(G1-G2) 2 +(B1-B2) 2 …(1) It can be defined as follows:

[0075] If the color difference D is greater than a predetermined threshold value, the background colors on the front and back of the document are different (S404: YES), and the document sheet type is determined to be thermal paper.

[0076] It goes without saying that the method for determining whether the base color is the same or different between the first and second surfaces is not limited to the above, and it goes without saying that other methods may be used to determine whether the base color is the same or different.

[0077] Even if the variation in the background color is not large (S404: NO), it is possible to determine whether the paper is thermal paper based on the deterioration of the image area. With thermal paper, deterioration of the image area rarely progresses uniformly across the entire surface of the document, and deterioration often occurs unevenly.

[0078] Furthermore, if we take into consideration that the pixel values ​​of the character parts of an image are often uniform before deterioration, it is possible to determine whether the document sheet type is thermal paper or not by whether the pixel values ​​(density) of the character parts are uniform.

[0079] Therefore, if the pixel values ​​of the character portion are not uniform (S405: NO), the document sheet type is determined to be thermal paper.

[0080] Furthermore, thermal paper tends to take on a reddish tinge when the black image portion deteriorates. Also, since characters are often printed in black, the color balance of the character portion is checked (S406). If the character portion is reddish and the gradation value of the R component in the pixel value is higher than the gradation values ​​of the other components, and therefore the intensity of the R component is high (S407: YES), the document sheet type is determined to be thermal paper.

[0081] If it is determined that the document sheet type is thermal paper (S404: YES, S405: NO, S407: YES), image correction processing suitable for thermal paper is executed (S408).

[0082] After the image correction process is performed, and if it is determined that the document sheet type is not thermal paper (S404: NO, S405: YES, S407: NO), and if a scan instruction has been received (S409: YES), the image data is saved in the save destination specified in the scan instruction (S410).

[0083] If a scan instruction has not been received (S409: NO) but a copy instruction has been received (S411: YES), image formation processing is executed using the image data (S412).

[0084] If a copy instruction has not been received (S411: NO), a facsimile transmission instruction has been received, so the image data is used to transmit the image by facsimile (S413).

[0085] If the document is to be read continuously after steps S410, S412 and S413 (S414: NO), the process proceeds to step S402 and the above processing is repeated.

[0086] If all the originals have been read (S414: YES), the process proceeds to step S401 to wait for the next instruction.

[0087] In this way, it is possible to determine whether the sheet type of the document from which the degraded image has been read is thermal paper, and to perform image correction processing suitable for thermal paper.

[0088] If it is determined that the sheet type of the document from which the degraded image was read is not thermal paper (S407: NO), before performing the conditional branching process of step S409, image processing such as correction processes such as level correction and gamma correction, compression or expansion of image data, and enlargement or reduction may be performed on the image data according to the content of the user instructions.

[0089] Furthermore, the processes from steps S409 to S413 may be executed after it is determined that the processes have been completed for all documents (S414: YES). (4-2) Image correction process (S408) Next, the image correction process will be described.

[0090] In the image correction process, first, the background color of the first side is matched to the background color of the second side (S501), as shown in Fig. 5. As shown in Fig. 6(a), initially, the background color 601 of the first side (front side) and the background color 602 of the second side (back side) of thermal paper are the same, but as shown in Fig. 6(b), while the background color 603 of the image side (front side) deteriorates over time, the background color 604 of the non-image side (back side) is less likely to deteriorate over time, so the initial background color is likely to be maintained on the non-image side.

[0091] Therefore, by matching the background color of the first surface to the background color of the second surface, the background color of the first surface can be made closer to the state before deterioration over time.

[0092] For example, as described above, if the pixel value with the largest number of pixels is used as the background color, the background color of the first surface can be matched to the background color of the second surface by changing the pixel value of the pixel of the background color of the first surface to the pixel value of the background color of the second surface.

[0093] Next, the redness of the printed portion of the first side is reduced (S502). As mentioned above, images printed on thermal paper tend to become reddish over time. To address this image degradation, the color balance can be adjusted to reduce the redness, taking into account that images printed on thermal paper are monochromatic.

[0094] For example, by adjusting the gradation value of the R component for each pixel to match the gradation values ​​of the other components, it is possible to reduce the redness of the printed part. The printed part is the part consisting of pixels other than the above background color pixels.

[0095] Next, sharpness is enhanced by image quality adjustment (S503). Generally, enhancing sharpness makes an image clearer. This also applies to degraded images. To enhance sharpness, for example, an edge enhancement filter can be used.

[0096] Furthermore, if a copy instruction has been received (S504: YES), the printing conditions are changed from color mode to black and white mode (S505), and the darkness setting (copy density setting) in black and white mode is maximized (S506).The contrast level adjustment may also be maximized.

[0097] In this way, by enhancing the contrast of a degraded image that has been reduced by the deterioration of thermal paper over time, it is possible to make the image closer to the original image. It goes without saying that the contrast of a degraded image can also be enhanced by image processing rather than as a printing condition.

[0098] In this way, the difference in tone is emphasized in the printed image, so that a clear printed image can be obtained.

[0099] Furthermore, when a deteriorated image is copied in auto color mode and is determined to be color, the quality of the copied image is likely to be reduced, but by doing as described above, the image is copied in monochrome mode, so that the reduction in the quality of the copied image can be avoided. [5] Characteristics of manuscript sheet types To determine the type of document sheet, attention must be paid to the characteristics of the sheet. (5-1) Thermal paper Thermal paper is made by mixing two chemicals - a colorless dye (usually a leuco dye) that is solid at room temperature and melts at a certain temperature, and a color developer (a substance that reacts with the leuco dye and causes it to develop color) that melts at about the same temperature as the leuco dye, along with adhesives and auxiliary agents (sensitizers, stabilizers). An overcoat may also be applied to prevent color development due to friction.

[0100] When heat is applied to thermal paper, the leuco dye and developer melt and mix at the heated points, causing the leuco dye and developer to react and produce color. The color-producing temperature is often set at 55-60°C.

[0101] The reaction between the leuco dye and the developer is reversible, and if the reaction reverses over time, the image will fade. To prevent this, stabilizers and other additives are added to thermal paper, but this does not completely eliminate the fading.

[0102] Because thermal paper changes color when heated, it is not suitable for double-sided printing. When the front side is heated, the back side is also heated and changes color. For this reason, the thermal agent is coated on only one side of the thermal paper. Therefore, although the difference between the front and back of thermal paper is small at first, the difference increases as the paper deteriorates over time.

[0103] For example, if the surface coated with the heat-sensitive agent is continuously exposed to external light, the above-mentioned reverse reaction will be easily accelerated, resulting in discoloration. Also, if the surface comes into contact with a chemical that decomposes the leuco dye, the reverse reaction will be easily accelerated when the leuco dye is decomposed, resulting in discoloration.

[0104] Many commonly used chemicals break down leuco dyes, including alcohol, acetone, and ammonia. Acetone is found in nail polish remover, and ammonia is sometimes found in home remedies such as Kinkan (a registered trademark of Kinkando Co., Ltd.). For this reason, it is not uncommon for these chemicals to adhere to thermal paper and cause discoloration.

[0105] If the fading of the image has not progressed much, the contrast of the deteriorated image can be enhanced to make it closer to the image before deterioration. (5-2) Coated paper Coated paper is a general term for paper whose surface is coated with a coating agent, making it smoother and glossier than regular paper.

[0106] Coated paper is characterized by its smooth surface, which allows ink to adhere well, its excellent photo and color reproduction, its glossy, lustrous appearance, its quick drying ink, and its short printing time.

[0107] Coated paper is made from high-quality or medium-quality paper, and is 20 g / m 2 ~40g / m 2 It is a printing paper coated with a coating of the above paint. The coating is made by mixing a white pigment such as clay with an adhesive such as starch.

[0108] In addition to coated paper, glossy paper, which has a glossy surface, is widely used for printing with inkjet printers. Glossy paper is mainly used for photographic printing, and is often used as photo paper for home printers.

[0109] Coated paper has the same glossiness as glossy paper, but since inkjet printers heat the paper when ejecting the ink, this heat can act on the coating agent, causing bubbles to form, making it unsuitable for printing with inkjet printers.

[0110] On the other hand, when using an electrophotographic printer, coated paper has high color reproducibility, so it is often used for printed materials where you want to display images clearly in full color.

[0111] However, whether using the inkjet method or the electrophotographic method, coated paper can have difficulty in fixing ink to the coating on its surface. In such cases, the image deteriorates. Therefore, if the document sheet type is coated paper, image quality can be improved by assuming localized fixing problems and performing image processing to compensate for them by averaging the pixel values ​​of the affected areas.

[0112] Furthermore, because coated paper has a smooth surface due to the coating agent that coats the surface, it is not suitable for adding notes with a pencil or ballpoint pen or for stamping. For this reason, if the handwritten manuscript is on coated paper, it is effective to apply image processing to correct faint or faded handwriting. (5-3) Carbon paper Carbon paper is a sheet used by placing it between documents to make copies of handwritten text. It is sometimes simply called "carbon." The pressure of the writing is transmitted through the paper on top to the carbon paper and then to the paper underneath, causing the carbon coated on the underside of the carbon paper to bleed through to the paper underneath. It is also used as copy paper for impact printers.

[0113] Back-carbon copy paper (back carbon paper) has come to be used for handwritten input slips and other documents, eliminating the need for carbon paper. Back-carbon paper (back carbon paper) has carbon applied directly to the back of the paper, such as a slip, so it can be copied onto the paper below without having to insert carbon paper between the sheets. With back-carbon paper, you only need to apply carbon to the handwritten parts that need to be copied, and this carbon applied only to the parts that need to be copied is called spot carbon paper.

[0114] When carbon paper is used to copy handwritten text, the carbon applied to the back of the paper is lost only in the handwritten portion, so when you look at the back of the carbon paper, you can see the handwritten text reversed.

[0115] Therefore, even if the handwritten portion on the front side of the carbon back paper becomes damaged due to soiling or other reasons, the handwritten portion on the front side can be restored by reading the carbon portion on the back side and inverting the image. In other words, if the document sheet type is carbon back paper, by performing this type of image processing, the degraded image read from the damaged front side can be corrected to approach the state before the damage. [6] Variation The present disclosure has been described above based on the embodiments, but it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples can be implemented. (6-1) In the above embodiment, the example was explained using a case where an image on a thermal paper document has deteriorated. However, it goes without saying that the present disclosure is not limited to this, and similar effects can be obtained by applying the present disclosure to cases where an image on coated paper or carbon paper has deteriorated instead of thermal paper.

[0116] In the above embodiment, whether the document is thermal paper or not is determined by reading and comparing both sides of the document, but in the case of a document made of coated paper or carbon paper, the sheet type may alternatively be determined using a known sheet discrimination means.

[0117] For example, in addition to the above, when the surface coating layer of coated paper deteriorates over time, the image may fade.

[0118] In addition, pressure-sensitive coloring copy paper (carbonless paper), in which the paper itself changes color with pen pressure (impact), can become discolored or the colored characters can fade if exposed to sunlight for a long period of time.

[0119] By correcting the read data in accordance with the image degradation characteristics specific to the document sheet type, it is possible to make the image closer to the original. (6-2) In the above embodiment, an example has been described in which an edge enhancement filter is used to enhance sharpness. However, it goes without saying that the present disclosure is not limited to this, and when a copy instruction is received, a setting to enhance sharpness may instead be made in the printing conditions.

[0120] In this way, the degraded image can be corrected to approach the original image. (6-3) In the above embodiment, the first side of the document is the image side, but it goes without saying that the present disclosure is not limited to this, and the following may be used instead.

[0121] That is, in the image correction process (S408), first, it may be determined whether the first or second surface is the image surface, and correction processing may be performed on the image data of the image surface.

[0122] Since thermal paper documents have an image printed on the image side and the non-image side is white, either the first or second side will be a solid white image. By focusing on this fact and performing correction processing on the image data that is not a solid white image, it is possible to correct the degraded image. (6-4) In the above embodiment, an example was given of determining whether the sheet type of a document is thermal paper using a degraded image read from the document and an image read from the back side of the degraded image. However, it goes without saying that the present disclosure is not limited to this, and instead, the following may be used.

[0123] For example, if the user can determine the sheet type of the document, the user may specify the sheet type of the document using, for example, the operation panel 102. If the sheet type of the document specified by the user is thermal paper, the image correction process (S408) described in the above embodiment can be executed to correct the degraded image and bring it closer to the image before degradation. (6-5) Although not specifically mentioned in the above embodiment, in order to change the color mode to the black and white mode in step S505 of FIG. 5, for example, the following may be done.

[0124] When the image forming apparatus 1 operates in the so-called automatic color mode (ACS: Automatic Color Selection), if the average saturation of the printed portion of the image to be formed is equal to or greater than a predetermined threshold, the image is determined to be a full-color image, and if the average saturation is less than the predetermined threshold, the image is determined to be a monochrome image, and the image is formed.

[0125] In such a case, if the document sheet type is thermal paper, by increasing the threshold value of the auto color mode, the image printed on the thermal paper is a monochrome image, and it is possible to reliably determine that the image that has undergone processing up to step S503 in Figure 5 is a monochrome image. (6-6) In the above embodiment, the image forming device 1 is described as a multifunction device. However, the present disclosure is not limited to this, and the image forming device 1 may be a single-function device with a scanning function, such as a copy machine or a facsimile machine.

[0126] Furthermore, the image forming apparatus 1 may form images by electrophotography, or may form images by a method other than electrophotography, such as inkjet.

[0127] In either case, if the present disclosure is applied, it is possible to correct the degraded image and obtain an image that is close to the original image. (6-7) In the above embodiment, the image forming apparatus 1 has been described as an example, but it goes without saying that the present disclosure is not limited to this, and instead, the present disclosure may be an image processing method executed by the image forming apparatus 1. By implementing the image processing method according to the present disclosure, a degraded image can also be corrected with high accuracy. [Industrial Applicability]

[0128] The image processing device, image reading device, image forming device, and image processing method according to the present disclosure are useful as devices and methods capable of appropriately restoring a deteriorated image. [Explanation of symbols]

[0129] 1. Image forming device 100...Image forming unit 101...Control unit 102...Operation panel 110…Paper feed section 120...Image reading unit 121...Automatic document feeder 200...First reading unit 201...Contact glass 202, 220...Reading positions 210...Second reading unit 211...Document tray

Claims

1. An image processing device that processes an image read from an original, an identification means for identifying the sheet type of the document; a determining means for determining whether or not image deterioration specific to the specified sheet type has occurred based on the image read from the document; and a correction means for executing image processing to correct the deteriorated image when the determination means determines that image deterioration has occurred.

1. An image processing device comprising:

2. The correction means corrects the deteriorated image so that it approaches the image before deterioration.

2. The image processing device according to claim 1, wherein:

3. 3. The image processing apparatus according to claim 1, wherein the correction means corrects at least one of a background color and a character portion in the degraded image.

4. The identifying unit identifies the sheet type of the document using the degraded image.

4. The image processing device according to claim 1, wherein the image processing device is a computer.

5. The specifying unit specifies the sheet type of the document depending on which of predetermined sheet types has image degradation due to a characteristic specific to that type.

5. The image processing device according to claim 4.

6. The identifying means identifies whether the sheet type of the document is thermal paper.

6. The image processing device according to claim 4, wherein:

7. The identifying unit identifies the sheet type of the document as thermal paper when the background color of the degraded image is different from that of an image obtained by reading the back side of the degraded image of the document.

7. The image processing device according to claim 6,

8. The identifying means identifies the sheet type of the document as thermal paper when the density of the character portion in the degraded image is not uniform.

7. The image processing device according to claim 6,

9. The identifying means identifies the sheet type of the document as thermal paper when the character portion of the degraded image is reddish.

7. The image processing device according to claim 6,

10. When the sheet type of the document is thermal paper, the correction means executes image processing to match the background color of the degraded image with the background color of an image obtained by reading the back side of the degraded image of the document.

10. The image processing device according to claim 6, wherein:

11. The correction means performs image processing to enhance the contrast of the degraded image when the sheet type of the document is thermal paper.

11. The image processing device according to claim 6,

12. The correction means performs image processing to enhance the sharpness of the degraded image when the sheet type of the document is thermal paper.

12. The image processing device according to claim 6, wherein:

13. The correction means performs image processing to reduce redness of printed portions in the degraded image when the sheet type of the document is thermal paper.

13. The image processing device according to claim 6, wherein:

14. reading means for reading an image from an original; and an image processing device according to any one of claims 1 to 13, which processes the image read from the document by the reading means. An image reading device characterized by:

15. an image processing device according to any one of claims 1 to 13; and an image forming means for forming an image using a processed image obtained by image processing of the image processing device. An image forming apparatus characterized by:

16. The image reading device according to claim 14; and an image forming means for forming an image using a processed image obtained by image processing of the image processing device. An image forming apparatus characterized by:

17. a color mode discrimination means for discriminating the processed image as a full-color image when the average saturation of the print portion of the processed image is equal to or greater than a predetermined threshold, and for discriminating the processed image as a monochrome image when the average saturation is less than the predetermined threshold; the color mode determining means changes the predetermined threshold value so that the processed image is determined to be a monochrome image when the sheet type of the document is thermal paper; The image forming means forms the processed image in accordance with the determination result of the color mode determining means.

17. The image forming apparatus according to claim 15 or 16.

18. The image forming means forms the processed image as a monochrome image when the sheet type of the document is thermal paper.

17. The image forming apparatus according to claim 15 or 16.

19. The image forming means maximizes the density setting when forming the processed image as a monochrome image.

19. The image forming apparatus according to claim 18.

20. An image processing method for processing an image read from an original, comprising: a step of identifying the sheet type of the document; a determining step of determining whether or not image degradation specific to the specified sheet type has occurred based on the image read from the document; a correction step of executing image processing to correct the deteriorated image when it is determined that image deterioration has occurred in the determination step. An image processing method comprising:

Images