WO2020045766A1

WO2020045766A1 - Color conversion based on color space and object properties

Info

Publication number: WO2020045766A1
Application number: PCT/KR2018/016703
Authority: WO
Inventors: Joo Young Jung; Joo Duck Kim
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2018-08-30
Filing date: 2018-12-27
Publication date: 2020-03-05
Also published as: KR20200025536A

Abstract

An apparatus for processing a printing job target is provided. The apparatus includes a processor and a non-transitory computer-readable storage medium having stored therein instructions executable by the processor. The processor may execute the instructions to render the printing job target according to a standard color space corresponding to original colors of the printing job target and to convert the rendered printing job target according to a color space supported by the image forming apparatus based on a standard color space and an object property of the rendered printing job target.

Description

COLOR CONVERSION BASED ON COLOR SPACE AND OBJECT PROPERTIES

An image forming apparatus such as a color printer may output various colors presented in contents of a document by combining primary colors of cyan, magenta, yellow, and black (CMYK). However, the original colors of the document may have a color space, such as red, green, and blue (RGB), which is different from a CMYK color space. Therefore, during output of the document, color matching is required for proper conversion of the original colors of the contents of the document in the color space supported by the image forming apparatus.

The above and other aspects, features, and advantages of various examples of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram for describing a printing service environment including an image forming apparatus and an apparatus for processing a printing job target, according to an example;

FIG. 2 is a block diagram for describing components and operations of each of an image forming apparatus and an apparatus for processing a printing job target, according to an example;

FIG. 3 is a diagram for describing a process of processing a printing job target, according to an example;

FIG. 4 is a view for describing a process of rendering a printing job target in a process of processing the printing job target, according to an example;

FIG. 5 is a view for describing a process of converting a rendered printing job target in a process of processing the printing job target, according to an example;

FIG. 6 is a diagram for describing a lookup table corresponding to an object property of a rendered printing job target, according to an example;

FIG. 7 is a diagram for describing processing of a printing job target when the printing job target is a scanned document, according to an example; and

FIG. 8 is a flowchart illustrating a method of processing a printing job target, according to an example.

Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, parts, components, and structures.

Hereinafter, various examples will be described with reference to the accompanying drawings. The examples described hereinafter may be modified in many different forms. To more clearly describe features of examples, matters well known to one of ordinary skill in the art to which the below examples pertain will not be described in detail.

In the specification, an "image forming job" may denote any one of various jobs (for example, printing, copying, scanning, and faxing) related to an image, such as forming of an image or generating/storing/transmitting of an image file, and a "job" may denote not only an image forming job, but may also denote a series of processes required to perform the image forming job.

FIG. 1 is a diagram for describing a printing service environment including an image forming apparatus and an apparatus for processing a printing job target, according to an example.

Referring to FIG. 1, an image forming apparatus 100 may perform an image forming job such as printing, copying, scanning, faxing, and the like. The image forming apparatus 100 may form an image on a recording medium such as print paper by using various printing schemes such as an electrophotography scheme, an inkjet scheme, a thermal transfer scheme, a direct thermal scheme, and the like. An apparatus 200 for processing the printing job target may be a computing device such as a smart phone, a laptop computer, and the like. For example, when a user who is working on a document using a running application installed on a laptop computer desires to print the document, the user may send a printing job target to the image forming apparatus 100.

FIG. 2 is a block diagram for describing components and operations of each of an image forming apparatus and an apparatus for processing a printing job target, according to an example.

Referring to FIG. 2, the image forming apparatus 100 may include a user interface device 110, a processor 120, a memory 130, a communication interface 140, and an image forming job unit 150. Although not shown, a power supply unit for supplying power to each component may be further included in the image forming apparatus 100.

The user interface device 110 may include an input unit for receiving an input for performing an image forming job, or the like from the user and an output unit for displaying information such as a result of performing the image forming job, a state of the image forming apparatus 100, or the like. For example, the user interface device 110 may have the form of a touch screen including an operation panel that receives a user input, a display panel that displays a screen, and so forth.

The processor 120 may control an operation of the image forming apparatus 100, and may include at least one processing unit such as a central processing unit (CPU), or the like. The processor 120 may control other components included in the image forming apparatus 100 to perform an operation corresponding to the user input received through the user interface device 110. The processor 120 may include at least one specialized processing unit corresponding to each unit or may have an integral form.

The processor 120 may execute a program stored in the memory 130, read data or a file stored in the memory 130, or store a new file in the memory 130.

The memory 130 may install and store a program such as an application and various types of data such as a file or the like. The processor 120 may access and use data stored in the memory 130 or store new data in the memory 130. The processor 120 may execute a program installed in the memory 130. The processor 120 may also install an application, which is received from an external source through the communication interface 140, in the memory 130.

The communication interface 140 may perform wireless/wired communication with another device or a network. To this end, the communication interface 140 may include a communication module (e.g., transceiver) supporting at least one of various wireless/wired communication methods. For example, a communication module may have the form of a chipset or may be a sticker/barcode (e.g., a sticker including a near field communication (NFC) tag), or the like.

The wireless communication may include, for example, wireless fidelity (Wi-Fi), Wi-Fi Direct, Bluetooth, ultra-wide band (UWB), NFC, and so forth. The wired communication may include, for example, ethernet, universal serial bus (USB), a high definition multimedia interface (HDMI), and so forth.

The communication interface 140 may be connected with an external device located outside the image forming apparatus 100 and transmit and receive a signal or data to and from the external device. The communication interface 140 may deliver the signal or the data received from an external device to the processor 120 or transmit a signal or data generated in the processor 120 to the external device. For example, once the communication interface 140 receives a print command signal and a printing job target from the external device, the processor 120 may output the received printing job target through a printing unit 151.

The image forming job unit 150 may perform an image forming job such as printing, copying, scanning, faxing, and the like. While it is illustrated in FIG. 2 that the image forming job unit 150 includes the printing unit 151, a scanning unit 152, and a faxing unit 153, the image forming job unit 150 may include only some components thereof or may further include components to perform other types of image forming jobs.

The printing unit 151 may form an image on a recording medium by using various printing schemes such as an electrophotography scheme, an inkjet scheme, a thermal transfer scheme, a direct thermal scheme, and the like. The scanning unit 152 may read an image recorded on a manuscript by irradiating light onto the manuscript and receiving light reflected therefrom. The faxing unit 153 may share a component for scanning an image with the scanning unit 152, share a component for printing a received file with the printing unit 151, and transmit a scanned file to a destination or receive a file from an external source.

The apparatus 200 for processing a printing job target according to an example may include a memory 210, a processor 220, and a communication interface 230. The apparatus 200 for processing the printing job target may be a host device that requests a printing operation from the image forming apparatus 100.

The memory 210 may store instructions executable by the processor 220. Also, the memory 210 may store an operating system and application programs.

The processor 220 may execute instructions stored in the memory 210 to generate a printing job target in response to a print request from an application. When the processor 220 generates the printing job target as a print command, the processor 220 may generate the print command by including an object tag therein according to a type of contents of an object of the printing job target for raster data. For example, the processor 220 may consider a palette color or entire gamut of raster data to determine whether the raster data is color or black and white, thereby identifying the object tag for the raster data as photo raster or grayscale raster. The processor 220 may also identify the object tag as text raster using optical character recognition (OCR) and as graphical raster through histogram analysis. The print command for the printing job target may be generated to include the object tag identified in this way.

The processor 220 may perform a process of processing the printing job target in the form of a print command to allow the image forming apparatus 100 to perform a printing operation in a color space supported by the image forming apparatus 100. The processor 220 may perform the entire process of processing the printing job target or a part thereof to allow the image forming apparatus 100 to immediately perform a printing operation.

For example, the processor 220 of the apparatus 200 for processing the printing job target may, by executing instructions, render the printing job target according to a standard color space corresponding to the original colors of the printing job target and convert the rendered printing job target according to a color space supported by the image forming apparatus 100 based on a standard color space and an object property of the rendered printing job target. The apparatus 200 for processing the printing job target may convert the rendered printing job target through color matching between colors in the standard color space corresponding to the original colors of the printing job target and colors in the color space supported by the image forming apparatus 100. The processor 220 may transmit the printing job target having undergone a predetermined processing process to the image forming apparatus 100 through the communication interface 230.

Hereinafter, an example of a process of processing a printing job target to represent colors that are most similar to the original colors of a document in the color space supported by an image forming apparatus will be provided.

FIG. 3 is a diagram for describing a process of processing a printing job target, according to an example.

Referring to FIG. 3, to perform a printing operation such as color printing in the image forming apparatus 100, a series of processes with respect to a printing job target may be performed. According to cyan, magenta, yellow, and black (C, M, Y, and K) toner characteristics supported in the image forming apparatus 100, conversion of the printing job target into colors of the color space supported by the image forming apparatus 100 may be required. That is, the apparatus 200 for processing the printing job target may generate a bitmap in an intermediate color space after rendering of the printing job target generated as the print command, convert the generated bitmap into a bitmap in the color space supported by the image forming apparatus 100, that is, the CMYK color space, and generate CMYK binary data through halftoning. For conversion into the bitmap in the CMYK color space and halftoning, a unique lookup table based on characteristics of the image forming apparatus 100 may be used.

As illustrated in FIG. 3, a printing job target may be divided into a plurality of regions according to a color space of the original and a type of contents of the original. In the example of FIG. 3, the printing job target may be divided into four

regions

①, ②, ③, and ④.

As may be seen from FIG. 3, the four regions of the printing job target may correspond to a plurality of color spaces rather than one color space. For example, the region ① may correspond to the CMYK color space, and the

regions

③ and ④ may correspond to the RGB color space. The region ③ may correspond to a color photo, and the region ④ may correspond to a grayscale of black and white. That is, the printing job target is divided into a plurality of regions according to the color space of the original and the type of the contents of the original, and, to represent colors of the original as much as possible, a printing operation based on characteristics of each region should be performed.

The apparatus 200 for processing the printing job target may render the printing job target according to the standard color space corresponding to the original colors of the printing job target. As stated above, the region ① corresponds to the CMYK color space and the region ③ corresponds to the RGB color space., When the two regions are generated as bitmaps in the same intermediate color space, an error may occur due to a color space difference during rendering. As illustrated in FIG. 3, when a plurality of standard color spaces correspond to the original colors of the printing job target, rendering of the printing job target according to each standard color space may improve a color representation rate.

When the color space corresponding to the original colors of the printing job target has a larger gamut than the intermediate color space, generation of a bitmap according to the intermediate color space may degrade color quality. Moreover, when the user manufactures the original of the printing job target according to the CMYK color space, taking the output of the image forming apparatus 100 into account, generation of a bitmap according to the intermediate color space of a type that is different from the RGB color space may lead to an inability to adequately reflect color values intended in the original. Thus, rendering of the printing job target according to the standard color space corresponding to the original colors of the printing job target may be a way to maintain the quality of the original colors.

FIG. 4 is a view for describing a process of rendering a printing job target in a process of processing the printing job target, according to an example.

Referring to FIG. 4, when the apparatus 200 for processing the printing job target renders the printing job target according to a standard color space corresponding to the original colors of the printing job target, the apparatus 200 may generate a bitmap corresponding to the printing job target according to the standard color space and generate an object map based on an object property of the printing job target according to an object tag included in the printing job target.

As illustrated in FIG. 4, the apparatus 200 for processing the printing job target may generate the object map based on the object properties of the printing job target based on the object tag corresponding to a type of contents of each region of the printing job target. For example, for the region ④ in which the object tag corresponds to the grayscale raster data, the apparatus 200 may configure the object map by assigning grayscale properties. The object properties may be defined in more detail than the object tag, and thus the number of object properties may be greater than that of object tags. Referring to FIG. 4, there may be various object properties such as background, raster, text, graphic, small text, pattern, and so forth, and an object map may be configured with a color space value, a sub type value, and a basic object value that differ according to each object property. For example, for the object property, background, an object map may have a value of "11111111" including a color space value of "111", a sub type value of "11", and a basic object value of "111". However, the value of the object map according to the object property is not limited to the example illustrated in FIG. 4, and may be adjusted. The object property configuring the object map may be used to convert the rendered printing job target according to the color space supported by the image forming apparatus 100.

Referring back to FIG. 3, the apparatus 200 for processing the printing job target may convert the rendered printing job target according to a color space supported by the image forming apparatus 100 based on a standard color space and an object property of the rendered printing job target. The apparatus 200 for processing the printing job target may convert the rendered printing job target through color matching using a lookup table corresponding to the object property of the rendered printing job target.

FIG. 5 is a view for describing a process of converting a rendered printing job target in a process of processing the printing job target, according to an example.

Referring to FIG. 5, with respect to the rendering result of the printing job target described with reference to FIG. 4, that is, a bitmap rendered according to the standard color space of the original colors and an object map indicating an object property, color matching may be performed using a lookup table corresponding to the object property. The lookup table may be provided for each object property, and thus a plurality of lookup tables may be used depending on a type of an object property included in a printing job target. A value of an object map corresponding to an object property and a lookup table corresponding to the object property may be mapped to each other. Thus, when a rendered printing job target is converted according to a color space supported by the image forming apparatus 100, a lookup table corresponding to an object property may be retrieved based on a value of an object map and may be used for color matching.

In an example, the rendered printing job target is converted according to the CMYK color space supported by the image forming apparatus 100, and a region indicating an object property may be converted according to a specific policy. For example, for the region ④, an object property is grayscale raster, such that the region ④ may be converted to have pure black using only a black toner supported by the image forming apparatus 100.

FIG. 6 is a diagram for describing a lookup table corresponding to an object property of a rendered printing job target, according to an example.

Referring to FIG. 6, when a rendered printing job target is converted using color matching, color matching is performed using a lookup table corresponding to an object property appearing on an object map. In FIG. 6, lookup tables correspond to raster, text, and graphic, respectively, in which for raster, a composite black lookup table having only composite black using C, M, Y, and K toners is used, and for text or graphic, a pure black lookup table having pure black using only the K toner is used. While the lookup tables corresponding to raster, text, and graphic, respectively, have been described with reference to FIG. 6, the present disclosure is not limited thereto and a lookup table may be provided for each object property.

FIG. 7 is a diagram for describing processing of a printing job target when the printing job target is a scanned document, according to an example.

Referring to FIG. 7, the above-described process of processing the printing job target is applicable to not only a process of printing a document, but also a case where a printing job target is a scanned document. However, when the printing job target is a scanned document, the entire page region of the scanned document may be determined as one raster. Thus, the process of processing a printing job target like one raster is performed, and the scanned document is divided into several regions, for each of which an object property is designated.

Referring to FIG. 8, a user may open a document by executing an application, and may generate a printing job target in response to a print request from the application. The printing job target may be generated in the form of a print command including an object tag corresponding to a type of contents of an object constituting the printing job target. With respect to such a printing job target, the apparatus 200 for processing the printing job target may process the printing job target according to an example method described below.

The apparatus 200 for processing the printing job target renders the printing job target according to a standard color space corresponding to the original colors of the printing job target in operation S810. The apparatus 200 for processing the printing job target may render the printing job target according to a plurality of standard color spaces when the plurality of standard color spaces correspond to the original colors of the printing job target. The apparatus 200 for processing the printing job target may generate a bitmap corresponding to the printing job target according to the standard color space and generate an object map based on an object property of the printing job target according to an object tag included in the printing job target. The object tag may be any one of photo raster, grayscale raster, text raster, or graphic raster, and the object tag may be generated corresponding to a type of contents of the printing job target when a print command is generated in response to a print request.

The apparatus 200 for processing the printing job target converts the printing job target rendered according to the color space supported by the image forming apparatus 100 based on the standard color space and the object property of the rendered printing job target in operation S820. The apparatus 200 for processing the printing job target may convert a bitmap of a rendered intermediate color space into a bitmap of a color space supported by the image forming apparatus 100, for example, the CMYK color space. The apparatus 200 for processing the printing job target may convert the rendered printing job target through color matching using a lookup table corresponding to the object property of the rendered printing job target. The apparatus 200 for processing the printing job target may convert an object included in the rendered printing job target to use only the black toner supported by the image forming apparatus 100, when an object property of the object included in the rendered printing job target is grayscale raster.

Once the rendered printing job target is converted according to the color space supported by the image forming apparatus 100, halftoning is performed, thus generating CMYK binary data. The CMYK binary data is delivered to the image forming job unit 150 of the image forming apparatus 100, and the image forming job unit 150 performs printing using the CMYK binary data.

In an example, the operation of rendering the printing job target and the operation of converting the rendered printing job target may be performed by the image forming apparatus 100 as well as the apparatus 200 for processing the printing job target, which is a host device. Alternatively, the apparatus 200, as the host device for processing the printing job target, may perform the operation of rendering the printing job target, and the image forming apparatus 100 may perform the operation of converting the rendered printing job target.

The foregoing disclosure may be implemented in the form of a non-transitory computer-readable storage medium having stored therein instructions or data executable by a computer or a processor. The foregoing disclosure may also be written as programs executable on computers, and may be implemented on general-purpose digital computers operating the programs by using computer-readable storage media. Examples of the non-transitory computer-readable storage media may include read-only memory (ROM), random-access memory (RAM), flash memory, compact disc (CD)-ROMs, CD-recordables (CD-Rs), CD+Rs, CD-rewritables (RWs), CD+RWs, digital versatile disc (DVD)-ROMs, DVD-Rs, DVD+Rs, DVD-RWs, DVD+RAMs, Blue-ray(BD)-ROMs, BD-recordables (Rs), BD-R low-to-high (LTHs), BD-rewritables (REs), magnetic tapes, floppy disks, magneto-optical data storage devices, optical data storage devices, hard disks, solid state disks (SSDs), and any device capable of storing instructions or software, related data, data files, and data structures, and providing the instructions or the software, the related data, the data files, and the data structures to a processor or a computer to enable the processor or the computer to execute the instructions.

While this disclosure has been shown and described with reference to examples thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure. That is, the scope of the disclosure is defined not by the description of the disclosure but by the appended claims, and all differences within the scope will be construed as being included in the present disclosure.

Claims

An apparatus for processing a printing job target, the apparatus comprising:

a processor; and

a memory storing instructions executable by the processor,

wherein the processor is to execute the instructions to:

render a printing job target according to a standard color space corresponding to original colors of the printing job target; and

convert the rendered printing job target according to a color space supported by an image forming apparatus, based on the standard color space and an object property of the rendered printing job target.
The apparatus of claim 1, wherein the memory stores further instructions that cause the processor to render the printing job target according to a plurality of standard color spaces when the plurality of standard color spaces correspond to the original colors of the printing job target.
The apparatus of claim 1, wherein the memory stores further instructions that cause the processor to:

generate a bitmap corresponding to the printing job target according to the standard color space; and

generate an object map based on the object property of the printing job target according to an object tag included in the printing job target.
The apparatus of claim 3, wherein the object tag comprises at least one of photo raster, grayscale raster, text raster, or graphics raster.
The apparatus of claim 1, wherein the memory stores further instructions that cause the processor to convert an object included in the rendered printing job target to use a black toner supported by the image forming apparatus, when an object property of the object included in the rendered printing job target is grayscale raster.
The apparatus of claim 1, wherein the memory stores further instructions that cause the processor to convert the rendered printing job target through color matching using a lookup table corresponding to the object property of the rendered printing job target.
The apparatus of claim 1, wherein at least one of:

a host device renders the printing job target and the image forming apparatus converts the rendered printing job target, or

either of the host device or the image forming apparatus renders the printing job target and converts the rendered printing job target.
A method of processing a printing job target, the method comprising:

rendering a printing job target according to a standard color space corresponding to original colors of the printing job target; and

converting the rendered printing job target according to a color space supported by an image forming apparatus, based on the standard color space and an object property of the rendered printing target.
The method of claim 8, wherein the rendering comprises rendering the printing job target according to a plurality of standard color spaces when the plurality of standard color spaces correspond to the original colors of the printing job target.
The method of claim 8, wherein the rendering comprises:

generating a bitmap corresponding to the printing job target according to the standard color space; and

generating an object map based on the object property of the printing job target according to an object tag included in the printing job target.
The method of claim 10, wherein the object tag comprises at least one of photo raster, grayscale raster, text raster, or graphic raster.
The method of claim 8, wherein the converting comprises converting an object included in the rendered printing job target to use a black toner supported by the image forming apparatus, when an object property of the object included in the rendered printing job target is grayscale raster.
The method of claim 8, wherein the converting comprises converting the rendered printing job target through color matching using a lookup table corresponding to the object property of the rendered printing job target.
The method of claim 8, wherein at least one of:

the rendering of the printing job target and the converting of the rendered printing job target are performed by either a host device or an image forming apparatus, or

the rendering of the printing job target is performed by the host device and the converting of the rendered printing job target is performed by the image forming apparatus.
A non-transitory computer-readable storage medium storing instructions executable by a processor, the non-transitory computer-readable storage medium comprising:

instructions to render a printing job target according to a standard color space corresponding to original colors of the printing job target; and

instructions to convert the rendered printing job target according to a color space supported by an image forming apparatus, based on the standard color space and an object property of the rendered printing target.