Patent Application
20110110589
The present application relates generally to contrast enhancement of digitally encoded images and to improved, automatic contrast enhancement that avoids application of enhancement to certain categories of images.
Images include visual properties such as contrast, which is a property that makes an object distinguishable from other objects or background depicted in the image by relative lightness and darkness. Often visual properties of an image can be approved by adjusting contrast. When images are captured in a digitally encoded format, mathematical manipulation of corresponding image data can be used to adjust contrast of a resultant rendered image.
Alterations in contrast are frequently completed by computer users who can manipulate image data using suitable software. However, it is difficult for users to generate an improved image using manual adjustment of contrast properties. Automated contrast adjustment exists, but may be applied to all images, irrespective of image type. This may result in degraded image quality or negation of intentional image effects. In addition, automated contrast adjustment is frequently made solely on properties of one particular image.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. The subject application is described with reference to certain figures, including:
The subject application is directed to a system and method for image contrast enhancement. The subject application is directed generally to contrast enhancement of digitally encoded images and is particularly applicable to improved, automatic contrast enhancement that avoids application of enhancement to certain categories of images. In this patent, the terms “automatic” and “automatically” mean “without operator involvement”. It will become apparent to those skilled in the art that the system and method described herein are suitably adapted to a plurality of varying electronic fields employing iterative processing, including, for example and without limitation, communications, general computing, data processing, document processing, financial transactions, vending of products or services, or the like. The preferred embodiment, as depicted in
Referring now to
The system 100 also includes a document processing device 104, which is depicted in
According to one embodiment of the subject application, the document processing device 104 is suitably equipped to receive a plurality of portable storage media, including, without limitation, Firewire drive, USB drive, SD, MMC, XD, Compact Flash, Memory Stick, and the like. In the preferred embodiment of the subject application, the document processing device 104 further includes an associated user interface 106, such as a touchscreen, LCD display, touch-panel, alpha-numeric keypad, or the like, via which an associated user is able to interact directly with the document processing device 104. In accordance with the preferred embodiment of the subject application, the user interface 106 is advantageously used to communicate information to the associated user and receive selections from the associated user. The skilled artisan will appreciate that the user interface 106 comprises various components, suitably adapted to present data to the associated user, as are known in the art. In accordance with one embodiment of the subject application, the user interface 106 comprises a display, suitably adapted to display one or more graphical elements, text data, images, or the like, to an associated user, receive input from the associated user, and communicate the same to a backend component, such as the controller 108, as explained in greater detail below. Preferably, the document processing device 104 is communicatively coupled to the computer network 102 via a communications link 112. As will be understood by those skilled in the art, suitable communications links include, for example and without limitation, WiMax, 802.11a, 802.11b, 802.11g, 802.11(x), Bluetooth, the public switched telephone network, a proprietary communications network, infrared, optical, or any other suitable wired or wireless data transmission communications known in the art. The functioning of the document processing device 104 will be better understood in conjunction with the block diagrams illustrated in
In accordance with one embodiment of the subject application, the document processing device 104 incorporates a backend component, designated as the controller 108, suitably adapted to facilitate the operations of the document processing device 104, as will be understood by those skilled in the art. Preferably, the controller 108 is embodied as hardware, software, or any suitable combination thereof, configured to control the operations of the associated document processing device 104, facilitate the display of images via the user interface 106, direct the manipulation of electronic image data, and the like. For purposes of explanation, the controller 108 is used to refer to any myriad of components associated with the document processing device 104, including hardware, software, or combinations thereof, functioning to perform, cause to be performed, control, or otherwise direct the methodologies described hereinafter. It will be understood by those skilled in the art that the methodologies described with respect to the controller 108 is capable of being performed by any general purpose computing system, known in the art, and thus the controller 108 is representative of such general computing devices and is intended as such when used hereinafter. Furthermore, the use of the controller 108 hereinafter is for the example embodiment only, and other embodiments, which will be apparent to one skilled in the art, are capable of employing the system and method for image contrast enhancement. The functioning of the controller 108 will better be understood in conjunction with the block diagrams illustrated in
Communicatively coupled to the document processing device 104 is a data storage device 110. In accordance with the one embodiment of the subject application, the data storage device 110 is any mass storage device known in the art including, for example and without limitation, magnetic storage drives, a hard disk drive, optical storage devices, flash memory devices, or any suitable combination thereof. In one embodiment, the data storage device 110 is suitably adapted to store scanned image data, color measurement data, color calibration data, or the like. It will be appreciated by those skilled in the art that while illustrated in
Depicted in
Turning now to
Also included in the device 200 is random access memory 206, suitably formed of dynamic random access memory, static random access memory, or any other suitable, addressable memory system. Random access memory provides a storage area for data instructions associated with applications and data handling accomplished by the processor 202.
A storage interface 208 suitably provides a mechanism for volatile, bulk or long term storage of data associated with the device 200. The storage interface 208 suitably uses bulk storage, such as any suitable addressable or serial storage, such as a disk, optical, tape drive and the like as shown as 216, as well as any suitable storage medium as will be appreciated by one of ordinary skill in the art.
A network interface subsystem 210 suitably routes input and output from an associated network allowing the device 200 to communicate to other devices. The network interface subsystem 210 suitably interfaces with one or more connections with external devices to the device 200. By way of example, illustrated is at least one network interface card 214 for data communication with fixed or wired networks, such as Ethernet, token ring, and the like, and a wireless interface 218, suitably adapted for wireless communication via means such as WiFi, WiMax, wireless modem, cellular network, or any suitable wireless communication system. It is to be appreciated however, that the network interface subsystem suitably utilizes any physical or non-physical data transfer layer or protocol layer as will be appreciated by one of ordinary skill in the art. In the illustration, the network interface card 214 is interconnected for data interchange via a physical network 220, suitably comprised of a local area network, wide area network, or a combination thereof.
Data communication between the processor 202, read only memory 204, random access memory 206, storage interface 208 and the network subsystem 210 is suitably accomplished via a bus data transfer mechanism, such as illustrated by the bus 212.
Suitable executable instructions on the device 200 facilitate communication with a plurality of external devices, such as workstations, document processing devices, other servers, or the like. While, in operation, a typical device operates autonomously, it is to be appreciated that direct control by a local user is sometimes desirable, and is suitably accomplished via an optional input/output interface 222 to a user input/output panel 224 as will be appreciated by one of ordinary skill in the art.
Also in data communication with the bus 212 are interfaces to one or more document processing engines. In the illustrated embodiment, printer interface 226, copier interface 228, scanner interface 230, and facsimile interface 232 facilitate communication with printer engine 234, copier engine 236, scanner engine 238, and facsimile engine 240, respectively. It is to be appreciated that the device 200 suitably accomplishes one or more document processing functions. Systems accomplishing more than one document processing operation are commonly referred to as multifunction peripherals or multifunction devices.
Turning now to
The document processing engine 302 suitably includes a print engine 304, facsimile engine 306, scanner engine 308 and console panel 310. The print engine 304 allows for output of physical documents representative of an electronic document communicated to the processing device 300. The facsimile engine 306 suitably communicates to or from external facsimile devices via a device, such as a fax modem.
The scanner engine 308 suitably functions to receive hard copy documents and in turn image data corresponding thereto. A suitable user interface, such as the console panel 310, suitably allows for input of instructions and display of information to an associated user. It will be appreciated that the scanner engine 308 is suitably used in connection with input of tangible documents into electronic form in bitmapped, vector, or page description language format, and is also suitably configured for optical character recognition. Tangible document scanning also suitably functions to facilitate facsimile output thereof.
In the illustration of
The document processing engine 302 is suitably in data communication with one or more device drivers 314, which device drivers allow for data interchange from the document processing engine 302 to one or more physical devices to accomplish the actual document processing operations. Such document processing operations include one or more of printing via driver 318, facsimile communication via driver 320, scanning via driver 322 and a user interface functions via driver 324. It will be appreciated that these various devices are integrated with one or more corresponding engines associated with the document processing engine 302. It is to be appreciated that any set or subset of document processing operations are contemplated herein. Document processors which include a plurality of available document processing options are referred to as multi-function peripherals.
Turning now to
Also included in the controller 400 is random access memory 406, suitably formed of dynamic random access memory, static random access memory, or any other suitable, addressable and writable memory system. Random access memory provides a storage area for data instructions associated with applications and data handling accomplished by processor 402.
A storage interface 408 suitably provides a mechanism for non-volatile, bulk or long term storage of data associated with the controller 400. The storage interface 408 suitably uses bulk storage, such as any suitable addressable or serial storage, such as a disk, optical, tape drive and the like as shown as 416, as well as any suitable storage medium as will be appreciated by one of ordinary skill in the art.
A network interface subsystem 410 suitably routes input and output from an associated network allowing the controller 400 to communicate to other devices. The network interface subsystem 410 suitably interfaces with one or more connections with external devices to the device 400. By way of example, illustrated is at least one network interface card 414 for data communication with fixed or wired networks, such as Ethernet, token ring, and the like, and a wireless interface 418, suitably adapted for wireless communication via means such as WiFi, WiMax, wireless modem, cellular network, or any suitable wireless communication system. It is to be appreciated however, that the network interface subsystem suitably utilizes any physical or non-physical data transfer layer or protocol layer as will be appreciated by one of ordinary skill in the art. In the illustration, the network interface 414 is interconnected for data interchange via a physical network 420, suitably comprised of a local area network, wide area network, or a combination thereof.
Data communication between the processor 402, read only memory 404, random access memory 406, storage interface 408 and the network interface subsystem 410 is suitably accomplished via a bus data transfer mechanism, such as illustrated by bus 412.
Also in data communication with the bus 412 is a document processor interface 422. The document processor interface 422 suitably provides connection with hardware 432 to perform one or more document processing operations. Such operations include copying accomplished via copy hardware 424, scanning accomplished via scan hardware 426, printing accomplished via print hardware 428, and facsimile communication accomplished via facsimile hardware 430. It is to be appreciated that the controller 400 suitably operates any or all of the aforementioned document processing operations. Systems accomplishing more than one document processing operation are commonly referred to as multifunction peripherals or multifunction devices.
Functionality of the subject system 100 is accomplished on a suitable document processing device, such as the document processing device 104, which includes the controller 400 of
In a preferred embodiment, the engine 502 allows for printing operations, copy operations, facsimile operations and scanning operations. This functionality is frequently associated with multi-function peripherals, which have become a document processing peripheral of choice in the industry. It will be appreciated, however, that the subject controller does not have to have all such capabilities. Controllers are also advantageously employed in dedicated or more limited purposes document processing devices that perform one or more of the document processing operations listed above.
The engine 502 is suitably interfaced to a user interface panel 510, which panel allows for a user or administrator to access functionality controlled by the engine 502. Access is suitably enabled via an interface local to the controller, or remotely via a remote thin or thick client.
The engine 502 is in data communication with the print function 504, facsimile function 506, and scan function 508. These functions facilitate the actual operation of printing, facsimile transmission and reception, and document scanning for use in securing document images for copying or generating electronic versions.
A job queue 512 is suitably in data communication with the print function 504, facsimile function 506, and scan function 508. It will be appreciated that various image forms, such as bit map, page description language or vector format, and the like, are suitably relayed from the scan function 508 for subsequent handling via the job queue 512.
The job queue 512 is also in data communication with network services 514. In a preferred embodiment, job control, status data, or electronic document data is exchanged between the job queue 512 and the network services 514. Thus, suitable interface is provided for network based access to the controller function 500 via client side network services 520, which is any suitable thin or thick client. In the preferred embodiment, the web services access is suitably accomplished via a hypertext transfer protocol, file transfer protocol, uniform data diagram protocol, or any other suitable exchange mechanism. The network services 514 also advantageously supplies data interchange with client side services 520 for communication via FTP, electronic mail, TELNET, or the like. Thus, the controller function 500 facilitates output or receipt of electronic document and user information via various network access mechanisms.
The job queue 512 is also advantageously placed in data communication with an image processor 516. The image processor 516 is suitably a raster image process, page description language interpreter or any suitable mechanism for interchange of an electronic document to a format better suited for interchange with device functions such as print 504, facsimile 506 or scan 508.
Finally, the job queue 512 is in data communication with a parser 518, which parser suitably functions to receive print job language files from an external device, such as client device services 522. The client device services 522 suitably include printing, facsimile transmission, or other suitable input of an electronic document for which handling by the controller function 500 is advantageous. The parser 518 functions to interpret a received electronic document file and relay it to the job queue 512 for handling in connection with the afore-described functionality and components.
Turning now to
The read only memory 604 suitably includes firmware, such as static data or fixed instructions, such as BIOS, system functions, configuration data, and other routines used for operation of the workstation 600 via CPU 602.
The random access memory 606 provides a storage area for data and instructions associated with applications and data handling accomplished by the processor 602.
The display interface 608 receives data or instructions from other components on the bus 614, which data is specific to generating a display to facilitate a user interface. The display interface 608 suitably provides output to a display terminal 628, suitably a video display device such as a monitor, LCD, plasma, or any other suitable visual output device as will be appreciated by one of ordinary skill in the art.
The storage interface 610 suitably provides a mechanism for non-volatile, bulk or long term storage of data or instructions in the workstation 600. The storage interface 610 suitably uses a storage mechanism, such as storage 618, suitably comprised of a disk, tape, CD, DVD, or other relatively higher capacity addressable or serial storage medium.
The network interface 612 suitably communicates to at least one other network interface, shown as network interface 620, such as a network interface card, and wireless network interface 630, such as a WiFi wireless network card. It will be appreciated that by one of ordinary skill in the art that a suitable network interface is comprised of both physical and protocol layers and is suitably any wired system, such as Ethernet, token ring, or any other wide area or local area network communication system, or wireless system, such as WiFi, WiMax, or any other suitable wireless network system, as will be appreciated by one of ordinary skill in the art. In the illustration, the network interface 620 is interconnected for data interchange via a physical network 632, suitably comprised of a local area network, wide area network, or a combination thereof.
An input/output interface 616 in data communication with the bus 614 is suitably connected with an input device 622, such as a keyboard or the like. The input/output interface 616 also suitably provides data output to a peripheral interface 624, such as a USB, universal serial bus output, SCSI, Firewire (IEEE 1394) output, or any other interface as may be appropriate for a selected application. Finally, the input/output interface 616 is suitably in data communication with a pointing device interface 626 for connection with devices, such as a mouse, light pen, touch screen, or the like.
Turning now to
Referring now to
The skilled artisan will appreciate that the subject system 100 and components described above with respect to
At step 904, the processor generates histogram data corresponding to the received image data. It will be appreciated by those skilled in the art that such generation includes the calculation of the histogram from the received encoded image. The acceptability of the received image data is then determined at step 906 in accordance with a comparison that is performed of the histogram data and at least one preselected threshold value. At step 908, a contrast adjustment is performed on the input image based upon the histogram data. Preferably, the contrast adjustment includes a white stretch, a black stretch, and a contrast stretch.
Referring now to
A determination is then made at step 1008 whether the input image is acceptable for image contrast enhancement in accordance with one embodiment of the subject application. In the event that the input image is not acceptable, i.e. the image is an artistic, fog, dark, or bright scene, operations with respect to
At step 1012, intermediate image data is generated in accordance with the determined white stretch and black stretch. According to one example embodiment, and as illustrated more fully below, the intermediate image data is generated by application of the white stretch amount plus the black stretch amount to the input image data. The intermediate image data is then compared at step 1014 to a contrast threshold. That is, a calculated contrast value associated with the intermediate image data is tested against a predetermined contrast threshold. In accordance with one example embodiment of the subject application, the contrast threshold corresponds to the contrast measurement associated with the intermediate image. For example purposes only, the contrast measurement of the subject application corresponds to the variance of the standard deviation from the brightness average of the input image. In such an example embodiment, the threshold corresponds to an upper bound contrast, e.g. illustrated more fully in
A determination is then made at step 1016 whether the intermediate image data exceeds the predetermined contrast threshold. When the calculated contrast of the intermediate image exceeds the contrast threshold, flow proceeds to step 1018, whereupon the intermediate image data is output for further processing by the document processing device 104, the user device 114, or the like. Thereafter, operations with respect to
At step 1022, contrast stretch is performed based upon a first and a second boundary value and a quadratic interpolation between a minimum curvature factor and a maximum curvature factor. Preferably, at least one preselected boundary value, as discussed below, is used in the contrast stretch of step 1022. Thereafter, at step 1024, contrast adjustment is performed on the input image data using the white, black, and contrast stretch. The contrast enhanced image is then output for further processing at step 1026, whereupon operations with respect to
The preceding example methodologies will be better understood in conjunction with the illustrations of
According to one embodiment of the subject application, image contrast enhancement is capable of being restricted as inappropriate for application to some specific scenes, e.g. illustrated in
As will be understood by those skilled in the art, the subject application adopts a textbook definition of the contrast measurement as the variance of the standard deviation from the brightness average of the input image. Image contrast enhancement, according to one embodiment of the subject application, is achieved by global brightness enhancement (White Stretch 1300), global darkness enhancement (Black Stretch 1302) and contrast enhancement (Contrast Stretch with S-Curve 1304) as illustrated in
According to one example embodiment of the subject application, the amount of White Stretch (WS) is determined by the length of the long tail of the image histogram, and the amount of Black Stretch (BS) is determined by the length of the long ramp of the image histogram. After BS and WS are determined, black stretch with BS amount plus white stretch with WS amount (BS+WS) is applied to the input image M to obtain the resulting image M′. If M′ is not a low contrast image, e.g., the contrast measurement of the image M′>Upper Bound (0.06), then the input M′ is output and operations cease. Otherwise, Contrast Stretch (CS) with S-Curve is applied to the image M′. Preferably, the Curvature Factor F is calculated based on the contrast measurement of the image M′.
After the Curvature Factors are determined, the location of the Inflection Point is obtained by an exhaustive search. For example, a plurality of proposed inflection points, such as 10 proposed inflection points, may be defined at equal intervals spanning the intermediate image data (the data between the white stretch and black stretch regions). A tonal mapping TRC may be defined for each proposed inflection point using the previously defined Curvature Factors. Each TRC may be applied to the image and the resulting image contrast of each remapped image may be determined. The proposed inflection point that provides the highest image contrast is then selected as the Inflection Point. Other search strategies may be used to determine the Inflection Point. After the Curvature Factor1, Curvature Factor2, and the Inflection Point are determined, black stretch with BS amount plus white stretch with WS amount plus contrast stretch (CS) with Curvature Factor1, Curvature Factor2, and the Inflection Point (BS+WS+CS) is applied to the input image M to obtain the resulting image M″. Thereafter, the image M′ is output and the methodology of the preceding example embodiment terminates, as will be appreciated by those skilled in the art.
The preceding example embodiment is suitably illustrated in the flowchart 1700 of
The foregoing description of a preferred embodiment of the subject application has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the subject application to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the subject application and its practical application to thereby enable one of ordinary skill in the art to use the subject application in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the subject application as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/258,705, filed on Nov. 6, 2009, titled “AUTOMATIC CONTRAST ENHANCEMENT”, the entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61258705 | Nov 2009 | US |
