Patent Application
20100238461
The invention relates generally to the field of printing systems. More particularly, the invention relates to selecting ink profiles in a color printing system.
Growth in color management has resulted in an increase in software packages that are used to generate International Color Consortium (ICC) profiles. ICC profiles describe color attributes of a particular device or viewing requirement by defining a mapping between a source or target color space and a profile connection space (PCS), such as either CIELAB (L*a*b*) or CIEXYZ.
Typically, a printer operator uses a graphical user interface to select a particular color profile for one or more print jobs. However, operators often select an incorrect ICC profile for a paper or ink set that has been loaded since each ICC profile is valid only for a given set of printing conditions. Improper selection of an ICC profile results in poor print quality of a print job. Thus, operators must often undergo a time consuming process of becoming trained as to how to properly select ICC profiles for print jobs.
Accordingly, a mechanism for automatically selecting ICC profiles is desired.
In one embodiment, a printing system is disclosed. The printing system includes a print system to print data received at the printing system, a color image recording device to measure one or more control patches from the data printed at the print system and a control unit to compare measurement data from the control patches to data from available International Color Consortium (ICC) profiles to select an appropriate ICC profile corresponding the control patches.
Another embodiment discloses a method of a color image recording device measuring one or more control patches from print data, a control unit comparing measurement data from the control patches to data from available International Color Consortium (ICC) profiles and the control unit selecting an ICC profile having data values closest to values of the measurement data.
A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which:
A mechanism for automatically selecting ICC profile is described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the present invention.
Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
Network 106 may be a local area network (LAN) or any other network over which print requests may be submitted to a remote printer or print server. Communications link 104 may be in the form of a network adapter, docking station, or the like, and supports communications between data processing system 102 and network 106 employing a network communications protocol such as Ethernet, the AS/400 Network, or the like.
According to one embodiment, network 106 includes a print server/printer 108 serving print requests over network 106 received via communications link 110 between print server/printer 108 and network 106. The operating system on data processing system 102 is capable of selecting print server/printer 108 and submitting requests for services to print server/printer 108 over network 106. Print server/printer 108 includes a print queue for print jobs requested by remote data processing systems 102. Further, print server/printer 108 includes a control unit to perform operations associated with printing a request.
Although described as incorporated within the same entity, other embodiments may include the print server and the printer as being physically separate components. Therefore, the data processing system network 100 depicted in
Printer 200 also includes color lookup tables (CLUTs) 220. CLUTs 220 support ICC profiles used in printer 200 to enable the use of different color transforms, where each transform is tailored for a different effect. According to one embodiment, each profile includes up to 6 CLUT's, three for input (AtoB tables, which convert from device space to PCS, and three for output (BtoA tables, that convert from PCS to device space).
Printer 200 includes a print system 230 that physically applies print job data on a print medium.
Print head 350 includes a printing element that applies ink to a print medium. According to one embodiment, print head 350 is a wide-array inkjet print head that employs multiple sets of nozzles that are implemented to spray droplets of ink onto a sheet of paper in order to execute a print job. However, print head 350 may include other types of ink jet print heads, as well as a moving print head design.
Referring back to
Control unit 250 is included with in printer 200 to control the operation of print system 230. In addition, control unit receives the measurement data from color image recording device 240. In such an embodiment, control unit 250 converts the measured results from the device space (e.g., cyan, magenta, yellow, and black (CMYK)) to the PCS space (e.g., L*a*b*). The measured results are then compared to available ICC profiles to find the best profile for the given response of the control patches.
At processing block 420, one or more control patches printed on the test page is measured by color image recording device 240. At processing block 430, the measured control patch data is converted from CMYK to L*a*b* data. At processing bock 440, CMYK values from the print data used to generate the test patch is pushed through the AtoB tables of the CLUTs 220 to generate L*a*b* values for each available ICC profile. At processing block 450, the measured L*a*b* data values are compared to the generated L*a*b* values.
At processing block 460, control unit 250 selects the ICC profile having the generated L*a*b* values that are closest to the measured L*a*b* values. According to one embodiment, a mean Delta-E (dE) of each of the generated L*a*b* values, where the ICC profile corresponding to the lowest metric is selected. dE is a difference metric having a single number that represents the distance between two colors. A dE of 1.0 is the smallest color difference the human eye can see. Thus, a dE less than 1.0 is imperceptible dE. However in other embodiments, other types of difference metrics may be implemented to select the ICC profile having the generated L*a*b* values that are closest to the measured L*a*b* values.
Once the closest ICC profile is selected, printer 200 is available to print the highest quality print job possible for the current settings and paper. In a further embodiment, the GUI prompts the operator to generate a new ICC profile if none of the ICC profiles of L*a*b* values are within a predefined range of the measured L*a*b* values.
The above-described ICC profile selection mechanism reduces errors associated with incorrectly selected ICC profiles, as well as reducing set up time to select the best existing profile.
Embodiments of the invention may include various steps as set forth above. The steps may be embodied in machine-executable instructions. The instructions can be used to cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components.
Elements of the present invention may also be provided as a machine-readable medium for storing the machine-executable instructions. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, propagation media or other type of media/machine-readable medium suitable for storing electronic instructions. For example, the present invention may be downloaded as a computer program which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) via a communication link (e.g., a modem or network connection).
Whereas many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that any particular embodiment shown and described by way of illustration is in no way intended to be considered limiting. Therefore, references to details of various embodiments are not intended to limit the scope of the claims, which in themselves recite only those features regarded as essential to the invention.
