GB2409122A

GB2409122A - Automatic generation and use of colour profiles for printers by locating a spectrophotometer within the printer

Info

Publication number: GB2409122A
Application number: GB0325860A
Authority: GB
Inventors: Timothy John Freeman; Nadia Pariset
Original assignee: Canon Europa NV
Current assignee: Canon Europa NV
Priority date: 2003-11-05
Filing date: 2003-11-05
Publication date: 2005-06-15
Anticipated expiration: 2023-11-05
Also published as: GB2409122B; GB0325860D0

Abstract

A method for generating a colour performance profile, such as an ICC profile, that describes the colour performance of a printer is described. The method comprises printing a colour test image using the printer, measuring the colour profile of the printed image using a spectrophotometer and generating the colour performance profile from the outputs of said spectrophotometer. A printer for performing the method is also described. The spectrophotometer is located within the printer and may, for example, form part of a buffer unit of the printer. In use, print media is arranged to pass the spectrophotometer sufficiently slowly so that the spectrophotometer has time to measure the said colour profile.

Description

- 1 - 2409122 Automatic Generation and Use of Colour Profiles For Printers

The present invention relates to the generation and use of S colour profiles, such as International Color Consortium (ICC) profiles, for devices such as printers, photocopiers and scanners.

Traditional office photocopiers, scanners and printers have lO developed considerably in recent years. Typically, scanners, printers and photocopiers were separate, stand- alone devices. Multi-purpose devices, termed Multi- Functional Products (MFPs), have been developed in recent times that are typically able to print, scan and photocopy documents as well as transfer files, such as scanned images, over a network.

Figure l shows a network consisting of an MFP 2 connected to a file server 4 and an E-Mail client 6 over a local area network (LAN) 8. LAN 8 is also connected to the Internet lO. In addition to being connected to local file server 4 and local Email client 6 via LAN 8, MFP 2 is also connected to remote file server 12 and remote Email client 14 via the Internet lO. Documents can be sent over a network consisting of LAN 8 or LAN 8 and the Internet lO to MFP 2 for printing: similarly, scanned files can be transmitted from MFP 2 over the network.

In addition to the increased functionality of an MFP when compared with traditional stand-alone black-and-white printers, photocopiers and scanners, many MFPs are able to print, copy and scan colour images.

Figure 2 shows a simple graphic arts workflow. An image is scanned using an MFP at step 16. The scanned image is then - 2 placed in a document 18, such as that generated using a word processing package. The document 18 includes one or more colour images that have been scanned in step 16 as RGB (red green blue) images. The document 18 may be used as a web-based document and displayed on a terminal as an RGB document, as shown at step 20. Alternatively, the document may be printed on a CMYK (cyan, Magenta, yellow, black) printer. A conversion between the RGB colour space and the CMYK colour space may take place before printing (as shown l0 at step 22 and 24) or at the printer (as shown at step 26).

It is clear that different RGB scanners, or even different scanners of the same manufacturer and model, are likely to perform differently and therefore produce different RGB images if they were to scan the same document. Moreover, the performance of any particular scanner will change over time, as discussed below.

Thus, as a result of the varying colour performances of the scanner, two scanned images of the same original may look different when viewed on a display (step 20 of Figure 2) or when printed (steps 24 or 26 of Figure 2) despite being scanned on the same scanner. Accordingly, the colour reproduction in the example workflow of Figure 2 is dependent on the performance of the scanner.

If the document 18 is printed, similar problems exist at the printer since, as with scanners, the printer output can vary according to a variety of factors. Accordingly, the colours of the printed image (steps 24 or 26 of Figure 2) depend on the performance of both the scanner and the printer.

In a similar manner, the colour performance of a display device used to display the ROB document (step 20 of Figure 2) will vary from device to device and with time.

There are a number of factors that are known to effect colour representation. Environmental factors, such as humidity and temperature, effect the performance of MFPs.

The performance of the various components of MFPs, such as scanner lamps, change over time as they wear; this has an impact of the colour representation of both scanners and printers. The media from which a scanned image is derived or onto which a printed image is printed has an impact on the colour that is perceived. For example, the same image, printed by the same printer, on similar paper from different batches, may look different and an image scanned from matt paper and subsequently printed may look different from that image scanned from glossy paper and subsequently printed. Further, the toner level and quality will have an impact on the colours produced.

It is therefore clear that the colours of a printed image that is derived from a scanned image or of a displayed image derived from that scanned image can vary significantly, and variably, from the colours of the original image.

Scientific colour measurement can be based on the response of the human eye to red, green and blue light. The Commission Internationale de l'Eclairage (CIE) has established models for the response of the average human eye. A standard developed by CIE based on this principle is known as the CIE X,Y,Z model.

Alternative models to the CIE X,Y,Z model include those based on the opponent-colours theory, which suggests that - 4 - the human eye compares red response with green response to generate a red- to-green colour dimension (known by the symbol "a") and compares green responses with blue responses to generate a green-to-blue colour dimension (known by the symbol "b"). A 1976 CIE standard based on the a- and lo- type scales identified above and an L-scale (concerning the lightness) was adopted in the CIE 1976 L*a*b scale (or "CIELAB" for short). The CIELAB definition for lightness is based on the CIEXYZ standard, which is a tristimulus measurement of colour. The lightness value L is a number between O and 100, with white being 0, black and perfect grey 50.

An approach to defining a colour management standard has been developed by the International Color Consortium (ICC) of 1899 Preston White Drive, Reston VA 20191 USA (www.icc.org).

The ICC promotes a standard colour profile (the "ICC Profile"). These profiles describe the maximum achievable colour capability of a given device (typically the profiles will describe the colour capability of a device using the CIELAB colour space). The information within the profiles can then be used to assist a transformation between the colour space of a device and the common colour space known, in the ICC system, as the profile connection space (PCS).

The PCS describes an ideal reflection print viewed in a graphic arts viewing environment (D50 white point). (The D50 white point refers to a colour temperature of 5000 Kelvin. Natural daylight in normally quoted as D65 (or 6500 Kelvin). D50 is defined as the graphic arts standard in ISO13655.) The ICC system includes a number of profiles, which can be categorized as input (or source) profiles and output (or - 5 destination) profiles. For example, a profile associated with a monitor would be an output/destination profile while a profile associated with a scanner would be an input/source profile.

Transformer algorithms utilise the source and destination profiles in conjunction with the PCS to modify the image data to achieve the best possible match on the output device. The actual transformation of the data will be performed by a "colour engine"; these typically exist within applications of an operating system. Apple_ provide Colorsyncwithin their operating system. Microsoft_ provide ICM within their operating system. Adobe_ provide the Adobe Colour Engine (ACE) with some of their applications.

These colour engines are hereinafter referred to as Colour Management Modules (CMMs).

A source profile is a measure of the colour performance of the relevant source device. A destination profile is a measure of the colour performance of the relevant destination device. By transforming data according to the attributes of the source and destination devices that process the data, a colour image that is scanned and then printed (or displayed) should be a good reproduction of the original colours, regardless of the scanner and printer/display used. This is because the variations introduced by the devices are known from the source/destination profiles and can therefore be compensated for by the CMM.

The term "data transformer" is used herein to mean a combination of the Colour Management Module (CMM) and the Profile Connection Space. In terms of the actual data transformation it is the CMM that is performing the calculations. However, it uses the framework of the ICC - 6 specification to do this and the illustrative figures can also be viewed in terms of the underlying theory - Profile Connection Spaces.

Figure 3 shows an approach to alleviating the problem of the colours of images appearing differently when printed on different printers. The system of Figure 3 includes a CMYK source 28, CMYK printer A 30 and CMYK printer B 32. For the reasons discussed above, if data from CYMK source 28 is sent to CMYK printers A and B. the colours of the printed images will be different. It follows that, in order to get similar colour results from the two printers, the data that is sent to each printer must in fact be different.

In the system of Figure 3, the CYMK data from CMYK source 28 is passed through data transformer 34. Data transformer 34 is arranged to take the values sent to CYMK Printer A 30 and convert them into corresponding values that reproduce those colours on CMYK printer B 32. (Of course, the CMYK source could be replaced with an RGB source.) The same principle can be applied to scanners, as shown in Figure 4. The system of Figure 4 comprises RGB scanner A 36, RGB scanner B 38, RGB display 40 and transformers 42 and 44. Transformer 42 transforms the RGB data from RGB scanner A 36 that is passed to RGB display 40: transformer 44 transforms the RGB data from RGB scanner B 38 that is passed to the RGB display.

Since scanners 36 and 38 will have different colour performances, if an image scanned on each of those scanners is to look the same when the scanned images are displayed on RGB display 40, then the transformers 42 and 44 must be different. Clearly, the transformations performed by transformers 42 and 44 must be dependent on the performances of scanners 36 and 38 respectively.

Only one data transformer 34 is provided in the printer system of Figure 3, whereas two data transformers 42, 44 are provided for the scanner system of Figure 4. In the system of Figure 3, printer A 30 is a reference printer for which no data transformation is required, thus all other printers in the system (just printer B 32 in the example of Figure 3) are adjusted according to the reference printer.

Of course, the system of Figure 3 could be adapted to provide two data transformers, one for each of the two printers. Similarly, in the system of Figure 4, one of the scanners could be deemed a reference scanner and a single data transformer provided for the other scanner.

One of the major drawbacks of the ICC system is in the current implementation which necessitates the individual manual creation and manual attachment of the relevant profiles for each device in the workflow. It follows that the more devices that are involved, the more profiles there are that must be both created and managed.

To generate an ICC profile for a scanner, a test chart (such as an ANSI IT8.7/2 chart) is placed on the scanner and scanned in the normal way. An example of a test chart, indicated generally by the reference numeral 84, is shown in Figure 5 (albeit in black and white). Profile creation software is then used to take the scanned image and convert it into the finished profile. This requires processing to determine, amongst other things, where the corner points of the scanned image are. Two well-known examples of profile creation software are Typemakers Colourblind and Gretag- Macbeths ProfileMaker. - 8

In a similar way, a destination profile for a printer can be generated by printing a "patch page" similar to the test chart of Figure 5 on the printer and then taking a series of measurements of the printed colours using a spectrophotometer to measure the spectral response of reflected light to build an ICC compliant profile.

The inventor has noticed that this process suffers from a number of problems, including: The user must have a spectrophotometer, workstation for running the relevant software and the output device at the same location. The service may be delivered remotely, but this leaves the user vulnerable to missing out on the main benefits of the system.

The destination profile requires regular updating.

Errors may be introduced where a number of users use the system, especially when some of those users lack experience with using the destination profile generation software.

Multiple profiles may need to be generated for the same printer, such as different profiles for different printing media. Each of these profiles may require regular updating.

The necessity to have access to all of the appropriate profiles when needed and to have appropriate descriptive information to select the correct profile can lead to errors, as well as slowing down the process.

The process of creating a printer profile is more complex than with a scanner. There are numerous factors that must normally be considered. First, how many patches should be measured? Most applications allow for different numbers of patches to be printed: in general the more patches that are measured the more accurate the resulting profile. Second, which chart should they use to generate the profile? - 9 IT8/7.3 and ECI2002 are two examples but there are a number of other charts that could be used. Once the type of chart and the number of patches has been decided then the user could still face a number of choices such as the size of the profile that they wish to generate (again, bigger is generally more accurate but may not be worth the extra effort). Also, the rendering intent is an issue: the user must typically choose between Perceptual, Absolute, Relative and Saturation. The user may also then have to ]0 decide whether they wish to use GCR or UCR in the profile and to what degree as well as deciding on the viewing white point.

It is an object of the present invention to address at least some of the problems outlined above.

The present invention provides a method of generating a colour performance profile that describes the colour performance of a printer, the method comprising the steps of: printing a colour test image using said printer; measuring the colour profile of the printed image using a spectrophotometer; and generating said colour performance profile from the outputs of said spectrophotometer, wherein said spectrophotometer is located within the printer and, in use, print media is arranged to pass the spectrophotometer sufficiently slowly that the spectrophotometer has time to measure the said colour profile.

The present invention also provides a printer comprising a spectrophotometer for measuring the colour profile of a colour test image printed by said printer and means for generating a colour performance profile of said printer - 10 from said profile measurement, wherein print media is arranged to pass the spectrophotometer sufficiently slowly that the spectrophotometer has time to measure the said colour profile. s

Incorporating the spectrophotometer within the printer leads to the potential problem of the print media (usually paper) moving too quickly for the spectrophotometer to accurately measure the colour profile of the printed test chart. This is addressed in the present invention by controlling the speed of flow of the print media.

The spectrophotometer may be part of a buffer unit of said printer. The buffer unit may be located between a main printer body and a finishing unit of the printer. Further, the main printer body may comprise a printing unit and a fixing unit, wherein the buffer is located downstream of said fixing unit. It is known to use a buffer unit to control the rate of flow of print media being passed from the main printer body to the finisher unit. Accordingly, such a buffer unit can be adapted to control the flow of print media such that the spectrophotometer has time to measure the colour profile of the printed test chart.

The printer may comprise a main printer body comprising a printing unit and a fixing unit, wherein the spectrophotometer is located downstream of the fixing unit.

In one embodiment of the invention, the speed at which the print media exits the fixing unit is controlled so that it is at an appropriate speed for the spectrophotometer to measure the said colour profile.

It is known to provide a main printer body having a printing unit and a fixing unit, with toner being applied - 11 in the printing unit and fixed to the print media in the fixing unit. In such an arrangement, the rate of flow of print media in the fixing unit may be controlled depending on the fixing time required, which may vary according to the characteristics of the media. Accordingly, the fixing unit can be adapted to control the flow of print media such that the spectrophotometer has time to measure the colour profile of the printed test chart.

In one form of the invention, the spectrophotometer has a single head that substantially spans the width of a printed image. In another form of the invention, a plurality of spectrophotometers are used, said plurality of spectrophotometers substantially spanning the width of a printed image.

The colour performance profile may be compared with the profile of a reference file, wherein said colour performance profile becomes the reference file if the colour performance profile differs from the reference file by more than a predetermined amount. The colour performance profile and the reference profile may be compared by determining the delta E difference between those profiles.

The colour performance profile generation may be initiated in one of many ways, such as, in response to a request from a user, in response to detection of an event that is relevant to said profile (such as maintenance of the printer), each time the printer is turned on, when a predetermined period has elapsed since the colour performance profile generation was last initiated, periodically, according to a programmed schedule, when a predetermined number of pages have been printed since the colour performance profile generation was last initiated, - 12 whenever a new printing media is used, whenever a print job exceeds a predetermined size, whenever the printing finishing options exceed a predetermined quality setting, and on detection of a significant change in the printing conditions. Any combination of the options listed above may apply in any particular embodiment of the invention.

The colour performance profile may be an ICC profile. The colour test image is an ANSI IT8.7/2 test chart; other suitable test charts are known to the skilled person.

The colour test image may be electronically stored within a memory of said printer. The colour performance profile may be electronically stored within a memory of said printer.

A user may be given access to said colour performance profile.

The printer may comprise a network controller for receiving print instructions from one or more sources on a network and converting said instructions into raster image data for printing on said printer.

The present invention also provides a device comprising a printer as described above and further comprising a scanner. The device may also have a photocopying function.

The present invention also provides a computer program product arranged, when executed, to generate a colour performance profile of a printer, wherein the colour performance profile is determined by printing a colour test image, measuring the colour performance profile of the printed colour test image using a spectrophotometer, and generating the colour performance profile from the outputs of the spectrophotometer, wherein said spectrophotometer is - 13 located within the printer and print media is arranged to pass the spectrophotometer sufficiently slowly that the spectrophotometer has time to measure the said colour profile.

By way of example only, embodiments of the present invention will now be described with reference to the accompanying drawings, of which: FIGURE l shows a network including a Multi Functional Product (MFP); FIGURE 2 is a flow chart showing an example of a simple graphic arts workflow; FIGURE 3 shows a system for controlling the colour reproduction of printed CYMK images; FIGURE 4 shows a system for controlling the colour reproduction of scanned ROB images; FIGURE 5 shows a typical colour test chart that may be used with the present invention; FIGURE 6 shows a printing arrangement that can be used in accordance with the present invention; FIGURE 7 shows a series arrangement of spectrophotometers in accordance with an aspect of the present invention; FIGURE 8 shows an alternative spectrophotometer arrangement in accordance with another aspect of the present invention; and FIGURE 9 is a flow chart showing an example of a destination profile generation process in accordance with an embodiment of the present invention.

As discussed above, a destination profile for a printer can be generated by printing a "patch page" on the printer and then taking a series of measurements of the printed colours - 14 using a spectrophotometer to build an ICC compliant profile.

Figure 6 shows a printer arrangement consisting of a network controller 124 and a printer indicated generally by the reference numeral 126. The network controller 124 receives print instructions from a variety of sources on a network. The network controller 124 converts incoming data into raster image data for printing on printer 126. The l0 network controller 124 may be embedded within the printer 126.

Printer 126 consists of a main printer body indicated generally by the reference numeral 128 and a finisher unit 132. The main printer body 128 consists of a printing unit 129 and a fixing unit 130. The different colour toners are applied in the printing unit 129 utilising a single drum or four drum mechanism, for example. The fixing unit 130 receives the media (normally paper) with the toner applied to it and fixes it to the media. The speed at which the media passes through the printing unit 129 is different from the speed at which the media passes through the fixing unit 130. The speed at which the media passes through the fixing unit 130 is controlled by the firmware of the machine and is a function of the necessary fixing time. The necessary fixing time will differ according to the characteristics of the media, the size of the media and the thickness of the media.

The speed of the media through the fixing unit 130 is controlled by rollers driven by motors within the printer unit. The control system for this process must take into account, amongst other things, the type of media, the length of media and the thickness of the media.

Between the main printer body 128 and the finisher unit 132, a buffer unit 131 is used to, amongst other things, regulate the speed of paper being passed from the main printer body 128 to the finisher unit 132. Other potential uses of the buffer unit 131 are to correct media curvature and/or re-orientate media for the finishing unit.

According to an aspect of the present invention, a spectrophotometer is located within the buffer unit 131 of l0 the printer. One advantage of placing the spectrophotometer within the buffer unit is the space that is typically available within this unit; this reduces the need for expensive miniaturization. In printers without a buffer unit, the spectrophotometer could be located within the printer, as long as it is close enough to the paper path and after the fixing unit 130. By way of example, spectrophotometers (or at least the optical heads) proposed by GretagMacBeth or X-Rite could be used with the present invention.

When a patch page is printed by the printer main body 128, the spectrophotometer in the buffer unit 131 is used to measure the colour performance of the printer and a file representing the measured patch page is stored in printer memory. The spectrophotometer is located after the fixing unit 130 so that the final, fixed output can be measured.

If necessary, the fixing unit speed can be adjusted to reduce the exit speed of the paper from the fixing unit so that it is at an appropriate speed for the spectrophotometer to read it.

There are a number of possible configurations of the spectrophotometer. Figure 7 shows a first arrangement in which a series of spectrophotometers 134a, 134b...134n, each having a relatively narrow reading head, are spread across - 16 the width of the buffer unit 131 (i. e. across the direction of paper advancement). Figure 8 shows a second arrangement in which a single spectrophotometer 136 with a relatively wide reading head spans the width of the buffer unit. In the arrangement of Figure 8, the single spectrophotometer measures colours across the width of a page moving through the buffer unit.

Standard colour charts, such as the IT8.7/3 chart shown in Figure 5, may be used as the basis for the generation of the destination profile of the printer. The exact nature of the colour chart depends on the spectrophotometer configuration used. For example, if six spectrophotometer heads spread across the width of the advancing page are used, then the colour chart must be arranged such that six strips of colours aligned with the six spectrophotometer heads are printed. If a single, relatively wide spectrophotometer is used, then the colour chart can be spread across the width of the printed page.

Methods of measuring toner density are already known but they are not able to guarantee stability of the machine's output. The use of a spectrophotometer in this invention allows the printer to be characterized accurately. This, in turn, allows data to be transformed for optimum colour reproduction.

The destination process generation process can be initiated in a number of ways as outlined below: 1. The user may initiate the process at any time.

2. The system software, stored in a printer's memory, may initiate the process periodically. Thus, if the system software detects that the destination profile has not been updated for a predetermined period, the destination profile building process is initiated. This may, for example, occur every 24 hours, or once per week. In a related manner, the system may be programmed to simply update the destination profile at a set time, such as midnight every day. The destination profile of devices which have an unstable colour performance may need to be updated several times a day (such as every four hours).

Furthermore, even for more stable devices, there is a quality assurance benefit in updating the destination profile regularly.

3.The destination profile may be updated each time the printer is turned on.

4. When the printer receives a job to print, the printer may decide to automatically launch an update of its profile, perhaps as a result of the size of the job (e.g. the number of pages to print) or due to the printing finishing options (e.g. colour, high resolution).

5.The system software may be programmed to detect when the MFP has received maintenance that may effect the printer performance, such as the toner cartridge being replaced.

On detecting such an event, the destination profile generation process is initiated.

6.The system software may be programmed to detect when the printing conditions have changed significantly to affect the quality of the printing. The printing conditions can be defined by: a. Temperature (a sensor being located within the printer) b. Humidity (monitored through a sensor embedded within the printer) c. Toner Density d. Potential control system (to control the quality/quantity of the toner) 7. A destination profile may be generated after a set number of pages have been printed. This may include printing 18 test pages during a large printing batch to ensure that there is no colour variation during that batch.

8.A different destination profile may be required for each media used. Thus, each time a new paper size or a different type of paper is used, a new profile may be generated for that paper.

Of course, combinations of the above-mentioned destination profile generation criteria may be used. Figure 9 is a flow chart showing an exemplary destination profile

generation process. The destination profile generation process is initiated either by the user (step 138) or by the system software (step 140), as discussed above.

Regardless of how the process is initiated, the next step of the destination profile generation process is to print the test chart, such as that shown in Figure 5, at step 142. As discussed above, the test chart will be adapted in accordance with the arrangement of the spectrophotometer(s) used. Those spectrophotometer(s) are then used to measure the colour properties of the printed test chart at step 144. In addition, the speed of the media in the fixing unit 130 may be altered according to the requirements of the spectrophotometers.

The printer comprises an internal memory, in which a file representing the test chart is stored. The printer also comprises a RAM, ROM and memory to store the programmes and files necessary for launch of the profile update. The programme, test chart and file can be downloaded from a server, website, etc. The memory in which the chart file is stored can be accessed (i.e. deleted, updated, etc.) through the network (via a terminal connected to the - 19 network) or through a laptop computer directly connected to the printer via the interface available (RJ-45 Ethernet port, USE port, Parallel port, etc.) The measured properties of the printed test chart are assessed at step 146 to determine whether or not the destination profile of the printer needs to be updated.

Essentially, this step determines whether the destination profile that is currently stored for the device is sufficiently accurate. If the stored destination profile is accurate, then there is no need to determine a new profile and the process proceeds to step 152 where the normal printer function of the printer is resumed. If the stored destination profile is inaccurate, then a new profile is created at step 148 and that profile is stored as the destination profile of the device at step 152.

The step 146 in which it is determined whether or not the destination profile of the printer needs to be updated can be implemented in a number of ways. In one embodiment of the invention, the colour drift is determined by measuring CIELAB values. This can be done by measuring the delta E difference between the lightness, chrome and hue of the reference file and that of the printed test chart. (There are many definitions of for the delta E value, such as CIEDE2000, CMC and CIE94, that are well known to the person skilled in the art.) If the delta E measurement indicates that a new profile should be created, this is done at step 148 using the method described above. The ICC profile for the printer is then embedded in the device software at step 150 to replace the previous profile. - 20

The decision step 146 may be omitted. In such cases, a new destination profile would be created each time the destination profile generation process is initiated. A reason for not omitting the step 146 is creating a new S destination profile each time the destination profile generation process is initiated may slow down the printing process to an unacceptable degree.

Once a destination profile for the printer is generated, l0 this is stored in the printer memory. In an alternative embodiment, the destination profile may be stored in the network controller 124 of Figure 6. Users may be given access to the destination profile. This may be useful, for example, if the user wishes to simulate the functionality of the printer. This might be desirable if a user particularly liked the colour performance of a particular printer and wanted to re-create that colour performance on a different printer.

Alternatively, the destination profile for the printer can be stored in a central memory accessible to devices (such as terminals and printers) on the network. The destination profile generation programme may also be located remotely from the printer. For example, the destination profile generation programme for a number of MFPs may be stored on a server to which each of those MFPs is connectable.

Claims

Claims: 1. A method of generating a colour performance profile that

describes the colour performance of a printer, the method comprising the steps of: printing a colour test image using said printer; measuring the colour profile of the printed image using a spectrophotometeri and generating said colour performance profile from the outputs of said spectrophotometer, wherein said spectrophotometer is located within the printer and, in use, print media is arranged to pass the spectrophotometer sufficiently slowly so that the spectrophotometer has time to measure the said colour profile.
2. A method as claimed in claim 1, wherein said spectrophotometer is part of a buffer unit of said printer.
3. A method as claimed in claim 2, wherein the buffer unit is located between a main printer body and a finishing unit of the printer.
4. A method as claimed in claim 3, wherein the main printer body comprises a printing unit and a fixing unit, wherein the buffer is located downstream of said fixing unit.
5. A method as claimed in any one of claims 1 to 3, wherein the printer comprises a main printer body comprising a printing unit and a fixing unit, wherein the spectrophotometer is located downstream of the fixing unit.
6. A method as claimed in claim 4 or claim 5, wherein the speed at which the print media exits the fixing unit is - 22 controlled so that it is at an appropriate speed for the spectrophotometer to measure the said colour profile.
7. A method as claimed in any one or claims 1 to 6, wherein said spectrophotometer has a single head that substantially spans the width of a printed image.
8. A method as claimed in any one of claims 1 to 6, wherein a plurality of spectrophotometers are used, said plurality of spectrophotometers substantially spanning the width of a printed image.
9. A method as claimed in any preceding claim, wherein said colour performance profile is compared with the profile of a reference file, wherein said colour performance profile becomes the reference file if the colour performance profile differs from the reference file by more than a predetermined amount.
10. A method as claimed in claim 9, wherein the colour performance profile and the reference profile are compared by determining the delta E difference between those profiles.
11. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated in response to a request from a user.
12. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated in response to detection of an event that is relevant to said profile.
13. A method as claimed in claim 12, wherein said event is maintenance of the printer. - 23
14. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated each time the printer is turned on.
15. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated when a predetermined period has elapsed since the colour performance profile generation was last initiated.
16. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated periodically, according to a programmed schedule.
17. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated when a predetermined number of pages have been printed since the colour performance profile generation was last initiated.
18. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated whenever a new printing media is used.
19. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated whenever a print job exceeds a predetermined size.
20. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated whenever the printing finishing options exceed a predetermined quality setting.
21. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated - 24 on detection of a significant change in the printing conditions.
22. A method as claimed in any preceding claim, wherein said profile is an ICC profile.
23. A method as claimed in any preceding claim, wherein the colour test image is an ANSI IT8.7/2 test chart.
24. A method as claimed in any preceding claim, wherein said colour test image is electronically stored within a memory of said printer.
25. A method as claimed in any preceding claim, wherein said colour performance profile is electronically stored within a memory of said printer.
26. A method as claimed in any preceding claim, wherein the user is given access to said colour performance profile.
27. A printer comprising a spectrophotometer for measuring the colour profile of a colour test image printed by said printer and means for generating a colour performance profile of said printer from said profile measurement, wherein print media is arranged to pass the spectrophotometer sufficiently slowly so that the spectrophotometer has time to measure the said colour profile.
28. A printer as claimed in claim 27, wherein said spectrophotometer is part of a buffer unit of said printer. -
29. A printer as claimed in claim 28, wherein the buffer unit is located between a main printer body and a finishing unit of the printer.
30. A printer as claimed in claim 29, wherein the main printer body comprises a printing unit and a fixing unit, wherein the buffer is located downstream of said fixing unit.
31. A printer as claimed in any one of claims 27 to 29, wherein the printer further comprises a main printer body comprising a printing unit and a fixing unit, wherein the spectrophotometer is located downstream of the fixing unit.
32. A printer as claimed in claim 30 or claim 31, wherein the speed at which the print media exits the fixing unit is controlled so that it is at an appropriate speed for the spectrophotometer to measure the said colour profile.
33. A printer as claimed in any one of claims 27 to 32, wherein said spectrophotometer has a single head that substantially spans the width of the printed image.
34. A printer as claimed in any one of claims 27 to 32, wherein a plurality of spectrophotometers are used, said plurality of spectrophotometers substantially spanning the width of the printed image.
35. A printer as claimed in any one of claims 27 to 34, wherein said printer further comprises a network controller for receiving print instructions from one or more sources on a network and converting said instructions into raster image data for printing on said printer.
36. A printer as claimed in any one of claims 27 to 35, wherein said colour performance profile is compared with the profile of a reference file, wherein said colour performance profile becomes the reference file if the colour performance profile differs from the reference file by more than a predetermined amount.
37. A printer as claimed in claim 36, wherein the colour performance profile and the reference profile are compared by determining the delta E difference between those profiles.
38. A printer as claimed in any one of claims 27 to 37, further comprising means for initiating the colour performance profile generation in response to a request from a user.
39. A printer as claimed in any one of claims 27 to 38, further comprising means for initiating the colour performance profile generation in response to an event that is relevant to said profile.
40. A printer as claimed in claim 39, wherein said event is maintenance of the printer.
41. A printer as claimed in any one of claims 27 to 40, further comprising means for initiating the colour performance profile generation each time said printer is turned on.
42. A printer as claimed in any one of claims 27 to 41, further comprising means for initiating the colour performance profile generation when a predetermined period has elapsed since the colour performance profile generation was last initiated. - 27
43. A printer as claimed in any one of claims 27 to 42, further comprising means for initiating the colour performance profile generation periodically, according to a programmed schedule.
44. A printer as claimed in any one of claims 27 to 43, further comprising means for initiating the colour performance profile generation when a predetermined number of pages have been printed since the colour performance profile generation was last initiated.
45. A printer as claimed in any one of claims 27 to 44, further comprising means for initiating the colour performance profile generation whenever a new printing media is used.
46. A printer as claimed in any one of claims 27 to 45, further comprising means for initiating the colour performance profile generation whenever a print job exceeds a predetermined size.
47. A printer as claimed in any one of claims 27 to 46, further comprising means for initiating the colour performance profile generation whenever the printing finishing options exceed a predetermined quality setting.
48. A printer as claimed in any one of claims 27 to 47, further comprising means for initiating the colour performance profile generation on detection of a significant change in the printing conditions.
49. A printer as claimed in any one of claims 27 to 48, wherein said profile is an ICC profile. - 28
50. A printer as claimed in any one of claims 27 to 49, wherein said colour test image is an ANSI IT8.7/2 test chart.
51. A printer as claimed in any one of claims 27 to 50, wherein said colour test image is electronically stored within a memory of said printer.
52. A printer as claimed in any one of claims 27 to 51, JO wherein said colour performance profile is electronically stored within a memory of said printer.
53. A printer as claimed in any one of claims 27 to 52, wherein the user is given access to said colour performance profile.
54. A device comprising a printer as claimed in any one of claims 27 to 53 and further comprising a scanner.
55. A device as claimed in claim 54, wherein said device further comprises a photocopying function.
56. A computer program product arranged, when executed, to generate a colour performance profile of a printer, wherein the colour performance profile is determined by printing a colour test image, measuring the colour performance profile of the printed colour test image using a spectrophotometer, and generating the colour performance profile from the outputs of the spectrophotometer, wherein said spectrophotometer is located within the printer and print media is arranged to pass the spectrophotometer sufficiently slowly so that the spectrophotometer has time to measure the said colour profile. - 29
57. A product as claimed in claim 56, wherein the colour performance profile is compared with the profile of a reference file, wherein said colour performance profile becomes the reference file if the colour performance S profile differs from the reference file by more than a predetermined amount.
58. A product as claimed in claim 57, wherein the measured colour performance profile and the reference colour performance profile are compared by determining the delta E difference between those profiles.
59. A product as claimed in any one of claims 56 to 58, wherein the colour performance profile generation is initiated in response to a request from a user.
60. A product as claimed in any one of claims 56 to 59, wherein the colour performance profile generation is initiated in response to detection of an event that is relevant to said profile.
61. A product as claimed in claim 60, wherein said event is maintenance of the printer.
62. A product as claimed in any one of claims 56 to 61, wherein the colour performance profile generation is initiated when the printer is turned on.
63. A product as claimed in any one of claims 56 to 62, wherein the colour performance profile generation is initiated when a predetermined period has elapsed since the colour performance profile generation was last initiated. - 30
64. A product as claimed in any one of claims 56 to 60, wherein the colour performance profile generation is initiated periodically, according to a programmed schedule.
65. A product as claimed in any one of claims 56 to 64, wherein the colour performance profile generation is initiated when a predetermined number of pages have been printed since the colour performance profile generation was last initiated.
66. A product as claimed in any one of claims 56 to 65, wherein the colour performance profile generation is initiated whenever a new printing media is used.
67. A product as claimed in any one of claims 56 to 66, wherein the colour performance profile generation is initiated whenever a print job exceeds a predetermined S1 ze.
68. A product as claimed in any one of claims 56 to 67, wherein the colour performance profile generation is initiated whenever the printing finishing options exceed a predetermined quality setting.
69. A product as claimed in any one of claims 56 to 68, wherein the colour performance profile generation is initiated on detection of a significant change in the printing conditions.
70. A product as claimed in any one of claims 56 to 69, wherein said profile is an ICC profile.
71. A product as claimed in any one of claims 56 to 70, wherein the colour test image is an ANSI IT8.7/2 test chart. - 31
72. A product as claimed in any one of claims 56 to 71, wherein said colour test image is electronically stored within a memory of said printer.
73. A product as claimed in any one of claims 56 to 72, wherein said colour performance profile is electronically stored within a memory of said printer.