GB2407932A

GB2407932A - Method of generating colour performance profile for scanner

Info

Publication number: GB2407932A
Application number: GB0325862A
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: 2005-05-11
Anticipated expiration: 2023-11-05
Also published as: GB2407932B; GB0325862D0

Abstract

A colour performance profile, such as an International Color Consortium (ICC) profile describing the colour response of a scanner, is generated by scanning a test image 92, mounted on a scanner lid background surface. The colour test image may be movable such that, during normal document scanning, it does not face the scanning surface 88; test image 92 may be part of a feeder belt 90, rotating to retract the colour test image to a hidden, standby state. Positioning of the colour test chart 92 may be measured by the position of a monochromatic reference band. The colour performance profile may be attached to a scanned image either automatically or by user selection. Generation of the colour performance profile can be initiated each time the scanner is switched on, after a certain scan number, by an event such as periodic, routine maintenance or after a predetermined time period.

Description

Automatic Generation and Use of Colour Profiles for Scanners The present

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

Traditional office photocopiers, scanners and printers have 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 l6. The scanned image is then 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 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 workilow 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 Colorsync within their operating system. MicrosoftTN 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.

1S 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 - 7 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

The inventor has noticed that the method described above for generating a source profile for a scanner suffers from a number of problems including: The test chart may be lost or mislaid.

The test chart must be manually positioned on the scanner.

The border of the test chart must be identified in the scanned image.

The test chart may be skewed when positioned on the scanner.

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

A profile must be manually built for each scanner that is used and this profile may require regularly updating.

The scanner-specific profile must be attached to each image that is scanned using the scanner.

The user must have access to all of the hardware and software required to generate the source profile. In addition, he/she must manually select the correct profiles for the relevant scanner. The more complex the environment, the more complicated (and prone to error) the selection of the correct profile becomes.

The user needs to be well acquainted with all of the appropriate software, especially the profile generation software. Operator errors, either through not being sufficiently proficient at using the software or not understanding the importance of the process, are often the most significant source of errors.

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 9 - of measurements of the printed colours using a spectrophotometer to measure the spectral response of reflected light to build an ICC compliant profile.

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 scanner, the scanner having a scanning surface and a scanning background surface, said scanning background surface having a colour test image mounted thereon, wherein, in a colour performance profile generation mode of said scanner, the scanning background surface is positioned such that the colour test image is located at a scanning position facing the scanning surface, the method comprising the step of scanning the colour test image to produce said colour performance profile.

The present invention also provides a scanner comprising a scanning surface and a scanning background surface, said scanning background surface having a colour test image mounted thereon, wherein, in a colour performance profile generation mode of operation of said scanner, the scanning background surface is positioned such that said colour test image is located at a scanning position facing the scanning surface.

The method and scanner of the present invention address many of the problems identified above. Mounting the colour test image on the scanning background surface means that that colour test image does not need to be manually positioned on the scanning, will not be mislaid, and will not require careful storing. The method is largely - 10 automatic, thereby addressing many of the operator-related problems noted above.

In a normal scanning mode of the scanner, the colour test image may be positioned in said scanning position.

Alternatively, in a normal scanning mode of the scanner, the colour test image may be positioned in a stand-by position that does not face the scanning surface.

Moving the colour test image to a stand-by position is more complicated but does have the advantage of ensuring that no part of the colour test image will be scanned during a normal operating mode of the scanner.

In one embodiment of the invention, an initialization routine is provided for positioning the colour chart on the scanning background surface. This is advantageous since if the colour chart is precisely positioned, then the generation of the colour performance profile is straightforward.

The initialization routine may include comparing intended and measured positions of the colour chart. In one form of the invention, the intended and measured positioned of the colour chart are defined in terms of distances between edges of the colour test chart and corresponding edges of a sheet of paper relative to which the colour chart is positioned. In another form of the invention, the measured position of the colour chart is determined by detecting the position of a monochromic band that is located at a known position on the colour chart. The initialization routine preferably includes the step of adjusting said scanning position so that it is equal to said intended scanning position.

In one embodiment of the invention, an image of the colour test image is extracted from the scanned colour test image to generate said colour performance profile. This may, for example, be achieved using an edge detection algorithm.

This reduces the need to know the exact position of the colour chart, and hence reduces the need for the initialization routine.

The colour performance profile may be automatically attached to an image scanned in a normal scanning mode.

Alternatively, the user may be given the option of whether or not said colour performance profile is attached to an image scanned in a normal scanning mode.

There are a number of other options that may be given to the user, such as selecting the destination of a scanned file is selected by the user. In some circumstances, a user may be given a reduced set of options. Furthermore, there a set of default options may be provided in the event that the user does not indicate a preference for one or more of the options available.

The colour performance profile generation may be initiated in one of many ways. For example, in response to a request from a user or under the instruction of the system software that controls the scanner.

In some embodiments of the invention, the colour performance profile generation may be initiated by one or more of the following circumstances: in response to detection of an event that is relevant to said profile (such as maintenance of the scanner); when a predetermined period has elapsed since the colour performance profile generation was last initiated; periodically, according to a programmed schedule (e.g. once per day); each time the - 12 scanner is turned on; and when a predetermined number of images have been scanned since the colour performance profile generation was last initiated. Any combination of the options listed above may apply in any particular embodiment of the invention.

An image scanned by said scanner may be transformed into a standard colour space. The colour performance profile may be an ICC profile. The colour test image is an ANSI ITS.7/2 test chart; other suitable test charts are known to the skilled person.

In one form of the invention, the scanning background surface of said scanner forms part of a feeder belt. The scanner may include a document feeder and, in a normal scanning mode of the scanner, said feeder belt may be arranged to rotate in order to feed paper from said document feeder to said scanning surface. Furthermore, in a normal scanning mode of said scanner, before said rotation of said feeder belt said colour test image may be located in a stand-by position that does not face the scanning surface, and after said rotation of said feeder belt said colour test image may be located in said scanning position. Alternatively, the feeder belt may be prevented from rotating.

In another form of the invention, the scanner is a flat-bed scanner, wherein said scanning background surface is part of a lid of said scanner.

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

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

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 6a shows an MFP in accordance with an embodiment of the present invention) FIGURE 6b shows another view of the MFP of Figure 6ai FIGURE 7 shows a number of internal features of the MFP of Figures 6a and 6bi FIGURE 8 shows the position of a colour chart on a document feeder of an MFP in accordance with an aspect of the present invention) FIGURE 9a shows a first alignment of a colour chart during the use of an MFP in accordance with an embodiment of the present invention) FIGURE 9b shows a second alignment of a colour chart during the use of an MFP in accordance with an embodiment of the present invention) FIGURE 9c shows a third alignment of a colour chart during the use of an MFP in accordance with an embodiment of the present invention) FIGURE 10 is a flow chart showing a source profile generation process in accordance with an aspect of the present invention; FIGURE 11 is a flow chart demonstrating the use of a source profile in accordance with an aspect of the present invention; FIGURE 12 is a flow chart demonstrating the use of a source profile in accordance with another aspect of the present invention; Figures 6a and 6b show an MFP, indicated generally by the reference numeral 86, that is suitable for use with the present invention. MOP 86 includes a scanning surface 88 and an automatic feeder belt 90. The feeder belt 90 provides a background for the scanning process and also includes a colour chart 92, such as the ANSI IT8.7/2 colour chart of Figure 5, mounted thereon. The colour chart 92 is best shown on Figure 6b. The colour chart 92 may be directly printed onto the feeder belt 90. Alternatively, the colour chart 92 may be attached or fixed in some way to the feeder belt 90.

As discussed above, a source profile for a scanner can be generated by scanning a colour chart, such as that of Figure 5, using a scanner and manipulating the data using profile generating software to generate the source profile.

In accordance with an embodiment of the present invention, the source profile is generated by automatically positioning the belt so that the colour chart is precisely positioned in a predetermined position relative to the scanner surface and then scanning the colour chart to generate the profile. If the position of the colour chart is precisely known, it is not necessary to edit the profile using profile generation software. Precise positioning of - 15 the colour chart on the scanner surface is achieved using an initialization routine described in detail below.

In some prior art devices, a source profile is attached to the file of a scanned image by a user working at a computer terminal. The present invention differs from that arrangement in having a programme working within the MFP.

The source profile is attached to the file within the MFP under the control of that programme before the file is output by the MFP. This process is automatic and invisible to the user.

Figure 7 shows a number of internal features of the MFP 86.

An internal network 50 is used to connect together a CPU 200, ROM 201, machinery module 202, memory 203, RAM 205, network controller 206 and user interface 207. The user interface 207 is connected to a graphical user interface 208. The network controller 206 is connected to a network, such as Internet network 101. The machinery module 202 is used to monitor the position of the belt of the MFP and other aspects of the machinery 210 of the MFP. The memory 203 is used for storing colour profiles and programmes for controlling the generation of colour profiles and the attachment of colour profiles to scanned documents.

In an alternative embodiment of the invention, the source profile generation programme could be located remotely from the MFP 86 and in communication with the MFP via network 101. For example, the source profile generation programme for a number of MFPs could be stored on a server to which each of those MFPs is connectable.

In the example of Figures 6a and 6b, the colour chart is located on the feeder belt such that, when the feeder belt - 16 is in the scanning position, the colour chart is in the top left hand corner of the scanner surface.

In one embodiment of the invention, the colour chart remains in the same position relative to the scanner surface throughout the use of the MFP. In this embodiment, any document placed directly onto the scanning surface that is larger than the colour chart will be copied correctly, but any document that is smaller than the colour chart would risk part of the colour chart being copied. This problem can be minimised by ensuring that the colour chart is relatively small.

If an MFP with a document feeder is used, when a document to be scanned is inserted into the feeder, the feeder belt rotates to bring the document above the scanning surface.

As a consequence, the colour chart will not appear on the scanning surface at the time when the document is scanned.

In one embodiment of the invention, the rotation of the feeder belt is blocked when the profile generation programme is launched in order to prevent the colour chart from being moved away from the scanning surface of the MFP.

An alternative means of addressing the problems associated with the colour chart moving with the feeder belt is shown with reference to Figure 8. Figure 8 shows a feeder belt 51 that is rotatable in the direction indicated by arrow 52. In a scanning mode of operation, a sheet of paper 54 is inserted into the MFP by a document feeder (not shown) and moved into a scanning position by the rotation of the feeder belt 51. In this embodiment, the colour profile is not located on the scanning surface when the feeder belt is in a stand-by position. Rather, the position of the colour chart is determined by the fact that when the feeder belt is rotated in the normal photocopying or scanning mode of - 17 the MFP, the colour chart does not face the scanner surface. More specifically, when a document is put in the document feeder, the left edge of the colour chart should appear (relatively) on the right side of an imaginary line L on the feeder belt at the position indicated by the reference numeral 56 in Figure 8. The line L is defined as a vertical line about the translation direction of the belt. The line goes through a point defined as the first contact point between a document's left edge and the feeder belt (the point 58 in Figure 8) when the document is feed from the paper feeder.

In this embodiment of the invention, it is important that the position of the belt is monitored so that the colour chart can be precisely positioned when the profile generation software is launched. In a first embodiment, the belt in monitored so that the colour chart is precisely positioned in known position (preferably the top left corner of the scanner surface) above the scanner surface when the profile generation software is launched. When the scanning of the colour profile starts, the rotation of the feeder belt is blocked and the scanning head is moved back and forth.

In a second embodiment, the feeder belt is rotated normally, as if a document was inserted in the document feeder (the programme needs to check beforehand that no document is located on the document feeder). Again two options are possible, either the scanning head is fixed or it moves back and forth together with the feeder belt. The rotation speed of the feeder belt is controlled depending on the chosen option. Depending on the scanning head, scanning can be more accurate depending on the selected options. - 18

INITIALISATION

Whatever embodiment chosen for the positioning of the chart on the belt, it is necessary to be able to correct any offset in the position of the belt, as well as to correctly position the belt at the manufacturing stage (or when replacing the belt, if necessary). This is achieved by performing the initialization routine described below.

l0 In a preferred embodiment, it is assumed that the colour chart is roughly correctly positioned at an initial stage.

The page format for the scanning is specified to the printer (eithermanually or automatically). By default it can be A4 Portrait. The scanner head scans the feeder belt: Is the same steps as for a normal colour profile update are carried out. The resulting scanned image is used to determine the position of the colour chart in relation to the scanning surface. Position parameters X1, X2 are stored in the printer memory. The parameters X1, X2 define the intended position of the colour chart on a page format A4 Portrait (it could be As, B4, etc. as long as the format is the same as the format used for scanning the colour chart).

X1 defines the intended distance between the left long edge of the A4 page and the left edge of the colour chart. X2 defines the intended distance between the right long edge of the A4 page and the right edge of the colour chart. A programme stored in the printer memory analyses the scanned document and determines the positions of the colour chart relative to the page format. XlScan defines the measured distance between the left long edge of the A4 page and the left edge of the scanned colour chart. X2scan defines the measured distance between the right long edge of the A4 page and the right edge of the scanned colour chart. Such a programme could perform edge detection according to - 19 intensity transition between the colour chart and the

feeder belt background.

Figures 9a, 9b and 9c each show an A4 page 60 with the intended position 62 of a colour chart relative to the A4 page 60 shown in dotted lines. Exemplary measured positions of a colour chart are shown in each of Figures 9a, 9b and 9c. In the example of Figure 9a, the measured position is to the right of the intended position and is labelled 64a. In the examples of Figures 9b and 9c, the measured positions are both to the left of the intended position and are labelled 64b and 64c respectively.

An offset between the intended position of the colour chart and the measured position is defined as follow: If xl 0, Offset = X1 - XlScan; If xl = 0 (indicating that only part of the colour chart has been scanned), Offset = X2scan - X2.

In the example of Figure 9a, xl 0 so the offset is given by X1 - X1scan' which is negative (since Xlscan > X1). In the example of Figure 9b, xl = 0 so the offset is given by X2scan - X2, which is positive. In the example of Figure 9c, xl 0 so the offset is given by X1 - X1scan' which is positive.

The negative offset of Figure 9a indicates that the colour chart is to the right of the intended position and the positive offsets of Figures 9b and 9c indicate that the colour chart is to the left of the intended position. The negative value in Figure 9b is larger than that of Figure 9c indicating that the colour chart is further away from the intended position in Figure 9b than in Figure 9c. -

Alternatively, it is possible to use either parameter (Xlscan,Xl) or (X2sCan,X2) and the width of the scanned colour chart Wscan associated with the width of the original colour chart W to indicate the offset.

The offset value is used to rotate and position the belt to the exact stand-by position, for example under the control of the machinery control module 202 of Figure 7.

l0 In another alternative, the colour chart comprises along its left side (or at a known distance from it) a large monochromic band (preferably a dark colour such as black).

The determination of the offset is based upon the detection of the position of the dark colour edge. The determination of the position of a monochromatic (dark colour) band on a light colour background can be made very accurate when using edge detection according to intensity transition.

In a further embodiment, the feeder belt is scanned until it detects the edge of the colour chart (or of the dark colour band). The detection could be again based upon intensity transition. As soon as the edge is detected, the value of a parameter is read. The parameter may be the rotation angle of the feed belt roller (measured from 0 to MAX, with MAX being the number of increments necessary for the belt to have made one complete rotation and zero representing the standby position of the belt). Once the scanning is completed, the value of the parameter is used to rotate the belt to the exact stand-by position and the value is reset to zero.

The initialization programme as defined above can be stored within the printer itself. It can be also stored remotely on a computer connected to the printer. For example, the programme can be installed on laptop computers used by - 21 maintenance engineers. During maintenance of the printer, an engineer's laptop computer can be connected directly to the printer (for instance via USE port or RJ-45 Ethernet port or Parallel port, etc.) to run the initialization programme from that laptop computer.

It should be noted that although Figures 6a and 6b show an MFP, the present invention is also suitable for use with flat bed scanners (i.e. scanners without a feeder belt).

When using a flat bed scanner, the colour chart can be positioned on the side of the lid of the scanner that faces the scanning surface in the use of the scanner (i.e. the scanning background surface). Preferably, the colour chart faces the top left-hand corner of the scanning surface, as described above.

In the case of flat bed scanners, though the same method could be applied to determine and store as parameters the position of the colour chart relative to the scanning surface, it is also possible to position very accurately the colour chart on the lid when its is manufactured (or at least position marks for stocking the colour chart later on).

SOURCE PROFILE GENERATION

With the colour chart 84 accurately positioned, a source profile can be generated. The source profile building 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 may initiate the process periodically. Thus, if the system software detects that the source profile has not been updated for a - 22 predetermined period, the source 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 source profile at a set time, such as midnight every day. The source profile of devices which have an unstable colour performance may need to be updated several times a day.

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

3. A source profile generation process may be initiated each time the scanner is turned on.

4. The system software may be programmed to detect when the MFP has received maintenance that may effect the scanner performance, such as the scanner lamp being replaced. On detecting such an event, the source profile generation process is initiated.

5. A source profile generation process may be initiated after a set number of pages have been scanned.

Of course, combinations of the above-mentioned profile generation initiation criteria may be used.

Figure lo is a flow chart showing an exemplary source profile generation process.

As shown in Figure lo, the source profile generation process is initiated either by the user (step 94) (for example, through a graphical user interface on a MFP or through a processing device remotely connected to the MFP via a network) or by the system software (step 96), as discussed above. Before the test chart can be scanned, the chart must be in the appropriate position. This may require checking the belt position (step 98) and then moving the belt to the predetermined position (step 100) or 23 blocking the rotation of the belt, depending on the embodiment of the invention. A further step (not shown in Figure 10) of checking the presence of a document in the paper feeder might be required in the case of the feeder belt being rotated, as discussed above. Once the colour chart is in the correct position, it is scanned (step 102) and the profile is generated (step 104). The profile generation is relatively straightforward since, as discussed above, the position of the colour chart is known precisely. The new colour profile is stored in the MFP memory (step 105). The final step is to move the belt to the normal use position (step 106), if necessary.

The programme for the generation of the colour profile can be located in the printer memory (the profile generation options can be set by default when the software is first installed within the printer; they can be modified via the printer panel, or via a laptop computer directly connected to the printer or through a terminal connected to the printer via the network). Alternatively, the software can be stored in another device (such as a server) on the network, the generation of the colour profile would then require the step of sending a request for the generation of a colour profile together with the scanned image and sending the newly generated colour profile back to the printer. Examples of software for the generation of colour profiles include: Gretag-MacBeth, ProfileMaker and Heildelberg PrintOpen Systems.

Clearly, if the colour chart is always left in the same position on the feeder belt 90, then the steps 98, 100 and 106 can be omitted.

In another alternative, it is not necessary to know the exact position of the colour chart (only the approximate - 24 position of the chart need be known), thereby reducing the need for additional control to position the belt at the initialization stage. In such a case, the process comprises an extra step 103 (between steps 102 and 104), wherein the scanned colour chart is extracted from the scanned document using for instance an edge detection programme (according to intensity transition for instance).

Figure 11 demonstrates an exemplary use of the source profile generated, for example, using the process of Figure 10. In Figure 11, an image is scanned at step 108 to produce a scanned file. The source profile is then attached to the scanned file at step 110. Finally, the scanned file, including the attached source profile, is sent to its intended destination at step 112. The destination may, for example, be the file server 4 of Figure 1 or the remote Email client 14 of Figure 1. The attachment of the profile can be arranged to occur automatically so that it is invisible to the user.

By attaching the source profile to the scanned image, the resulting file includes both the scanned image and data concerning the performance of the device used to scan the image. This data can then be used to recreate the original colour of the scanned document.

In a variant of the process of Figure 11, the scanned image may be transformed into the standard colour space before it is sent to its destination, together with the attached source profile. This is possible if the MFP or scanner knows the colour profile of the destination device. It is also possible for an Enterprise to define a "common" colour space. Thus, every image could, for example, be transformed into "Adobe ROB 1998" if that is the "common" space that the Enterprise wishes to store their images in. - 25

An MFP in accordance with the present invention may have a variety of functions. In order to provide the maximum flexibility, the user should be given a range of options when using the device. Figure 12 shows a flow chart demonstrating one method of providing the user with a range of options for using an MFP in a scanning mode.

At step 114, the user selects the scanning parameters. For JO example, a black-and-white option may be available. Also, different resolutions of scan options may be available, and different profiles may be appropriate for different resolutions. Thus, depending on the user's scanning parameters, a profile for 300 dpi colour images, 300 dpi black-and-white images or 600 dpi black-and-white images will be attached to the scanned document. Further, the profile chosen may be dependent on the source material used. For example, colours scanned from matt paper may appear different to colours scanned from glossy paper.

The next step is to select the destination of the scanned image at step 116. Example destinations include local or remote file servers and local or remote Email clients, as discussed in relation to Figure 1.

With the profile and destination chosen, the document to be scanned is scanned at step 118 to produce a scanned image.

The user is then presented with the option of attaching the source profile to the scanned file at step 120. At this stage, the completed scanned document can be sent to its intended destination at step 122.

Clearly, the steps of selecting the profile to be used, selecting the destination of the scanned file, scanning the document and indicating whether or not the source profile - 26 should be attached to the scanned image can be performed in any order. Furthermore, some of the options may not be provided to the user. For example, the user may not be given the option of omitting the step of attaching the source profile to the scanned document. Finally, some of the options may have a default setting in the event that the user does not explicitly state a requirement. The default setting may be to use the source profile generated using the process of Figure 10, to send the scanned document to the local file server and to attach the source profile to the scanned document. - 27

Claims

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

describes the colour performance of a scanner, the scanner having a scanning surface and a scanning background surface, said scanning background surface having a colour test image mounted thereon, wherein, in a colour performance profile generation mode of said scanner, the scanning background surface is positioned such that the colour test image is located at a scanning position facing the scanning surface, the method comprising the step of scanning the colour test image to produce said colour performance profile.
2. A method as claimed in claim 1, wherein, in a normal scanning mode of the scanner, the colour test image is positioned in said scanning position.
3. A method as claimed in claim 1, wherein, in a normal scanning mode of the scanner, the colour test image is positioned in a stand-by position that does not face the scanning surface.
4. A method as claimed in any one of claims 1 to 3, further comprising an initialization routine for positioning the colour chart on the scanning background surface.
5. A method as claimed in claim 4, wherein an intended position of the colour chart is compared with a measured position of the colour chart.
6. A method as claimed in claim 5, wherein the intended and measured positioned of the colour chart are defined in terms of distances between edges of the colour test chart - 28 and corresponding edges of a sheet of paper relative to which the colour chart is positioned.
7. A method as claimed in claim 5, wherein the measured position of the colour chart is determined by detecting the position of a monochromic band that is located at a known position on the colour chart.
8. A method as claimed in any one of claims 5 to 7, wherein said initialization routine further comprises the step of adjusting said scanning position so that it is equal to said intended scanning position.
9. A method as claimed in any preceding claim, wherein an image of the colour test image is extracted from the scanned colour test image to generate said colour performance profile.
10. A method as claimed in any preceding claim, wherein said colour performance profile is automatically attached to an image scanned in a normal scanning mode.
11. A method as claimed in any one of claims 1 to 9, wherein the user selects whether or not said colour performance profile is attached to an image scanned in a normal scanning mode.
12. A method as claimed in any preceding claim, wherein the destination of a scanned file is selected by the user.
13. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated in response to a request from a user. - 29
14. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated by system software that controls the scanner.
15. 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.
16. A method as claimed in claim 15, wherein said event is maintenance of the scanner.
17. 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.
18. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated periodically, according to a programmed schedule.
19. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated each time the scanner is turned on.
20. A method as claimed in any preceding claim, wherein the colour performance profile generation is initiated when a predetermined number of images have been scanned since the colour performance profile generation was last initiated.
21. A method as claimed in any preceding claim, wherein an image scanned by said scanner is transformed into a standard colour space. -
22. A method as claimed in any preceding claim, wherein said colour performance 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 scanning background surface of said scanner forms part of a feeder belt.
25. A method as claimed in claim 24, wherein said scanner includes a document feeder and wherein, in a normal scanning mode of the scanner, said feeder belt is arranged to rotate in order to feed paper from said document feeder to said scanning surface.
26. A method as claimed in claim 25, wherein, in a normal scanning mode of said scanner, before said rotation of said feeder belt said colour test image is in a stand-by position that does not face the scanning surface, and after said rotation of said feeder belt said colour test image is in said scanning position.
27. A method as claimed in claim 25 or claim 26, wherein, in the colour profile generation mode, said feeder belt is prevented from rotating.
28. A method as claimed in any one of claims l to 23, wherein said scanner is a flat-bed scanner, wherein said scanning background surface is part of a lid of said scanner.
29. A method as claimed in any preceding claim, wherein a user is given access to said colour performance profile. - 31
30. A scanner comprising a scanning surface and a scanning background surface, said scanning background surface having a colour test image mounted thereon, wherein, in a colour performance profile generation mode of operation of said scanner, the scanning background surface is positioned such that said colour test image is located at a scanning position facing the scanning surface.
31. A scanner as claimed in claim 30, wherein, in a normal scanning mode of the scanner, the colour test image is positioned in said scanning position.
32. A scanner as claimed in claim 31, wherein, in a normal scanning mode of the scanner, the colour test image is positioned in a stand-by position that does not face the scanning surface.
33. A scanner as claimed in any one of claims 30 to 32, further comprising an initialization means for accurately positioning the colour chart on the scanning background surface.
34. A scanner as claimed in claim 33, wherein the initialization means comprises means for measuring said scanning position and means for comparing said scanning position with an intended scanning position.
35. A scanner as claimed in claim 34, wherein the intended and measured positioned of the colour chart are defined in terms of distances between edges of the colour test chart and corresponding edges of a sheet of paper relative to which the colour chart is positioned.
36. A scanner as claimed in claim 35, wherein the measured position of the colour chart is determined by detecting the - 32 position of a monochromic band that is located at a known position on the colour chart.
37. A scanner as claimed in any one of claims 34 to 36, further comprising means for adjusting said measured scanning position so that it is equal to said intended scanning position.
38. A scanner as claimed in any one of claims 30 to 37, further comprising means for extracting an image of the colour test image from the scanned colour test image in order to generate said colour performance profile.
39. A scanner as claimed in any one of claims 30 to 38, the scanner further comprising means for automatically attaching said colour performance profile to an image scanned in a normal scanning mode.
40. A scanner as claimed in any one of claims 30 to 38, further comprising means to enable the user to select whether or not said colour performance profile is attached to an image scanned in a normal scanning mode.
41. A scanner as claimed in any one of claims 30 to 40, further comprising means to enable the user to select the destination of a scanned file.
42. A scanner as claimed in any one of claims 30 to 41, further comprising means for initiating the colour performance profile generation in response to a request from a user.
43. A scanner as claimed in any one of claims 30 to 42, wherein system software is provided to control the scanner, - 33 wherein the colour performance profile generation is initiated by said system software.
44. A scanner as claimed in any one of claims 30 to 43, further comprising means for initiating the colour performance profile generation in response to an event that is relevant to said profile.
45. A scanner as claimed in claim 44, wherein said event is maintenance of the scanner.
46. A scanner as claimed in any one of claims 30 to 45, 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.
47. A scanner as claimed in any one of claims 30 to 46, further comprising means for initiating the colour performance profile generation periodically, according to a programmed schedule.
48. A scanner as claimed in any one of claims 30 to 47, further comprising means for initiating the colour performance profile generation when a predetermined number of images have been scanned since the colour performance profile generation was last initiated.
49. A scanner as claimed in any one of claims 30 to 48, further comprising means for initiating the colour performance profile generation each time the scanner is turned on.
50. A scanner as claimed in any one of claims 30 to 49, wherein an image scanned by said scanner is transformed into a standard colour space.
51. A scanner as claimed in any one of claims 30 to 50, wherein said colour performance profile is an ICC profile.
52. A scanner as claimed in any one of claims 30 to 51, wherein said colour test image is an ANSI IT8.7/2 test chart.
53. A scanner as claimed in any one of claims 30 to 52, wherein said scanning background surface forms part of a feeder belt.
54. A scanner as claimed in claim 53, further comprising a document feeder, wherein, in a normal scanning mode of the scanner, said feeder belt is arranged to rotate in order to feed paper from said document feeder to said scanning surface.
55. A scanner as claimed in claim 54, wherein, in a normal scanning mode of said scanner, before said rotation of said feeder belt said colour test image is in a stand-by position that does not face the scanning surface, and after said rotation of said feeder belt said colour test image is in said scanning position.
56. A scanner as claimed in claim 54 or claim 55, wherein, in the colour profile generation mode, said feeder belt is prevented from rotating.
57. A scanner as claimed in any one of claims 30 to 52, wherein said scanner is a flat-bed scanner and wherein said scanning background surface is part of a lid of said scanner. -
58. A scanner as claimed in any one of claims 30 to 57, further comprising means to enable a user to access said colour performance profile.
59. A device comprising a scanner as claimed in any one of claims 30 to 58 and further comprising a printer.
60. A device as claimed in claim 59, wherein said device also has a photocopier function.