EP1492079A1 - Method of output of a digital document from an application not provided for colour management on an output device, with colour correction by means of an additional program module - Google Patents

Abstract

Method for output of a digital document to an output unit controlled by an output computer. According to the method monitor (MP) and output (BP) unit profiles are stored in the output computer and used with a color-management free application (A) that interacts with a program module (PM) installed in a color transformation unit (CMM) that provides color management functionality for converting an electronic document (D) prior to its printing on the output unit (B).

Description

The invention relates to a method for outputting a digital document on an output device controlled by an output computer according to the preamble of the independent claim.

In digital color reproduction processes, color management methods and color management systems are generally used to improve color fidelity. A comprehensive and clear presentation of the background, technologies and applications of color management systems can be found in the publication "Postscript on Color Management, Philosophy and Technology of Color Management." Published by the company Logo GmbH, a company of the Gretag-Macbeth Group, in August 1999 "the authors Stefan Brües, Liane May and Dietmar Fuchs. Another paper on color management can be found, for example, in Chapter 17 "Device-Independent Color Imaging" of the book "Color Appearance Models" by Mark D. Fairchild, first edition, published in 1997 by Addison Wesley. Further explanations can also be found in the relevant publications of the International Color Consortium (ICC).

A color management system allows a color-true reproduction of an image template in a digital workflow, which can include an input medium (eg scanner or digital camera and several output media (eg monitor, digital projector and printer) The RGB image can be displayed on the monitor or by means of a beamer, or converted into printing inks for output on a printer.The color-true reproduction is achieved through the use of device profiles and color space transformations reached on the basis of these device profiles.

A device profile describes the color space of an input or output device by giving the device-specific color values (eg RGB or CMYK) absolute color values (XYZ or CIELab L * a * b *) according to the specifications of the CIE (Commission Internationale de l'Eclairage ) or other non-device-specific color values (eg sRGB) assigns. A device profile typically consists of various color value replacement tables (look-up tables) and coefficients of a color space transformation matrix.

For color-true image reproduction, the Color Management System combines the profile of the input medium (source profile) and the profile of the output medium (target profile) to obtain a transfer characteristic. The color management system also performs a mapping of the color space of the input device to the color space of the output device. This illustration ensures that all colors can be displayed on the output medium. The picture, d. H. The rescaling of the color spaces is carried out according to various reproduction criteria, the so-called rendering intents. A distinction is made between the modes "Perceptual" (same color impression in the picture), "Relative Colorimetric", "Absolute Colorimetric" and "Saturation", which are defined in the document ICC-1: 1998-09 of the International Color Consortium (ICC).

In place of the input medium can also be an application program, with which the image template on the screen can be created directly in digital form. In order for the methods of color management to be applicable in this case too, this application program (referred to below as the application for short) must contain a color management system and access and process profiles. Ideally, such an application is fully ICC compliant, so that it can access and use the basic color management functions provided by the computer's operating system. However, in practice, currently widespread presentation applications such as e.g. Microsoft PowerPoint or Apple Keynote are not ICC compliant, or at least they do not have a color management system or can not access and process profiles. Such applications are referred to below as colorless management applications. Therefore, documents created with such applications (presentations) usually result in the presentation with a digital projector (beamer) or the expression of a color impression on the monitor on which they were created, often significantly different color impression.

The present invention is now to overcome this difficulty and create a possibility in the output of created by means of color management applications digital documents on an output device, especially a digital projector, the most accurate color match between reach the monitor display and the display generated by the output device.

The solution of this problem underlying the invention results from the features described in the characterizing part of the independent claim features of the invention. Further developments and advantageous embodiments are the subject of the dependent claims.

Fig. 1

das Prinzip der Erstellung eines digitalen Dokuments mit einem Anwendungsprogramm auf einem Rechner,

Fig. 2

ein Blockschema der erfindungsgemässen Ausgabe eines digitalen Dokuments auf ein Ausgabegerät und

Fig. 3

eine Blockschema der relevanten Schritte des erfindungsgemässen Verfahrens.

In the following the invention will be explained in more detail with reference to the drawing. Show it:

Fig. 1

the principle of creating a digital document with an application program on a computer,

Fig. 2

a block diagram of the inventive output of a digital document to an output device and

Fig. 3

a block diagram of the relevant steps of the inventive method.

The creation of a digital document D, for example a presentation, to be presented later (to be output at an output device) takes place on a preparation computer RE by means of a color management-less application A running thereupon, for example Microsoft Power Point. On the preparation computer RE, a monitor M is connected, on which the document D is displayed visually during the creation. When creating the digital document D no color management is involved. The finished digital document D is then in the form of a digital file.

The later presentation of the digital document D is normally carried out on another computer via a suitable output device, typically a digital electronic projector (projector) B, which is connected to this other computer designated here as output computer RA and is controlled by it (FIG. , The same color management application A is installed on the output computer RA. The digital document D is loaded in the usual way in the application A (opened with the application A) and can be output to the projector B in the usual way. Optionally, the digital document D can also be displayed on a monitor, not shown here, belonging to the output computer RA.

As far as the invention fully complies with the known prior art, for which the expert requires no further explanation.

As already mentioned, the color impression of the visual display of the digital document D produced by the digital projector B (or other output device) as a rule differs considerably from that of the monitor display when the digital document is created. In order to achieve optimum color matching even in a color management-less application A, a special program module PM is installed on the output computer RA according to an essential main aspect of the invention, which provides the functionalities of a color management system for the current application A. (Figure 2).

This program module PM contains, on the one hand, a color transformation unit CMM and, on the other hand, interface functions F, which allow it to access the digital document D loaded in the application A and to change this within the application A. In the interface functions F further unspecified routines are also included, by means of which, possibly taking into account the possibly provided by the operating system of the output computer RA basis color management functions on the output computer RA stored ICC profile files MP, PCS, BP can be accessed ,

The color transformation unit CMM is nothing more than a fast computing software e.g. in the form of a stand-alone dynamic program library (DLL) containing the necessary mathematical algorithms for color conversion. ICC profiles provide the corresponding parameters and fill the mathematical algorithms with values. The color transformation unit CMM used may be a commercially available color management module, preferably the Color Management Module "LogoSync" developed by the aforementioned company Logo GmbH.

The program module PM is typically designed as a supplementary module (add-in) to application A, wherein the interface functions F form the software-technical framework for the supplementary functions in the existing application A. The programming of this framework is based on the specifications of application A for the creation and integration of supplementary modules (add-ins).

Further details of the practical implementation of the program module PM will be explained below.

The inventive method now proceeds as follows:

First, an ICC device profile referred to below as the monitor profile MP is generated by the monitor M on which the digital document D was created. This can be carried out in a manner known per se by means of commercially available measuring devices and associated profiling programs. Particularly suitable is the profiling software "EyeOne Match", marketed by the aforementioned company Logo GmbH, in conjunction with the spectrophotometer EyeOne marketed by Gretag-Macbeth AG, also mentioned above. How this is done in detail is described in the documentation of this profiling software as well as e.g. also described in detail in EP-A-1 150 159. The monitor profile MP is then stored in the output computer RA as a file with a standardized format.

Next, an output device profile BP is generated in an analogous manner from the output device used for the purpose, here for example by the digital projector B, and likewise stored in the output computer RA. The generation of a device profile for a digital projector is also described in detail in EP-A-1 150 159.

Now the application A installed on the output computer RA is started and the digital document D is loaded into the application A or opened with the application A.

Instead of outputting the document D directly from the application A to the output device B, a color transformation is now first carried out by means of the program module PM, whereby the digital document D (or the data representing it) is transformed into a transformed one according to the methods of color management digital document D 'is converted. This color-transformed digital document D 'is then output from the application A to the output device, here the digital projector B.

The color transformation is, as already mentioned, carried out by means of the program module PM. The interface functions F access the data of the digital document D in application A and feed them to the color transformation unit CMM. In addition, the interface functions F load the monitor profile MP stored on the output computer RA, the output device profile BP stored there as well as the working color space profile PCS (normally sRGB) stored or provided by the operating system into the color transformation unit CMM. The actual color transformation (conversion into the color space of the output device B) is performed by the color transformation unit CMM, which uses the monitor profile MP as the source profile and the output device profile BP as the target profile. The conversion itself takes place in a manner known per se and, if necessary, taking into account the so-called rendering intent mentioned in the introduction (typically "perceptual" by default). The data of the converted or color-transformed digital document D 'are fed back to the application A via the interface functions F and replace there the data of the original digital document D. Subsequently, the interface functions F causes the output of the converted document D' to the output device B. , The conversion preferably takes place separately for all objects contained in the digital document D.

In Fig. 3, the above method steps are summarized again clearly.

It is understood that for each combination of a specific monitor M and a specific output device, e.g. Projector B two specific device profiles MP and BP must be created. Since the characteristics of the projection surface and the ambient light conditions are included in the color reproduction process, especially in the case of a digital projector, it is advantageous to generate a plurality of output device profiles BP for different constellations and store them on the output computer RA, in which case only the respectively appropriate output device profile BP is used comes. Of course, if monitor M and output device B do not change, the associated device profiles MP and BP need only be generated once and can then be used for color accurate output of various digital documents D.

The program module PM preferably provides the application A with an additional menu function, by means of which the user can make various selections and make adjustments as well as start the color transformation and subsequent output of the color-transformed digital document. For example, you can In this way, different working color spaces, different monitor profiles MP and different output device profiles BP can be selected, whereby of course it is a prerequisite that these color space and device profiles are present on the output computer RA. Another menu item could be the selection of a rendering intent that will be used if the source color space (of the monitor M) is larger than the target color space (of the output device B), ie a color space adjustment (gamut mapping) is required is. Furthermore, a menu item can also be provided, which activates the recognition of ICC profiles embedded in image objects of the digital document D, so that these embedded profiles can be used in the color transformation.

In the case of Microsoft PowerPoint as application software A, the implementation of the program module PM as a supplementary module (add-in) is comparatively simple. Like all recent versions of Microsoft Office applications, PowerPoint includes the Visual Basic for Applications (VBA) programming language. With this programming language created routines (VBA scripts) can be saved as a module and manually or automatically loaded as an add-in to the application and run from there. VBA makes all objects, properties and methods of PowerPoint available and allows their almost arbitrary manipulation. VBA makes it easy to integrate additional menus into PowerPoint, from which additional functions implemented as VBA code can be triggered. In particular, VBA provides the object "Presentation" that represents the loaded digital document with its contained objects and allows access to it. With VBA, e.g. the image data of the digital object are copied into a buffer and are transferred from there to the color transformation unit CMM for conversion. After that, another VBA routine reads out the converted data from the color transformation unit CMM and writes it back into the object "presentation" in a suitable form (whereby the original data is replaced, ie a modified presentation is created.

In other applications, the procedure is analogous, but if necessary, another programming language is used. The basic functions and processes are the same.

It is understood that the presentation or general output of the digital document D on the output device can also be made from the same computer on which the digital document was created. In this case, of course, the program module PM and the device profiles would have to be installed on the build computer RE. The above statements therefore apply mutatis mutandis to this case.

Furthermore, it is of course also possible to store the digital document D on a e.g. to display the output monitor connected to the output computer RA. In this case, this monitor would constitute the output device, and instead of the beamer profile BP, an output monitor profile generated for this output monitor would have to be used as the output device profile. The same applies if, as output device, e.g. a printer is used.

Claims (6)

A method of outputting a digital document on an output computer controlled output device, wherein the document (D) to be output has been created with a color managementless application (A) installed on a monitor (RE) with monitor connected (M), and wherein the colorless management application (A) is installed on the output computer (RA) and is used via the latter to output the document (D) to the output device (B), characterized in that an ICC-compliant monitor profile (MP) for the monitor (M ) of the creation computer (RE) and stored on the output computer (RA) that an ICC-compliant output device profile (BP) for the used to be used output device (B) is generated and stored on the output computer (RA) that on the output computer (RA) a program module (PM) containing a color transformation unit (CMM) is installed, which cooperates with the colorless management application (A) and that it provides a color management functionality, wherein the program module (PM) can access the electronic document (D) to be output in the application (A), Module (PM) provided color management functionality using the stored monitor profile (MP) and the stored output device profile (BP) the electronic document (D) by the color transformation unit (CMM) in the color space of the output device (B) converted and that the thus converted document (D ') is output from the application (A) to the output device (B). A method according to claim 1, characterized in that a digital electronic projector (B) is used as the output device. A method according to claim 1 or 2, characterized in that the colorless management application (A) is one for the preparation of presentations. Method according to one of the preceding claims, characterized in that the program module (PM) as a supplementary module for color management Application (A) is formed. Method according to one of the preceding claims, characterized in that the transformation of the document (D) into the color space of the output device (B) takes place according to the principles of color management defined by the ICC. Method according to one of the preceding claims, characterized in that for the transformation of the document (D) by means of the color transformation unit (CMM), the monitor profile (MP) is used as the source profile and the output device profile (BP) as the destination profile.

Images