Photocopying – Projection printing and copying cameras – Detailed holder for photosensitive paper
Reexamination Certificate
1998-02-19
2001-04-03
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Detailed holder for photosensitive paper
C355S075000, C430S022000
Reexamination Certificate
active
06211949
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of aligning at least two images to be scanned and a scanning apparatus for such alignment, where each image has at least one associated alignment area or mark positioned at a given position in relation to the image.
2. Description of Related Art
Alignment of this type is predominantly performed in order to superpose e.g. a number of colour separations, which are typically screened, of an original image or integrating these separations with text in the graphic industry.
In the art, separating the colours of a colour original into e.g. the well-known CMYK or YCMB (Yellow, Cyan, Magenta, Black) colour separations is performed using a computer and suitable software. This separation is performed in order to be able to reproduce the original in e.g. a printing process using the base colours of the colour separation.
In order to be able to precisely position these e.g. four individual and separate representations of the image, the separation also provides alignment or registering marks precisely positioned in relation to the actual image.
Depending on the apparatus producing the colour separations, these alignment or registering marks may be crosses in the film material representing the separations, or the marks may be holes, indentations or notches therein.
In the situation where holes, notches or indentations are provided, these are used in order to precisely position the separations in e.g. the printing machine.
EP 0 200 814 A1 discloses a method for registering colour separation film in order to provide the films with register holes for use in a separate reproduction process.
In the other situation where the marks are crosses or other types of marks or where selected image areas are used for alignment, this positioning in the printing machine may be more difficult.
The same problem may be seen when e.g. desiring to scan the separations to electronically superpose these, as the separations should be positioned very precisely on the scanner.
At present, this positioning of the images is performed by fixing the images on e.g. sheets of transparent film or job-sheets having registering holes for engagement with registering pins on the scanner, in positions where all separations are superposed when positioned on the scanner. Typically, the positioning error should be less than {fraction (5/100)} mm, whereby this work is quite time consuming.
This positioning or aligning of the separations may be carried out based on the alignment marks, but is also possible to select corresponding image areas of each colour separation and use these selected areas as alignment or registering areas.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a solution to this problem of aligning images to be subsequently scanned.
Thus, a first aspect of the invention is to provide a method of aligning and scanning at least two images, each image being associated with at least one corresponding alignment area or mark positioned at a given position in relation to the image, which images when aligned and scanned are arranged on a substantially planar surface of a scanning apparatus for digitizing images. The method according to this aspect of the invention comprises identifying the approximate position of at least one corresponding alignment area or mark associated with each of the images, a first scanning process comprising scanning at least part of the at least one alignment area or mark of the first image directly followed by a complete scanning of the first image, a second scanning process comprising scanning at least part of the at least one alignment area or mark of the second image, determining a displacement(s) of each of the at least one alignment area(s) or mark(s) of the second image in relation to the at least one alignment area(s) or mark(s) of the first image, and cancelling out at least partly the determined displacement(s) of alignment area(s) or mark(s) of the second image directly followed by a complete scanning of said second image.
Here is should be understood that by an alignment area or mark according to the present invention is meant a graphical area or element having a two dimensional structure, which can be unambiguously identified in order to be used for aligning.
In accordance with the present invention it is preferred that the alignment process is an integral part of the image scanning process or processes in which digitized forms of the images are obtained. Thus, it is preferred that the first scanning process comprises scanning the first image in order to obtain a digitized form of the first image, said scanning of the first image preferably being performed after or before scanning of the alignment area(s) or mark(s) of the first image. It is furthermore preferred that the at least partly cancelling out of the determined displacements is followed by a third scanning process comprising scanning the second image in order to obtain a digitized form of the second image.
In order to scan an image or an alignment area or mark, it is preferred that the image or alignment area or mark is moved along a substantially linear path during scanning. The scanning process may be performed by using a scanner head which also or as an alternative can be moved along a substantially linear path during scanning. Preferably, the movement of the image and/or the movement of scanning head defines a direction of scanning.
Typically, a scanning head may comprise one or more CCD-elements, and it is preferred that the direction of scanning is defined as being substantially perpendicular to a direction defined by the longitudinal extension of the CCD-element when arranged in the scanner head.
In one embodiment of the invention the scanning is performed by scanning the alignment area(s) or mark(s) and/or images in bands or stripes. In this embodiment it is preferred that the scanning head is moved in the direction of scanning, while the image may be moved in a direction parallel to the direction of scanning.
It should be understood that the identified area(s) or mark(s) of each image which are selected for alignment can be part of the image itself, but they may also be positioned outside an area covered by the image.
The rotation and/or movement of the image or planar surface is controlled by electronic means, for example by means of a computer or a microcontroller. Similarly, the adjustment performed by moving the scanner head is also controlled by such electronic means.
It should be understood that according to a method of the invention, identifying the alignment area(s) or mark(s) of the first image or determining of the position of the alignment area(s) or mark(s) of the first image may be done manually by a system operator by use of position digitizing means or based on scanned data representing a preview of the first image and associated alignment area(s) or mark(s).
However, when subsequently having scanned alignment area(s) or mark(s) of a second image, the displacement(s) of the alignment mark(s) of the second image may be determined automatically by calculations performed by use of electronic calculation means, for example a computer or a microcontroller, based on scanning data representing the alignment area(s) or mark(s) of the first image and the alignment area(s) or mark(s) of the second image. An example of such an automatic determination routine is given in Example 1.
It is also to be understood that the method described above also can be used when aligning any higher number of images, when each such image has to be aligned to a first image after identification of the alignment area(s) or mark(s) of the first image or after determination of the position of the alignment area(s) or mark(s) of the first image. Thus, it is preferred that three or four images are to be aligned and subsequently scanned, where each such image preferably represents a colour separation of a colour image.
According to one preferred embodiment of the method the film is transparent and is placed between
Dybdal Niels
Ell Søren Christian
Hedegaard Christen
Hemmingsen Hans
Jensen Kim Skovgård
Adams Russell
Eskofot Digital Graphic Systems ApS
Kim Peter B.
Pillsbury & Winthrop LLP
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