EP0847858B1 - Bande de contrôle visible pour milieux de formation d'images - Google Patents

Bande de contrôle visible pour milieux de formation d'images Download PDF

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Publication number
EP0847858B1
EP0847858B1 EP19970203692 EP97203692A EP0847858B1 EP 0847858 B1 EP0847858 B1 EP 0847858B1 EP 19970203692 EP19970203692 EP 19970203692 EP 97203692 A EP97203692 A EP 97203692A EP 0847858 B1 EP0847858 B1 EP 0847858B1
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EP
European Patent Office
Prior art keywords
control
fields
field
strip
issdv
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EP19970203692
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German (de)
English (en)
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EP0847858A1 (fr
Inventor
Johan Van Hunsel
Jan Van Cauwenberge
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/0036—Devices for scanning or checking the printed matter for quality control
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C11/00—Auxiliary processes in photography
    • G03C11/02—Marking or applying text
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/02—Sensitometric processes, e.g. determining sensitivity, colour sensitivity, gradation, graininess, density; Making sensitometric wedges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
    • B41P2233/00—Arrangements for the operation of printing presses
    • B41P2233/50—Marks on printed material
    • B41P2233/51—Marks on printed material for colour quality control

Definitions

  • the present invention relates to devices and methods for imaging substrates as well as the substrates themselves.
  • the present invention relates to methods and devices for exposure and development of imageable media including photographic film and printing plates.
  • the present invention also includes devices and methods for printing and the printed substrate. More specifically the present invention relates to a visual control strip suitable for quality control of imaging devices and imaged media.
  • control strips As described in US-A-4 852 485, analogue control strips have been used, which consist of a piece of patterned film which could be attached onto a lithographic film before contacting it to a printing plate.
  • CH-A-0 681 929 describes a test "wedge" or control strip which is stored as a digital quantity on a storage medium such as a "floppy disk” or in a computer.
  • the control strip consists of a variety of control fields. Each control field contains a pattern, e.g. a star target, types, a line series, which may contain elements, e.g. checkerboard squares, lines or dots.
  • EP-A-0 518 559 describes a method and apparatus for creating a control strip.
  • a digital representation of the control strip is printed to form a visible, analogue representation of the control strip.
  • the control strip may be printed at the same time as a main coloured image to be reproduced.
  • the control strip consists of control fields and the elements of the control fields can be user defined.
  • PostscriptTM is a programming language created by Adobe Systems Inc., California, USA for defining page, lettering, colour and graphics parameters of images to be output by a raster imaging device such as a printer, an imagesetter or a platesetter.
  • PostScriptTM is described in the "PostScript Language Reference Manual", second edition, Addison-Wesley, 1990 (hereinafter referred to as "AdobeRef”).
  • PostScriptTM files may be incorporated in the file for a main image as an encapsulated PostScript file (EPS file), as described in Appendix H, pages 709-736 in AdobeRef.
  • EPS file encapsulated PostScript file
  • each spot may be influenced by the amount of energy applied to a specific microdot.
  • one ISSDV is the amount of thermal energy locally applied.
  • Standard “originals” are provided in the form of three neutral density (grey) patches : original “A” represents a minimum reproducible density in an average transparency or reflection print, patch “B” is a similar maximum density patch, and patch “M” is a similar medium density patch.
  • original "A” represents a minimum reproducible density in an average transparency or reflection print
  • patch "B” is a similar maximum density patch
  • patch “M” is a similar medium density patch.
  • DE-A-19 507 665 discloses a control strip for visual control consisting of two adjacent longitudinal fields.
  • the first field has large elements, the size of which is substantially independent from illumination variations.
  • the target density of the large elements is position dependent.
  • the second field has fine elements, having substantially the same tone value.
  • the effective tone value depends strongly on the illumination conditions. Although it is possible to assess important illumination variations by this method, it is - due to the arrangement of the different fields - rather difficult to assess accurately small variations in process parameters and to get a quantitative measure for curing the effect.
  • the visual control strip according to the present invention is preferably described as a set of PostScriptTM commands but the invention is not limited thereto. This gives the freedom to incorporate the strip in many printing applications such as computer-to-plate and computer-to-film applications. This strip may even be used in the last stage of making a printing plate or film.
  • the visual control strip in accordance with the present invention is placed at a location on the imageable medium which is imagewise functionally irrelevant.
  • it may be placed on a printing plate at a location which remains ink-free during the subsequent printing process.
  • the present invention also includes a set of visual control strips wherein the target values of the ISSDV (Image Spot Size Deviation Variables) sensitive control fields of the respective strips differ from each other.
  • ISSDV Image Spot Size Deviation Variables
  • three strips may be used with target values for the sensitive fields of 25%, 50% and 75%, respectively.
  • the present invention also includes an imaged medium and a method of assessing imaging quality.
  • “Useful image” in accordance with the present invention refers to the image which is to be recorded on an imageable medium excluding any other images which may be used for control of the imaging process.
  • a "microdot" in accordance with the present invention describes the smallest addressable spatial unit, i.e. portion, of a substrate or medium which can be addressed by an imaging device in order to cause a density change in that unit.
  • a microdot may have any suitable shape such as square, round elliptical etc.
  • optical density In the context of material for visual control, “optical density” is meant. This may be optical density for transmission or reflection of light.
  • the light may be white light or monochrome or monochromatic light.
  • the "light” may also be UV-light or infrared light.
  • density may be meant “lithographic effective” or “ineffective”. By this is meant ink accepting or ink repellant.
  • a “spot” in accordance with the present invention is the smallest actual image which can be produced on an imageable medium by an imaging device.
  • a spot is the result of "rendering” or “marking” a microdot on the medium.
  • a spot is marked by illuminating a portion of the photographic substrate by a suitable amount of light.
  • a spot produced on a photographic substrate is a developed spot.
  • a black or white spot is formed, or, more generally, a spot having a high or low optical density (for reflection or for transmission of light) is formed and/or an ink accepting or an ink repellant spot is formed.
  • the spot produced on a printed substrate is a printed spot.
  • a spot may have any suitable shape such as square, round or elliptical. Usually the centre of a spot has the same location as the centre of a microdot. Each microdot may contain usually one spot. A spot may be larger than its corresponding microdot, i.e. fully cover it, along with portions of neighbouring microdots. A spot may be smaller than its corresponding microdot, i.e. cover only a portion of the microdot. A spot may also partly overlap the corresponding microdot and partly overlap neighbouring microdots.
  • microdots are square and the spots are circular, where the area of the spot equals the area of the microdot and the centre of the spot coincides with the centre of the microdot.
  • a microdot may be left "empty", i.e. no spot is placed in the microdot.
  • the microdot is a fictive area
  • a spot has a low or high density, with respect to its neighbourhood, or it is (gives) either (a) "lithographic effective or ineffective (change)" for a lithographic printing plate, i.e. the spot is ink acceptable or ink repellant.
  • a spot may also have a specific "UV-density" with respect to its neighbourhood.
  • a “dot” in accordance with the present invention is just one spot or a cluster of spots on the imaged medium.
  • a particular type of dot is the "halftone” dot which is a dot including a variable number of spots. The variation of size of the halftone dots is used to reproduce "halftones", i.e. intermediate grey tones between white and black.
  • a halftone dot is formed by just one or a cluster of spots, or by a cluster of absent spots. If the spots are black and the density of the area is low, black spots are clustered in small halftone dots or sparsely distributed halftone dots on a "white" background. For black spots and an area having a high density, the black background is formed by black spots.
  • the halftone dots are the small or sparsely distributed white areas. In that case, the halftone dots are formed by clusters of "non-spots". The size of the halftone dots and/or the distance between neighbouring halftone dots depends upon the grey tone value for the area in which these halftone dots appear.
  • the size of the halftone dots depends on the required grey tone value.
  • the distance between halftone dots depends on the required grey tone value.
  • each microdot may contain at most one spot, it is clear that a halftone dot may also be defined as a cluster of microdots.
  • ISSDV Image Spot Size Deviation Variables
  • image Spot Size Deviation Variables refers to those imaging process variables which influence the size of the spots of the image formed on the imaged medium and which make the spot size deviate from the desired size. It will be understood that the ISSDV also affect dot sizes as each dot may be made up of one or a plurality of spots. However, the influence of the ISSDV on dot size may depend upon dot design and may be considerably different than the influence on a single spot.
  • Fig. 1 is a schematic block diagram of such a system 1.
  • a computer 2 or similar device is used to create a digital representation of an image optionally using a scanner 3 to scan in an image or a store 4 of pre-recorded images which may be accessible optionally via a network 5 such as the Internet.
  • Digital representations of images may be created by graphics software such as Quark XPressTM, Adobe PhotoShopTM, Adobe IllustratorTM, AldusTM PagemakerTM, Corel DrawTM or similar.
  • the digital representation is preferably stored as an output file 6 in a graphics software and output device independent programming language such as PostScriptTM.
  • the output file 6 is transferred to a raster imaging device 10 such as an imagesetter, optionally via a LAN or network 7.
  • a raster imaging device the image is created line by line, i.e. in a raster.
  • an interpreter 8 is provided for conversion (raster image processing) of the output file 6 into an imaging device specific raster data file 9 which can be processed by the raster imaging device 10 by scan conversion.
  • the raster imaging device 10 may include further separate or integrated devices necessary for the development of the imageable medium, e.g. the processor may contain developing and fixing compartments for the photographic film or printing plate.
  • the output of the raster imaging device 10 is an imaged medium 11, e.g. a photographic film or a printing plate.
  • the imaging system 1 may be a computer-to-plate system.
  • a suitable raster imaging device 10 may be a Creo PlateMaster controller linked to a Creo 3244 platesetter with plate conveyor, plate processor and plate stacker all supplied by Creo Products Inc. Burnaby, B.C., Canada.
  • the interpreter 8 may include a Creo Allegro RIP station supplied by the same company compatible with PostScriptTM Level 2.
  • Suitable imageable media may be N90A printing plates provided by Agfa-Gevaert AG, Wiesbaden, Germany or Lithostar LAP-0 printing plates supplied by Agfa-Gevaert N. V., Mortsel, Belgium.
  • the printing plates may be based on a thin metal sheet such as electrochemically roughened and anodized aluminium (most common plate thicknesses are 6 mil, 8 mil and 12 mil, i.e. respectively 0.15 mm, 0.20 mm, 0.30 mm) or have a polymeric base such as polyester.
  • a set of colour separated printing plates e.g. cyan, yellow, magenta or cyan, yellow, magenta and black.
  • the same control strip may be used independent of the colour to be used with the printing plate.
  • a further suitable raster imaging device 10 may be a printer such as an ink jet, thermal transfer or electrostatic printer. Examples are : a DesignJetTM 750C supplied by Hewlett-Packard Corp., USA ; a SummachromeTM Imaging system supplied by Summagraphics Inc., USA ; or a ChromapressTM system supplied by Agfa-Gevaert, N.V., Mortsel, Belgium.
  • a suitable raster imaging device 10 also may be an imager for photographic film such as the SelectSet Avantra 44TM supplied by Bayer Inc., Agfa Division, Wilmington, USA.
  • Imaging devices 10 may be calibrated in accordance with the relevant manufacturer's instructions at regular intervals. Such complex procedures are not suitable for routine production control of imaging quality.
  • the visual control strip in accordance with the present invention has been designed to provide rapid, direct and reliable routine control of imaging quality which can be carried out by untrained personnel.
  • the control in accordance with the present invention may be carried out preferably before the actual printing using the plate starts, while taking up the minimum of space on the imaged substrate.
  • a typical conventional digital raster imaging device 10 records an image on the imageable medium 11 in accordance with a Cartesian array of elements of the image.
  • a microdot or pixel is the smallest addressable spatial unit on the imageable medium 11 of the Cartesian addressing system of the imaging device 10.
  • imagesetter or platesetter it is the fundamental spatial unit which makes up all other graphical structures such as lines or coloured areas.
  • microdots are also called device pixels or RELs (Recorder Elements).
  • the digital raster imaging device 10 When the digital raster imaging device 10 is an imagesetter, it creates an image on medium 11 which after development consists of an array of black, white or coloured spots. If the imageable medium 11 forms a lithographic printing plate, the developed spot on the imageable medium 11 is either ink receptive or ink repellent. When the printing plate is used to print the final image, this final image consists of printed spots, each printed spot corresponding to a developed spot on the medium 11.
  • the developed spot on the imaged medium 11 representing one microdot has a high optical density when illuminated by light, i.e. typically black spots for white light as is well known for so-called "negatives" produced by a conventional camera.
  • the density is a density for spectral UV-light.
  • the optical density of the spot is low when illuminated by light.
  • the illuminated regions become usually ink-repellant.
  • a typical dimension for a microdot on a 400 dpi (dots per inch) printer is 63.5 ⁇ m, and 7 ⁇ m on a 3,600 dpi imagesetter. This means that for a resolution of 3,600 dpi, the imagesetter 10 addresses about 20,000 microdots per mm 2 on the image medium.
  • the present invention is not limited to a certain type of imageable substrate.
  • the spots may be produced by any suitable means, e.g. by heat onto thermally sensitive substrates, by UV or visible or infra-red light onto photosensitive substrates, by application of powders, liquids, inks, pigments or other substances to an appropriate substrate.
  • both heat mode and photo mode systems are known.
  • photo mode materials the image forming reaction is initiated directly by photons having a specific wave length.
  • heat mode materials the image forming reaction is initiated by heat. This heat may be applied directly like in direct thermal printing systems.
  • the heat is applied indirectly via transformation of photons to heat, e.g. via infrared absorbing dyes. This may be achieved by imagesetters having high power infrared laser sources, e.g. from 830 to 1064 nanometre.
  • the imaging device is capable to form one spot on each microdot.
  • the actual size of a spot on a microdot on the imaged medium 11 may vary from the specified size of the microdot depending upon the settings of the imaging device 10 and the nature of the imageable medium. For instance, where the imageable medium 11 is a photographic film, the actual size of the developed spot may depend not only on the exposure and development times but also on the sensitivity and properties of the imageable medium 11.
  • the invention will be described in the following with reference to an imageable medium 11 on which are produced black spots but the invention is not limited thereto. In particular the present invention will be described with reference to an imageable medium 11 for use in an imagesetter 10.
  • the light intensity of the laser beam used in imager 10 varies across its diameter.
  • the intensity of the laser beam reduces towards the outer parts of the laser beam.
  • the light intensity distribution is Gaussian across a circular beam.
  • Each photographic film or plate has a minimum light intensity or threshold value required to create a spot or an image.
  • the developed spot 14 produced by the laser beam of an imagesetter 10 on an imageable medium 11 is shown black but the invention is not limited thereto, the actual developed spot may be in the complementary colour (negative working material) or in the same colour (positive working material) as the colour of the illuminating light.
  • the spot may also be either lithographic effective or ineffective, e.g. ink accepting or ink repellant.
  • the actual spot size 14 on the imaged medium after development alters. With less beam energy the spot size is smaller : compare Fig. 2B with Fig. 2A ; with more energy the spot size increases : compare Fig. 2C with Fig. 2A.
  • the size of the actual spot 14 on the developed medium and hence the grey tone value of each part of the printed image produced there from is dependent upon the exposure parameters, e.g. the sensitivity of the photographic material, exposure intensity and time duration of the laser beam and the developing process used.
  • the printed spot size may differ from the desired microdot size and may depend upon the type of inks used as well as the characteristics of the printed substrate.
  • the printed spot size may depend upon dot gain. Dot-gain is related to spreading of the ink when a dot is printed onto a printing substrate. If this spreading is more than anticipated, the effect of the resulting oversize printed dots is to produce an image with a greater image density than would be expected from the size of the developed spots on the printing substrate.
  • the major factors affecting dot-gain are the thickness of the ink layer on the printing substrate, the physical properties of the ink such as its viscosity and the nature of the substrate surface, e.g. whether it is glossy or matt.
  • Image Spot Size Deviation Variables include the factors mentioned above which may cause variations in image density or spot size because of changes in exposure conditions in an imagesetter, changes in the printing substrate or printing ink in a printer or the different exposure conditions, photographic substrates and developing methods used in photographic reproduction as well as any other variables which affect the image density of a final or intermediate image.
  • One conventional screening or halftoning method consists of grouping the developed or printed spots 14 into halftone dots.
  • a halftone dot is provided by the presence or absence of an array or cluster of developed or printed spots contained within a halftone cell.
  • the halftone cells may themselves be part of a larger organisational unit called a "supercell". It is sufficient to describe a simple halftone dot with reference to Figs. 3A to 3E.
  • Fig. 3A shows a Cartesian array 16 of microdots representing a part of an image to be recorded on imageable medium 11. Where the imaging device 10 is an imagesetter, it is pre-programmed to illuminate each of the individual square elements 12 (i.e.
  • the imager traverses the array 16 line-by-line or column-by-column.
  • the direction of traverse is known as the fast-scan direction and the direction perpendicular thereto the cross-scan direction.
  • the imaging device is a printer, it is adapted to print a printed spot 14 in each of the square elements 12 or to leave it blank depending upon the image to be printed. In the following we will describe the invention with respect to an imagesetter but the invention is not limited thereto. Similar principles also apply when the imaging device 10 is a printer or other digital imaging device.
  • Each 8 x 8 matrix of microdots 12 shown in Figs. 3B to 3E is organised as a halftone cell 13.
  • the portion of the original image that is represented by a given halftone cell 13 has a certain spatially integrated grey tone value.
  • the relevant microdots 12 of the corresponding cell 13 on the imageable medium 11 are illuminated with the laser light so as to create the right number of spots 14 to produce the right grey tone value, e.g. a light tone such as shown in Fig. 3C, a darker tone such as in Fig. 3D or nearly black as in Fig. 3E.
  • the "dot percentage" is given by the ratio of :
  • ABS is used with a 45° screen angle
  • an imaginary line joining two corresponding spots in two neighbouring cells lies at 45° to the vertical axis of the cell, this angle being known as the screen angle.
  • the frequency of such lines, expressed in lines per inch, is called the screen ruling.
  • An alternative screening or halftoning method is the stochastic or frequency modulated (FM) method for representing grey tones by binary output systems.
  • FM frequency modulated
  • this method is the number of fixed-sized halftone dots in a particular area which determines the grey value, i.e. the spatial frequency of the halftone dots determines the grey value.
  • the distribution of dots is random or quasi-random as shown in Fig. 4A and they are not organised into touching clusters except by chance when the grey tone value approaches mid-grey to black values.
  • the number of fixed-sized dots in a particular area may determine the grey tone value, wherein each dot may include several spots.
  • An example of a frequency modulated screening method is the CristalRasterTM technology provided by Agfa-Gevaert, N.V., Mortsel, Belgium.
  • a suitable FM screening method in accordance with the present invention may be quasi-random.
  • the sequence of filling the arrays of microdots forming the halftone cell 13 is regular but is designed to achieve the same effect as a random distribution of spots, i.e. regularly growing clusters are not formed.
  • Such a sequence of filling the halftone dot 15 is shown in Fig 4B which represents an 8x4 cell 13 having 32 microdots. The numbers refer to the filling sequence of the halftone cell 13.
  • the halftone cell 13 When no element of the 8x4-array is black, the halftone cell 13 is purely white. When all 32 elements of the halftone cell 13 are black, the result is purely black.
  • the intermediate tones are produced by making the relevant number of elements black. There is no growth of regularly sized dots with increasing grey tone value. Instead, the clusters of spots remain small and separated from each other and their number rather than their size increases as the grey tone value increases.
  • the halftone dot size may be fixed for low densities and the mean distance between halftone dots may be variable to increase the density or grey tone value, whereas the dot size may be increased to further increase the grey tone value.
  • ISSDV Image Spot Size Deviation Variables
  • the change in diameter would therefore be the same quantitative amount as for a single spot.
  • a 20x20 cluster of spots is substantially more insensitive to the Image Spot Size Deviation Variables (ISSDV).
  • a 4x4 cluster is therefore more sensitive to the Image Spot Size Deviation Variables (ISSDV) than a 20x20 cluster.
  • FM screening preferentially only uses individual fixed size spots or small clusters of spots, so that a change in spot size on the imaged medium 11 has a considerable effect on the grey tone value of the final image. It is particularly important for FM screening methods to be able to set up the imager 10 correctly and also to monitor the quality of imager, photographic film or printing plate performance regularly, accurately and easily.
  • the visual control strip according to the present invention achieves this aim.
  • a visual control strip 20 in accordance with the present invention is shown schematically in Figs. 5A to 5C at different exposure levels when the visual control strip has been formed on an imaged medium 11.
  • the strip 20 may be imaged onto a photographic printing plate or photographic film 11 by imager 10.
  • strip 20 may be a strip recorded on photographic film which is imaged onto the medium 11 by contact exposure as is conventional in the manufacture of lithographic plates.
  • the visual control strip 20 comprises a plurality of control fields 30 to 38 relatively insensitive to the Image Spot Size Deviation Variables (ISSDV) and a background field 39 relatively sensitive to the Image Spot Size Deviation Variables (ISSDV).
  • an alpha-numerical field 40 is also provided above or below the control fields 30 to 39.
  • the ISSDV insensitive control fields 30-38 are arranged in such a way as to ease the visual comparison with the ISSDV sensitive background field 39. That advantage is achieved by improving the contact between the sensitive and the insensitive zones.
  • One embodiment is shown in Fig. 5A, 5B and 5C.
  • the insensitive fields 30-38 are completely surrounded by the sensitive field 39.
  • the insensitive fields 30-38 have a shape of a circle segment, whereas the sensitive field 39 is surrounding completely the insensitive fields.
  • the circular sensitive fields 39 are surrounded by the insensitive fields, having stepped dot percentage values.
  • Figure 8B is a comparitive example very similar to the prior art control strip according to DE-A-19 507 665.
  • Fig. 8C shows also a comparitve example, where the sensitive fields 39 are pair-wise enclosed by insensitive fields 30-38.
  • the outer dimensions of the digital control strip 20 are typically 12 mm or more preferably 10 mm or less in width.
  • Each ISSDV insensitive control field 30 to 38 has a different grey tone value.
  • the grey tone value of each control field 30 to 38 is also substantially independent of, or at least only marginally dependent upon the Image Spot Size Deviation Variables within wide limits. This independence can be achieved by correct choice of the elements which make up fields 30 to 38, e.g. they may be certain types of coarse checkerboard patterns or patterns created with an AM screening method of a low screen ruling.
  • the background 39 is provided by a field whose grey tone value is more sensitive to the Image Spot Size Deviation Variables (ISSDV).
  • ISSDV sensitive background field 39 may be a field created using a stochastic or frequency modulated screening method built up by small halftone dots, each halftone dot formed by one spot or a few spots.
  • field 39 may include a fine checkerboard pattern.
  • the ISSDV sensitivity of the background 39 is normally (default value) set to at least the ISSDV sensitivity of the screening method used for the useful image to be placed on the medium 11.
  • the sensitive field 39 would be preferably a 50% raster field of this type.
  • the default sensitive field 39 could be, for example, a 4x4 checkerboard field or a 50% raster field of the ABS type having the same screen ruling as the screen ruling used for the useful image.
  • the ratio of sensitivities of the ISSDV insensitive control fields 30-38 and the ISSDV sensitive background field 39 is relevant to the correct functioning of the visual control strip 20 in accordance with the present invention. Absolute values of sensitivity are less relevant provided the sensitive and insensitive fields behave in a consistent fashion with respect to the Image Spot Size Deviation Variables. For small deviations in spot size, the change in area "A" of a spot is proportional to its perimeter "P" (see Fig. 2D). Hence, the ratio of
  • the ratio of sensitivities is 0.25.
  • this ratio of sensitivity is preferably less than 0.35, more preferably less than 0.25 and most preferably less than 0.125.
  • High sensitive fields may be formed by :
  • the ISSDV insensitive control fields 30 to 38 may have regularly spaced dot percentages or grey tone values, e.g. 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% which are associated with the numerical reference values of -4 to +4 in the alpha-numerical field 40.
  • Field 39 may be designed to have a target grey tone value of 50%.
  • Figs. 5A under ideal conditions, with the imager 10 perfectly calibrated to the film 11, the field 34 annotated with "0" is indistinguishable from the background 39.
  • Figs. 5B and 5C show the situation where the medium exposure is not properly set. In Fig.
  • the background 39 has been produced so much darker than a tone value of 50%, that the field 36, annotated with"+2", is indistinguishable from the background 39 rather than the field 34 annotated with "0".
  • the background field 39 is lighter than a grey tone value of 50% so that the field 32, annotated with "-2”, is indistinguishable from the background 39.
  • more ISSDV insensitive control fields 30 to 38 may be provided with a corresponding smaller grey tone value difference between neighbouring fields.
  • the grey tone values of the ISSDV insensitive control fields 30 to 38 are not simply a linear or regular scale of grey tones but rather they are linked to the differentiated well-defined sizes of the actual spots on the imaged medium after development which are responsible for the generation of the different grey tone values.
  • the numerical values of the alpha-numerical field 40 may be directly related to the effect of a specific change in size of the spot.
  • field 32 which has the numerical value "-2”
  • field 32 which has the numerical value "-2”
  • "+4" which corresponds to the ISSDV insensitive field 38, may indicate that field 38 has a grey tone value equal to the grey tone value produced on field 39 when the spot size on the medium after development is 4 micron larger than the spot required to produce the grey tone value of the field 34 annotated with the numeral "0".
  • the adjustments to the imager 10 may be carried out more easily.
  • inputs to the imager 10 of the number in field 40 corresponding to the control field 30-38 which is indistinguishable over the background field 39 may be processed by suitable logic circuits in imager 10 and result in an automated exposure adjustment.
  • the present invention is not limited to a grey tone target value of 50% for the background field 39, but other values may be chosen.
  • the ISSDV insensitive fields 30 to 38 are determined for each strip 21 to 23 so that each field 34 of the relevant strip 21-23 annotated with the numeral "0" has the respective grey tone target value, i.e. for strip 21, the respective field 34 annotated with the numeral "0" has a grey tone value of 25% ; for strip 22, it has the value 50% and 75% for strip 23.
  • the ISSDV insensitive fields 30-38 and the sensitive field 39 are not limited to a linear array as shown in Figs. 5 and 6.
  • the fields may be arranged in any suitable two dimensional array.
  • the ISSDV insensitive fields 30 to 38 may be arranged radially on an ISSDV sensitive background 39. Due to the familiarity among operators with analogue clock faces, such an arrangement can be used easily when formed into twelve equally spaced radial fields around 360° thus forming a "grey tone clock".
  • Such a clock may have particularly small dimensions, e.g. the dimension of a small wrist watch such as 15 mm x 15 mm.
  • the numerical field 40 can be dispensed with or left away as the operator can read the "hours" 1 to 12 of the "clock” without numbers to help. The operator does not have to be capable to read the - often very small - arabic figures of the "hours".
  • the present invention is not limited to foreground fields 30 to 38 (Fig 5A-5C) being the ISSDV insensitive fields.
  • a comparative embodiment is shown in Fig. 8A.
  • Control strip 24 has a series of background fields 30 to 38 which have differing grey tone values, the pattern of each field 30-38 being substantially insensitive to the Image Spot Size Deviation Variables (ISSDV).
  • Fields 39 which are sensitive to the Image Spot Size Deviation Variables are each located as a foreground field in one of the background fields 30 to 38.
  • Each field 39 has a target grey tone value as described previously, e.g. 25%, 50% or 75% or similar.
  • the ISSDV sensitive fields 30 to 38 and insensitive fields 39 are arranged one above the other as shown in a comparative example of Fig. 8B or alternating with each other as shown in Fig. 8C.
  • the insensitive fields may take discrete (as shown in Fig. 8A, 8B and 8C) or continuously varying values.
  • the ISSDV sensitive field 39 may be a checkerboard field, a pixel line field, or a raster field.
  • the ISSDV insensitive fields 30-38 of the control strip 20 in accordance with the present invention may also each be a checkerboard field, a pixel line field, or a raster field, however, it is preferred if the raster field is not produced with an FM screening method having small halftone dots made up of one or only a few spots.
  • Figs. 9 to 11 show a checkerboard
  • Figs. 10A and B show pixel line fields
  • Figs. 11A and B show raster fields.
  • Each of these fields includes one or more microdots.
  • dots, lines or fill are made up of an array of microdots.
  • Each dot, line or fill constitutes an element.
  • a plurality of elements makes a pattern. The elements may make up a pattern with a repetitive pattern cell which is tiled in order to fill up the area of the relevant control field 30-39.
  • the control field 30-39 may include a series of lines or larger dots arranged in a predetermined pattern.
  • One larger dot preferably comprises an integer number of microdots or spots.
  • the visual control strip 20-24 in accordance with the present invention is a digital control strip
  • it is preferably scalable.
  • Scalability refers to the ability of the digital control strip to be transformed, i.e. resized to a different physical size, e.g. smaller or larger in one or two dimensions.
  • the strip is designed such that the integrity of the pattern within the fields is maintained. This means that scaling has no influence on the number of spots in an element of a pattern, nor on the relative location of the spots.
  • the outer dimensions of a field are altered differently in two orthogonal directions, the field is deformed but the elements within the field are not deformed. The undeformed elements fill the deformed field - if the field has become smaller, the number of elements in the field reduces.
  • Device space is the internal co-ordinate system used by the raster imaging device 10 for scan conversion of the raster data file 9 and is usually expressed or "measured" in "pixel” units.
  • User space is the internal co-ordinate system used to create the output file 6 in the device independent language such as PostScriptTM and is usually expressed in metric units such as 1/72 of an inch (see AdobeRef, page 151) or millimetre.
  • a current transform matrix CTM may be used (see AdobeRef, 4.3.2 Transformations, pages 152-154).
  • This matrix converts the data in the output file 6 into data in raster data file 9 taking into account any difference in resolution between the co-ordinate systems of the user space (the device independent language) and the device space (raster imaging device 10).
  • a distance of X units in the user space defined in output file 6 is converted by the CTM into the appropriate number of pixels Y in the device space which result in the same distance in device space as is represented by X units in the user space.
  • the distance produced by the imaging device 10 is independent of the resolution of the imaging device 10.
  • X distance units of device space defined in output file 6 result in X distance units in device space.
  • the actual size, in metric units, of elements defined in the device space is device dependent - the size depends on the number of dpi (microdots per inch) of the imaging device 10. For instance, the device space distance X printed by a 300 dpi printer would 10 times greater than by a 3000 dpi printer. In general, specifying data in device space is discouraged as the appearance of the data is device dependent and may seem to be deformed relative to user space.
  • control fields 30-39 are preferentially defined in device space, whereas the dimensions of a control field in accordance with the present invention may be defined in user space.
  • Control fields 30-39 are preferably scalable and their size may be defined by the user. Depending on its size, a control field 30-39 is filled up with as many elements as required, the elements being clipped at the boundaries of the control field.
  • the pattern elements are defined in device space, their actual size on the imaged substrate is dependent on the resolution of the imaging device. On the other hand the size of the field itself is set by the user.
  • a control field 30-39 according to the present invention may be generated in PostScriptTM in the following manner with reference to Figs. 10A and B :
  • This program listing fragment defines a pattern "OnePixelLinesVer" which is 8x1 pixels in a matrix of 8x8 pixels in device space.
  • the pattern consists of a vertical line 47 (Fig. 10A or B) having a thickness of one microdot or pixel in the device space.
  • the pattern is defined in an 8x8 matrix so that the line width may be amended to be up to 8 pixels in thickness in other fields.
  • the repetition distance between two matrices, X_StepL is defined in user space (not listed above) so this repetition distance is output device independent.
  • the complete field is defined in user space : 0 0 X_fieldY_field 1.0 /PixelLinesVer setpattern rectfill which generates a field of the required size which is filled by the pattern OnePixelLinesVer and is clipped at the boundaries of the field.
  • the field is scalable in user space without altering or deforming the pattern of the element OnePixelLinesVer which is defined in device space.
  • the pixel line 47 may be a black line surrounded by white or vice-versa.
  • pixel line fields are used, their performance may depend upon whether the lines lie parallel or perpendicular to the fast scan direction in the imager 10.
  • pixel lines which are orthogonal to each other, i.e. to have part of the control field with vertical lines and part with horizontal lines.
  • the above script may be amended to create alternating, XxX black and white squares in the 8x8 matrix 46 (Fig. 9).
  • the distance X_StepL is not defined.
  • the 8x8 matrix is specified as the pattern cell and tiled within the field 30-39 by means of the rectfill command. This generates a pattern of black and white, for example 4x4 device pixel squares whose size is device dependent and non-scalable (see Fig. 9).
  • the field (30-39) dimensions are specified in user space using scalable dimensions.
  • Fig. 9 shows a checkerboard field in accordance with the present invention.
  • Figs.11A and B show schematic representations of a raster field.
  • Each halftone cell contains one halftone dot 48. This results in a regular array of dots 48 in lines at the screening angle.
  • the grey tone value is determined by the size of the halftone dot 48.
  • a raster field may be formed by white dots on a black background.
  • the ISSDV sensitive fields 39 may be generated using uniform grey tone fields having stochastic or FM screening methods such as the Agfa CristalRasterTM technology provided by Agfa-Gevaert, N.V., Mortsel, Belgium or other types of ISSDV sensitive screening methods such as the Bayer halftone screening method mentioned above.
  • ISSDV sensitive screening methods such as the Bayer halftone screening method mentioned above.
  • checkerboard, pixel line or raster fields may be used which are characterised by a relatively large perimeter "P" per unit surface "A” (see Fig. 2D).
  • a correspondence table may be produced as shown in Table 1 below.
  • the values have been calculated for an output device 10 with a resolution of 2,400 dpi and a sensitive control field 39 having a checkerboard pattern of 4x4.
  • the dot gain "x" in Table 1 refers to the increase (+x) or decrease (-x) in the radius of the spot over the specified value for the field "0" of the control strip 20 of Fig. 5A, i.e for a theoretical 50% dot percentage.
  • a 50% dot percentage is realised by defining a square supercell having two square halftone dots.
  • the length and width or size of the supercell is 8 microdots.
  • the size of each halftone dot is 4 microdots.
  • the first microdot is located in the top left corner of the supercell.
  • the second microdot is located in the bottom right corner of the supercell. As such, both microdots touch each other at a corner point situated right in the middle of the supercell.
  • each spot fills exactly one microdot.
  • Two such square halftone dots are placed in a supercell, composed of 8X8 microdots.
  • Table 1 may be used when the ISSDV sensitive field has a 4x4 checkerboard pattern.
  • the dot percentages of the ISSDV insensitive fields are preferably set to the grey tone values corresponding to the theoretical values of the "y" column caused by the dot gain of -5 to +5 micron of the basic spot. If the visual control strip shows correspondence at "-2" (corresponding to -2 ⁇ m dot gain of the basic spot) between the ISSDV insensitive and sensitive fields, then the image produced by the imager 10 at 50% dot percentage has an effective grey tone value of about 41% instead of 50%. From this converted value of achieved grey tone value, the necessary adjustments to the imager 10 can be made.
  • the screen ruling of the sensitive fields is the same as the screen ruling of the useful image data. The screen ruling of the insensitive fields is usually smaller.
  • table 1 may be used to control the degree of over- or under-exposure.
  • the degree of under exposure may be selected form the table and the imager 10 set up to accordingly.
  • the visual control strips 20-24 (Fig. 5, 6, 7) in accordance with the present invention may be used in the following way.
  • the visual control strip is a digital control strip
  • the digital representation of the strip 20-24 is incorporated into a digital representation of a normal page in the computer 2 as, for instance, an EPS file.
  • This file may be imaged directly onto a printing plate.
  • the control strip is preferably located in an image-wise functionally irrelevant part of the page layout.
  • the control strip may be located in an area of the plate which is outside the zone to be inked.
  • An imaged offset printing plate 90 is shown schematically in Fig.
  • Printing press location or registration holes 92 may be provided. Within the confines of the location holes 92, an inkable area 93 is defined. It is within this area 93 that the normal pages or graphic images have been imaged onto the plate 90.
  • securing the printing plate 90 to the plate cylinder as e.g. described in US-A-4 643 093 as but one example (plate securing on web offset presses).
  • the inkable area 93 will be subjected to the ink rollers.
  • a perimeter area 94 which is not inked and serves no image-wise purpose. This area has the mechanical function of locating and securing the plate to the press but has no function with respect to the reproduction of the image itself, i.e. no image-wise functionality. It is in this area 94 that one or more of the control strips 20-24 in accordance with the present invention may preferably be placed. It is particularly preferred if the control strip 20-24 of the present invention, is placed in the plate portion of zone 94 which is received in the plate locking or clamping device of the printing plate cylinder.
  • control strip 20-24 in accordance with the present invention is preferably scalable, it can be fitted to the available space in ink-free zone 94. Because the field elements are preferably not scalable, they remain suitable for quality control purposes independently of the size of the fields, provided these are each greater than a minimum size of preferably 2 mm.
  • the type of field e.g. checkerboard, pixel line, raster field, the type of screening method and the screen angle are set for both the ISSDV sensitive and insensitive fields as well as the target value(s) of the sensitive field(s) in accordance with default values.
  • the operator can alternatively select any of these variables from a menu to tailor the visual control strip 20-24 to the needs of a particular job.
  • the visual control strip 20-24 in accordance with the present invention is an analogue strip for use in photomechanical screening or contact illumination
  • the strip may be used in the following way.
  • the visual control strip 20-24 comprises a piece of film which can be included in the page layout film. Again this piece of film including the visual control strip 20-24 is preferably located on a part of the layout film that lies outside the useful printable and inkable area of the printing plate produced from the layout film.
  • the visual control strip 20-25 in accordance with the present invention has been described with reference to a plurality of ISSDV relatively insensitive fields and a single ISSDV relatively sensitive field but the invention is not limited thereto.
  • the visual control strip in accordance with the present invention also includes a single ISSDV relatively insensitive field 39 and a plurality of ISSDV relatively sensitive fields 30 to 38 (the visual control strip would still appear as shown in Figs. 5 to 7 but the sensitive fields would be insensitive and vice-versa).
  • the relative sensitive fields 30 to 38 could each have differing grey tone value target values, e.g. 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% ; and the insensitive field could have a grey tone value of 25% or 50% or 75%.
  • the simplest form of visual control strip 20-25 in accordance with the present invention is a single ISSDV relative insensitive field located adjacent to, or surrounded by a single ISSDV relative sensitive field or vice-versa.
  • Such a visual control strip can be used to identify when the pre-determined grey tone value of the ISSDV relative insensitive field is the same as the target grey tone value of the ISSDV relative sensitive field.
  • Fig. 13 shows comparative example of a control strip in which a single ISSDV relative sensitive field 51 is located adjacent to a plurality of ISSDV relative insensitive fields 52.
  • the sensitive field 51 represents a 50% grey tint and is screened according to the Agfa CristalRaster technology, a type of frequency modulated halftoning.
  • the size of a frequency modulated halftone dot is 21 ⁇ m.
  • the insensitive fields 52 have a dot percentage of 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% and 75%. These are screened according to the Agfa Balanced Screening (ABS) technology, as disclosed in US-A-5,155,599.
  • the line ruling of the ABS screen is 120 lpi (lines per inch). Due to the shorter outline with respect to the area of each halftone dot in the ABS screening at 120 lpi, the fields 52 are less sensitive to overexposure and underexposure.
  • FIG. 14 shows another test strip and shows a sensitive field 53, having the same structure as the sensitive field 51 ; and insensitive fields 54, having the same structure and dot percentages as the insensitive fields 52.
  • the insensitive fields 54 are completely and separately embedded in the sensitive field 53
  • the insensitive fields 52 are arranged adjacent to each other and are also placed adjacent, i.e. underneath, to the sensitive field 51.
  • a series of exposures were accomplished with both control strips according to Fig. 13 and Fig. 14.
  • Log H of subsequent exposures increased by 0.05 from exposure to exposure.
  • Two types of offset printing plates were exposed :
  • the exposed offset plates were offered to five test persons for identification of the control strips having a correct exposure. All five test persons preferred this evaluation on the control strip according to Fig. 14, where the insensitive fields 54 are completely surrounded by the sensitive field 53. Evaluation of the correct exposure on the strip according to Fig. 14 is more convenient, fast and accurate than evaluation on the strip according to Fig. 13.
  • the circular regions 54 shown in Fig. 14 tend to disappear in the background 53 when there is a correspondence of the circular region 54 with the background 53. In Fig. 13, a border line between fields 51 and 52 is perceived, even where the insensitive field 52 corresponds to the sensitive field 51, due to optical illusion. Accordingly, evaluation of the correct exposure of a control strip according to Fig. 14 is more consistent and less subjective than evaluation of the exposure of a control strip according to Fig. 13.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)

Claims (12)

  1. Bande de contrôle visuel. (20) destinée à être reproduite, par un processus de reproduction, sur un support imageable (11) tel qu'une plaque d'impression (90), un film photographique ou un substrat d'impression, comprenant
    une pluralité de premiers champs de contrôle (30-38), chacun présentant un premier pourcentage de points, différent de celui d'un autre premier champ de contrôle ;
    au moins un deuxième champ de contrôle (39), immédiatement adjacent auxdits premiers champs de contrôle, présentant au moins une deuxième valeur de pourcentage de points uniforme, ladite deuxième valeur de pourcentage de points uniforme étant essentiellement égale à l'une desdites premières valeurs de pourcentage de points des premiers champs de contrôle (30-38) ;
    dans laquelle lesdits premiers champs de contrôle (30-38) sont, du fait du contenu des champs de contrôle, moins sensibles aux Variables d'écart de taille des spots d'image (Image Spot Size Deviation Variables, ISSDV) du processus de reproduction, influençant la taille des spots de la bande de contrôle (20) reproduite, que lesdits deuxièmes champs de contrôle (39), ceux-ci étant plus sensibles aux Variables d'écart de taille des spots d'image (ISSDV) ;
    caractérisée en ce que lesdits premiers champs de contrôle (30-38) sont complètement entourés par l'un desdits deuxièmes champs de contrôle (39).
  2. Bande de contrôle visuel (20) selon la revendication 1, dans laquelle au moins un desdits premiers champs de contrôle moins sensibles (30-38) ou desdits deuxièmes champs de contrôle plus sensibles (39) comporte l'un quelconque parmi un champ de trame, un champ de lignes de pixels ou un champ en damier.
  3. Bande de contrôle visuel (20) selon l'une quelconque des revendications précédentes, dans laquelle la sensibilité aux ISSDV dudit premier champ de contrôle moins sensible (30-38) est de préférence moins du tiers, plus préférablement moins du quart et le plus préférablement moins du huitième de la sensibilité aux ISSDV dudit deuxième champ de contrôle plus sensible (39).
  4. Bande de contrôle visuel (20) selon l'une quelconque des revendications 2 à 3, dans laquelle les valeurs de pourcentage de points de la pluralité de premiers champs de contrôle moins sensibles (30-38) sont liées à une séquence ascendante régulière de tailles de spots pour ledit deuxième champ de contrôle plus sensible (39), la séquence ayant de préférence un intervalle de tailles de spots constant entre des tailles de spots.
  5. Bande de contrôle visuel (20) selon l'une quelconque des revendications précédentes, dans laquelle ladite bande de contrôle visuel (20) est une bande de contrôlé numérique, et chaque premier (30-38) ou deuxième (39) champ de contrôle comporte au moins un élément, chaque dit élément n'étant pas dimensionnable et chaque dit champ de contrôle étant dimensionnable indépendamment desdits éléments.
  6. Bande de contrôle visuel (20) selon la revendication 5, dans laquelle :
    la représentation de la bande de contrôle numérique est stockée dans un langage indépendant du dispositif de sortie ;
    lesdits éléments sont définis dans l'espace du dispositif de sortie ; et,
    lesdits champs sont définis dans l'espace de l'utilisateur.
  7. Pluralité de bandes de contrôle visuel (21, 22, 23) selon l'une quelconque des revendications précédentes, dans laquelle :
    ledit deuxième champ de contrôle plus sensible (39) d'au moins une bande de contrôle visuel (21, 22, 23) présente une deuxième valeur de pourcentage de points différente de la deuxième valeur de pourcentage de points de tout autre deuxième champ de contrôle (39) de toute autre bande de contrôle visuel (21, 22, 23).
  8. Support imagé (11) comportant au moins une bande de contrôle visuel selon l'une quelconque des revendications précédentes, située de préférence dans une partie du support imagé (11) non pertinente du point de vue de l'image.
  9. Support imagé (11) selon la revendication 8, dans lequel le support imagé (11) est une plaque d'impression (90) pour une presse d'impression, et la partie non pertinente du point de vue de l'image peut être située dans le dispositif de verrouillage de la presse d'impression.
  10. Procédé d'évaluation de la qualité de formation des images dans un système de formation d'images à l'aide d'une bande de contrôle visuel (20) conformément à l'une quelconque des revendications 1 à 8.
  11. Procédé selon la revendication 10, dans lequel le système de formation d'images est :
    un système pour produire des plaques d'impression imagées ; ou,
    un système du type ordinateur à la plaque.
  12. Appareil destiné à générer une bande de contrôle visuel (20) sur un support imageable (11) tel qu'une plaque d'impression, un film photographique ou un substrat d'impression, ledit appareil comprenant :
    un moyen servant à générer une pluralité de premiers champs de contrôle (30-38) ;
    chacun présentant une première valeur de pourcentage de points différente de celle d'un autre premier champ de contrôle ;
    relativement moins sensibles à des Variables d'écart de taille des spots d'image (Image Spot Size Deviation Variables, ISSDV) ;
    et,
    un moyen servant à générer au moins un deuxième champ de contrôle (39) ;
    relativement plus sensible auxdites Variables d'écart de taille des spots d'image (ISSDV) ;
    immédiatement adjacent auxdits premiers champs de contrôle (30-38) insensibles aux ISSDV ; et,
    présentant une deuxième valeur de pourcentage de points, ladite deuxième valeur de pourcentage de points étant essentiellement égale à l'une desdites premières valeurs de pourcentage de points ;
    caractérisé en ce qu'il comprend un moyen servant à générer lesdits premiers champs de contrôle (30-38) complètement entourés dudit deuxième champ de contrôle.
EP19970203692 1996-12-11 1997-11-25 Bande de contrôle visible pour milieux de formation d'images Expired - Lifetime EP0847858B1 (fr)

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SE9903174D0 (sv) * 1999-09-08 1999-09-08 Skogsind Tekn Foskningsinst Test-printing method and test-printing form for use in the method
DE10143942A1 (de) * 2001-09-07 2003-03-27 Wifag Maschf Prüfmittel und Verfahren zur Kontrolle des Offset- und Digitaldrucks
DE10312457A1 (de) * 2003-03-20 2004-09-30 Fogra Forschungsgesellschaft Druck E.V. Verfahren zur Bestimmung der auf einem Trägermaterial erzielten Pixelgröße eines Schreibstrahls sowie dessen Verwendung zur Bestimmung des absoluten Tonwerts
JP2004333875A (ja) * 2003-05-08 2004-11-25 Fuji Photo Film Co Ltd 平版印刷版の画像評価方法及び品質管理方法
DE102006011140A1 (de) * 2006-03-10 2007-09-13 Heidelberger Druckmaschinen Ag Prozesskontrollstreifen und Verfahren zur Aufzeichnung
DE102007028327A1 (de) * 2007-06-15 2008-12-18 Flexicon Ag Druckanlage sowie Verfahren zum Bedrucken von Druckträgern
DE102007029211A1 (de) * 2007-06-25 2009-01-08 Heidelberger Druckmaschinen Ag Verbesserter Druckkontrollstreifen zur Farbmessung auf Bedruckstoffen
CN102615958A (zh) * 2012-03-20 2012-08-01 辅讯光电工业（苏州）有限公司 导光板、印刷模板和导光板制造及检测方法
DE102013010970A1 (de) 2013-07-01 2015-01-08 Heidelberger Druckmaschinen Ag Speziell gerastertes Graumessfeld

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EP0196431B1 (fr) * 1985-03-21 1992-11-11 Felix Brunner Procédé, dispositif de réglage et moyens auxiliaires pour l'obtention d'un résultat d'impression uniforme au moyen d'une machine d'impression offset polychrome fonctionnant suivant le procédé de similigravure
DE3830121A1 (de) * 1988-09-05 1990-03-15 Felix Brunner Verfahren und vorrichtung zur einstellung eines vorgegebenen, durch ein wertepaar volltondichte/rasterpunktaenderung definierten druckstandards bei einem autotypischen druckvorgang
CH681929A5 (en) * 1990-06-08 1993-06-15 Ugra Verein Zur Foerderung Wis Quality control testing of printing processes - uses test pattern consisting of mixt. of line dot and chess board patterns
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