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Studies on image control for better reproduction in offset
KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This research work has focused on studies of image control for better reproduction in offset and has been applied practically. This research work has resulted in a survey of color management knowledge, a communication list concerning ICC profiles, an educational kit, a proposal for a new terminology and a patent concerning image adaptation.

The work is divided into following three areas:

1) image classification

A better understanding of image processing can avoid misunderstandings in the print and leading to more satisfied customers. To achieve optimal print quality for different images, it is important to adapt the prepress settings to the image category. Images can be divided into different categories depending on their image content, key information and tone distribution.

Trials have been carried out in which the IT.8 test chart has been adapted to different image categories. The results of the image adaptation suggest that an adjustment only to low-key images (dark images) is sufficient, as even normal-key images then show a better similarity to the original image. The low-key image showed more details in dark areas.

2) color separation

Two studies has been carried out. The purpose has been to investigate the knowledge level in color separation, the use of ICC-profiles and the understanding of color management in various printing houses in Sweden. This was done to identify and suggest new applications and suggested actions. These studies indicate that there is a serious problem in the graphic arts industry. The problem is that there is both an insufficient knowledge of color management and a lack of communication. There is a lack of competence and a lack of literature and instructions which can help printers to better understand the technology, and communication suffers through a lack of a common language.

3) suggested actions and the development of tools

Terminology simplification is crucial for the users. A new term for separation “Compensation by Black”, CB, has been suggested. A single term should make it easier for the users to understand and use the different settings which impact the image reproduction. A new tool/kit for the evaluation of ICC-profiles has been created. The goal of this educational kit is to facilitate and exemplify the practical understanding of profiles and their use for the users.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , 101 p.
Series
Trita-CSC-A, ISSN 1653-5723 ; 2006:27
National Category
Computer Science
Identifiers
URN: urn:nbn:se:kth:diva-4224ISBN: 978-91-7178-524-4 (print)OAI: oai:DiVA.org:kth-4224DiVA: diva2:11326
Presentation
2006-12-15, E2, KTH, Lindstedsvägen 3, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101112Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-11-12Bibliographically approved
List of papers
1. Image classification and optimized image reproduction
Open this publication in new window or tab >>Image classification and optimized image reproduction
2003 (English)In: TAGA 2003, 2003, 33-36 p.Conference paper, Published paper (Refereed)
Abstract [en]

New adapted color charts have been created based on technical and visual image category analysis. A number of tests have been carried out using extreme images with their key information strictly in dark and light areas. It was shown that the image categorization using the adapted color charts improves the analysis of relevant image information with regard to both the image gradation and the detail reproduction. The images with key information in hi-key areas were also test printed using the adapted color charts.

Keyword
characterization, conversion, ICC, profiling. reproduction
Identifiers
urn:nbn:se:kth:diva-6571 (URN)
Note
QC20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-17Bibliographically approved
2. The characterization of input devices by luminance and chrominance
Open this publication in new window or tab >>The characterization of input devices by luminance and chrominance
2003 (English)In: Polygraficky seminar, 2003, 2003, 10- p.Conference paper, Published paper (Refereed)
Identifiers
urn:nbn:se:kth:diva-6572 (URN)
Note
QC20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-17Bibliographically approved
3. Image reproduction practices
Open this publication in new window or tab >>Image reproduction practices
2004 (English)In: TAGA 2004, 2004, 318-331 p.Conference paper, Published paper (Refereed)
Abstract [en]

Various aspects of image reproduction practices are discussed. The main aim is to simplify image reproduction by implementing a common color language and using a color matching method suitable for the reproduction. To achieve optimized reproduction certain requirements are to be fulfilled mainly knowledge in basic color theory and training in the color reproduction process. Moreover, it is important to have better access to applicable research results in an understandable language and better understanding of available ICC profiling tools and systems on the market.

Keyword
Color; ICC; Management; Problems; Separation
Identifiers
urn:nbn:se:kth:diva-6573 (URN)2-s2.0-23244464407 (Scopus ID)
Note
QC20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-17Bibliographically approved
4. Digital test form for ICC-profiles
Open this publication in new window or tab >>Digital test form for ICC-profiles
2005 (English)In: TAGA 2005, 2005, 454-473 p.Conference paper, Published paper (Refereed)
Abstract [en]

The majority of Swedish offset printers use color management in order to control color reproduction in their daily production. However, there is a lack of understanding of how well the profiles support agreement among color units. Several parameters in the construction and use of a profile affect the final color result. Print production using ICC-profiles demands a better teamwork in the process. The use of non-dedicated printer profiles may cause a less than optimal end-result. Pedagogic color tools can help the user to understand how well a specific profile defines the color gamut of a digital/analogue printingpress. This paper presents an approach to visualizing how well printer profile parameters are defined in the construction of the ICC-profile. The application Adobe Photoshop ® has been used for profile evaluation because of its widespread use in the graphic arts field. A digital test form has been produced consisting of color test targets and images. This digital test form can give information about: 1) differences between color gamuts, e.g. ECl-RGB, ColorMatch 2) total ink coverage 3) the level of achromatic reproduction, GCR, UCR (Gray Component Replacement, Under Color Removal) 4) effect on different tones, e.g. skin tones 5) comparison between different print profiles and the ISO standard - gamut warning 6) gamut mapping 7) different rendering methods 8) chroma shift when converting to CMYK 9) control of gray balance 10) control of color settings in the applications - ProfileMaker and Print Open The basic model is made from a number of color patches forming a uniform matrix pattern. The matrix construction was created in Adobe Illustrator and Adobe Photoshop. The testform is built in the RGB-color mode, using the standardized color working space, ECI-RGB. To achieve an even distribution of lightness and saturation in the matrix, the HSB (Hue, Saturation and Brightness) color model was chosen. Moving from one patch to the next represents a change in saturation and lightness by ten percent. The colors red and cyan, green and magenta, blue and yellow are confronted to each other as a result of their relationship as complement colors. The center point of the model holds a gray scale built from equal amounts of red, green and blue parts in the RGB-mode. The base model contains information about the total ink coverage (%) and control of color cast. Each matrix has been complemented with a color wise corresponding image to enhance the color conversion change. These images have also been divided into a mosaic pattern to enable measurements directly on the images. This digital test form for ICC-profiles has been evaluated by eight independent graphic arts consultants who work with the implementation of ICC-based production. The result of this evaluation is a recommendation for the printers to use this digital test form to increase awareness of the influence of ICC-profiles on the print.

Keyword
Communication; Conversion; Education; ICC; Separation
Identifiers
urn:nbn:se:kth:diva-6574 (URN)
Note
QC20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-17Bibliographically approved
5. Demand specifications for controlled color reproduction
Open this publication in new window or tab >>Demand specifications for controlled color reproduction
2005 (English)In: VII International Seminar in Graphic Arts, 2005, 11- p.Conference paper, Published paper (Refereed)
Identifiers
urn:nbn:se:kth:diva-6575 (URN)
Note
QC20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-17Bibliographically approved
6. Compensation by black: a new separation?
Open this publication in new window or tab >>Compensation by black: a new separation?
2006 (English)In: TAGA 2006, 2006, 193-217 p.Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this paper is to examine the differences between UCR (Under Color Removal) and GCR (Gray Component Replacement) by testing these separation functions in three applications: Adobe Photoshop CS (an image editing application), Gretag Macbeth's Profile Maker 5.0 (profile maker), and Heidelberg's Print Open 4.0.5 (profile maker). A review of the literature pertaining to the different types of separation was made and compiled. An Internet search was also made to check what a prepress employee would find out if he or she was to search for a definition of one of these types of separation. The conclusions of the tests made suggest two alternative proposals and indicate a need to either: 1) Discard the term UCR and use only GCR, as it really only concerns gray component replacement. This would make it easier for people in the business to focus on the process itself instead of trying to understand the difference between the two types of separations, a difference which actually cannot be seen visualy in reality. 2) Discard both terms and introduce a new term CB (Compensation by Black). The software should give the user the possibility of choosing how much black will be used and where it will replace the use of a combination of the CMY process colors. In addition, a single term would make the user more aware of the problems of separation and of how separation will affect the print result. The suggestions imply an extensive review of accepted terms and abbreviations within the graphic arts industry with the aim of giving them a uniform scientific meaning and definition. Thus, it is strongly recommended that the term, CB (Compensation by Black) should be implemented.

Keyword
Compensation; GCR; Separation; UCR
National Category
Media and Communications
Identifiers
urn:nbn:se:kth:diva-6576 (URN)
Conference
58th Annual Technical Conference of the Technical Association of the Graphic Arts, TAGA 2006; Vancouver, BC; 19 March 2006 through 21 March 2006
Note
QC 20100617Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2010-06-29Bibliographically approved
7. Using gray-balance control in press calibration for robust ICC color management in sheet-fed offset
Open this publication in new window or tab >>Using gray-balance control in press calibration for robust ICC color management in sheet-fed offset
2004 (English)In: Proceedings of the Technical Association of the Graphic Arts, TAGA, 2004, 1-20 p.Conference paper, Published paper (Refereed)
Abstract [en]

The use of gray-balance control in press calibration for robust ICC color management in sheet-fed offset is discussed. Gray-balance control is a way to calibrate printing presses. It is found possible to print without a color cast, and still keep print contrast, density, dot gain and CIELAB values for the secondary colors at an acceptable level. It is shown that the ICC profile can give a similar print quality on different papers.

Keyword
Balance, Gray, Offset, Sheetfed, Stability
National Category
Media and Communication Technology
Identifiers
urn:nbn:se:kth:diva-6577 (URN)2-s2.0-23244447404 (Scopus ID)
Conference
56th Annual Technical Conference of the Technical Association of the Graphic Arts, TAGA 2004; San Antonio, TX; United States; 20 April 2004 through 20 April 2004
Note

QC 20100617

Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2014-12-09Bibliographically approved

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Citation style
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Output format
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