Posts Tagged ‘PDF’

Color Measurement the Right Way

Quality printing depends on precise color measurement, which makes it all the more relevant to ask why different measuring devices often produce different results. What should you rely on in this case?

Modern color measuring devices are generally based on spectrophotometers, even if they only show densities. This is because of the higher measuring accuracy of spectrophotometry, together with a greater range of available measurement values. The measuring conditions set on the devices therefore not only need to be selected correctly but must also be identical for all devices. The correct setting often depends on the country. Regional associations such as the bvdm in Germany and CGATS in the United States formerly laid down these conditions. Today they are to be found in the relevant ISO standards. Settings can be made for the following values:

Illuminant: This defines the color temperature of the lighting source. For printing, the standard is currently D50, which corresponds to 5,000 Kelvin.

Observer angle: The standard observer angle in printing is currently defined as 2°. This corresponds to the printer’s observation angle in the matching stage.

Density filter: This determines the spectral range that is to be used to calculate the density values for CMYK. Standards “Status E” (= DIN 16536) and “Status I” (= DIN 16536 NB; narrowband) are usual in Europe. “Status T” is used for measuring in the United States.

Polarization filter: Polarization filters eliminate the gloss of wet ink. The wet values therefore correspond almost entirely to the dry density and tonal values.

White reference: The “absolute white” setting is preferred for density measurement in North America. In all other countries, the white reference is “relative.” Paper white is therefore always taken as the zero point here. To match a spectrophotometer to an old densitometer, it is necessary to know the densitometer’s settings precisely and apply exactly the same parameters to the spectrophotometer. Despite identical settings, minor deviations may occur even within a group of spectrophotometers. These are generally due to the quality and design of the sensor and its calibration. Theoretically, every spectrophotometer should be calibrated to absolute white and black. However, in practice neither one exists, which means it is best to use reference values from an independent institution such as the German Federal Institute for Materials Research (BAM) in Berlin. Manufacturers can have a device calibrated here and use this “master device” to calibrate all other devices. The better the measuring device, the narrower the tolerances that the manufacturer defines for the ΔE and density values. And the smaller the tolerances, the greater the measuring accuracy.

To ensure the measuring accuracy remains constant for as long as possible, users are well advised to have devices serviced and calibrated regularly. Heidelberg is the only press manufacturer to offer a software option – the Prinect Net Profiler – that enables printers to personally calibrate almost all new-generation Prinect color measuring equipment, even including colorimetric calibration. This ensures devices are always close to the factory settings and therefore deliver highly reliable results.

It is also advisable to designate a selected spectrophotometer as the “master” in the print shop itself. This ensures maximum measuring accuracy and, ultimately, print quality across several work stations.

Typical distribution of measuring device deviations – the blue dot in the center is the ideal value for the reference device. The grey circle shows the permitted tolerance. The red dots represent the deviation for different measuring devices.

Source: www.speedmasterunbeatable.com

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History of Color management in operating systems

The most efficient approach is to integrate the color management system into the computer operating system.

Here, every color can be processed neutrally in the computer irrespective of the input or output medium. All the hardware and software components involved in the system can access color management because they all collaborate with the computer operating system.

In April 1993 at the initiative of FOGRA (Forschungsgesellschaft Druck e.V.), several manufacturers of devices and software in the color graphics sector decided to form a committee with the aim of defining and standardizing various cross-platform device profiles for gamut mapping.

The name of this committee is the ICC (International Color Consortium). The ColorSyncR 2.0 system add-on by AppleR, launched onto the market in spring 1995, was the first example of a color management system based on Linotype-HellR/ Heidelberg

technology being implemented in an operating system. The same technology was used at a later date for Microsoft Windows operating systems.

You will find what is known as the Color Matching Module under the term ICM in the operating system under Windows 98, SE, 2000 and XP.

Source:Heidelberg

Pre-flighting is a term used in the printing industry to describe the process of confirming that the digital files required for the printing process are all present, valid, correctly formatted, and of the desired type. The term originates from the pre-flight checklists used by pilots. The term was first used in a presentation at the Color Connections conference in 1990 by consultant Chuck Weger.

Source: everydaycolormanagement.jap

PDF troubleshooter

These are the TOP 10 problems when using PDF in graphic arts. Don’t take my word for it, this list actually comes from Adobe.

  1. The resolution of images is too low.
  2. Fonts are not embedded in the PDF.
  3. The wrong color space is used.
  4. The information about trim or bleed are incorrect.
  5. There is an inconsistency with the native file. The original page, as viewed in QuarkXPress or InDesign or whatever other application looks different from the PDF. Hairlines might be different or gradients have changed.
  6. A spot color is misnamed or it is accidentally converted to a process color.
  7. Images are compressed too much. This causes a quality loss and in some cases artifacts appear inside or around the images.
  8. The page size is incorrect.
  9. There are problems with transparent objects.
  10. ICC profiles are missing or incorrect.

One of the reasons why many of these problems go undetected is that designers have the habit of making proofs from their lay-out, checking those proofs and then creating PDF files. These PDF files don’t get looked at, they are sent straight to the agency or printer. It would be far better if designers created PDF files and then made a proof of these files. This way the consistency between supplied file and proof is much better!

Next to PDF files having some kind of issue, it can of course happen that a PDF cannot be ripped or rendered at all. Here are some typical things to try when this happens:

  1. Use PitStop or another tool to get rid of any irrelevant data in the PDF file. Delete OPI comments, forms, scripts, animations,… and then use ‘Save As’ to create a new clean PDF file.
  2. Refry the PDF file if you don’t have access to the source file(s).
  3. If you have the source files, try recreating the PDF using a different procedure: if the problem file was creating by exporting to PDF, try creating a PostScript file and distilling that. If the problem file was created using Distiller or Normalizer, try using ‘Export to PDF’.
  4. If you have access to the source file: clean it up and recreate the PDF: Make sure that any spot colors that are not printed as spots are converted to CMYK in the original file. Delete any unused data (stuff on the paste board, elements hidden underneath others, unused pages,… )You also may want to merge layers, paths or channels. Then do a ‘Save As’ to create a clean source file.
  5. If everything else fails, try opening the PDF in Photoshop and saving it as an image. This operation converts all text to bitmap so it really has a huge impact on the quality of the output but if everything else fails, this is your last resort.

Source:prepressure.com

PDF VT- VDP

DF/VT is a hot topic these days. In a nutshell, it’s a standard for describing a file format based on PDF, specifically for delivery of jobs for variable data printing. The “VT” part of the name stands for “Variable and Transactional.” It was designed to address all VDP needs, from personalized specialty items, through direct mail, to phone bills and credit card statements.

PDF/VT was published as ISO 16612-2 in 2010, and the first implementations were shown at Ipex in that year, but it took until early 2012 for most of the commonly used document composition vendors to release products that support it. Like many of the other PDFbased standards, PDF/VT uses a file-centric approach. A PDF/VT file encapsulates all of the graphical content for a VDP print job and does so in such a way that an external job ticket can be associated with it to control how it’s processed in the print service provider’s systems. So what benefits does PDF/VT provide? It boils down to four things:

1. Robust content delivery.

PDF/VT builds on nearly two decades of work in CGATS and then in ISO to define the PDF/X standards for the delivery of print jobs. PDF/X-1a, PDF/X-3 and PDF/X-4 are now in common use, but primarily for the delivery of static print jobs. Those standards increase the reliability of printing workflows across multiple companies or sites by requiring that all fonts used are embedded and that all color is specified completely enough to preflight, proof and print correctly. All PDF/VT files must also be valid PDF/X files, so all of the experience encapsulated into those standards is automatically inherited.

2. Integrated data about page ranges.

A PDF/VT file can contain something called a “DPart” structure, which comprises a hierarchy of information about the various pages in a job (this is often called “metadata” because it’s data about data). A specific range of pages may be identified as a personalized catalog for a specific recipient of a direct mail campaign, for example. The next page can be marked as a cover letter to accompany the catalog for the same recipient. At the next level up in the hierarchy, the recipient’s title, address, etc. can be included, pulling all of the printed pieces that must be delivered together. In the level above that, metadata about all recipients within a ZIP code area can be pulled together, and the next level up might show which ZIP codes fall into the area covered by a specific distribute and print service provider site. The hierarchy is designed to be flexible and accommodate whatever data you need in your workflow. It can then be connected with a template-based jobticketing solution to control imposition, rendering, printing, finishing and fulfillment. This can be useful if you’re printing a very large number of relatively short jobs and need a way to ensure that your workflow is correctly configured for each one. But it is most important if you’re printing and fulfilling jobs where each recipient receives different numbers of pages, especially if the output needs to be bound and finishing equipment needs to respond to those differences.

3. Performance optimization hints.

Most rendering workflows designed for VDP include some form of optimization to reduce the amount of processing required for graphical page elements that are used multiple times in a job, so that the rendering process doesn’t slow the press down. Examples might be the background image on a direct mail postcard, the logo or an ad in a TransPromo piece, etc. Each workflow includes its own approach, and these vary in sophistication and effectiveness. Most of them try to render such elements only once, to cache the results of that rendering and then to reuse the cached results multiple times. PDF/VT tries to help in this process by defining some hints that can be written into jobs by the document composition tool as the file is created. These were designed to enable a rendering workflow to identify those reused elements more easily and to therefore make better decisions about caching strategies more quickly. Unfortunately, VDP is a market in which technology is developing so rapidly that the PDF/VT hints are already a little too simple and don’t offer much value to the best current rendering solutions.

4. Support for pseudostreaming.

Historically, data formats defined for transactional printing, such as AFP, have allowed for streaming print workflows, i.e., the first pages of the job can be printed while the composition system is still creating the definitions for later pages. A single PDF file is not well constructed to support streaming (the “optimized PDF” structures to support byte-serving from web sites should not be confused with streaming for print; the requirements are very different). PDF can, however, be used in a “chunking” workflow, where multiple PDF files are created, each containing one chunk of a single job. The first chunk might contain the pages for the first ten thousand recipients of a direct mail piece, for instance, with the next ten thousand recipients in the next chunk. This allows something very close to streaming to be achieved, by printing from one chunk while later chunks are still being written. The efficiency of this mechanism can be improved further by extracting any large shared graphics into a separate PDF file and referring to them from the chunks themselves, so that they only need to be delivered once instead of in every chunk. The PDF/VT standard includes a conformance level called PDF/VT-2, which is specifically designed to support this kind of chunking workflow. It’s even possible to bundle all of the chunks back together into one continuous stream, although that’s more likely to be a good choice for the light production end of the digital production print spectrum than for high-volume printing.

A SOLID FOUNDATION TO BUILD ON

The PDF/VT standard offers some real benefits for the construction of robust, flexible and efficient workflows, encapsulating rendering, printing, finishing and fulfillment. But files must still be constructed well to take advantage of those benefits. It’s important to understand what PDF/ VT offers and what it doesn’t.

Much of what I’ve described above is optional. You can make a perfectly valid PDF/VT file that doesn’t include the DPart structure or optimization hints. It can still be valid even if it’s not constructed in a well-optimized way, even if an image that appears on every page is included separately on every one of those pages, bloating the file and reducing the speed at which it can be processed at the print site. PDF/VT is not the silver bullet that will magically make all your frustrations around VDP print jobs go away, but it is a good foundation that best practice solutions and workflows can be built on.

IT’S BEST TO TEST…

When you’re evaluating a solution for variable data printing, whether it’s on the composition side or on the print site, support for PDF/VT is likely to be a good thing, but there’s no substitute for testing that solution to ensure that it meets your specific needs. At both ends there can also be configuration issues that can have a significant bearing on how efficient the results can be; it’s often worth asking if your vendors have guidelines on best practice and on integration with the other components in your whole workflow.

Martin Bailey is the Chief Technology Officer of Global Graphics Software. He’s also the UK’s principle expert to the PDF and PDF/VT committee in ISO and chaired the CGATS and ISO committees working on PDF/X for many years

PDF Settings Download

Usually we never know what is the right settings for creating a PDF.  Please find below some of the best recommended settings.  Please download and give your feedback.

Download and Install PDF Presets
For use with Adobe Indesign & Illustrator

Download For Mac OS X (10.4 and later)

Download For Windows 2000 / XP / Vista / 7

Note: You only need to import into either INDESIGN or ILLUSTRATOR, it will share the same PDF PRESET.

1. IMPORT PDF PRESET INTO ADOBE INDESIGN

From INDESIGN at the top of the window go to > FILE > ADOBE PDF PRESETS > DEFINE > LOAD > Navigate to the PDF Preset file that you downloaded > HIGHLIGHT PDF PRESET FILE > OPEN > DONE. PDF Preset is now loaded into Adobe Indesign.

TO CREATE PDF FILE FROM INDESIGN

From INDESIGN at the top of the window go to > FILE > ADOBE PRESETS > DUKE PDF > CHOOSE LOCATION TO SAVE PDF TO > SAVE > EXPORT

NOTE: File name should not be any longer than 31 characters including the .pdf extension.

2. IMPORT PDF PRESET INTO ADOBE ILLUSTRATOR

From ILLUSTRATOR at the top of the window go to > EDIT > PDF PRESETS > IMPORT > Navigate to the PDF Preset file that you downloaded > HIGHLIGHT PDF PRESET FILE > OPEN. PDF Preset is now loaded into Adobe Illustrator.

TO CREATE PDF FILE FROM ILLUSTRATOR

From ILLUSTRATOR at the top of the window go to > FILE > SAVE AS > CHOOSE LOCATION TO SAVE FILE TO > GIVE FILE NAME > SAVE AS TYPE > ADOBE PDF > SAVE > SELECT ADOBE PDF PRESET > DUKE PDF > SAVE PDF.

NOTE: File name should not be any longer than 31 characters including the .pdf extension.

4. If you have Adobe Acrobat Distiller and you would like to import the PDF Preset. From ADOBE ACROBAT DISTILLER at the top of the window go to > SETTINGS > ADD ADOBE PDF SETTINGS > Navigate to the PDF Preset file that you downloaded. >HIGHLIGHT PDF PRESET FILE > OPEN. PDF Preset is now loaded into Adobe Acrobat Distiller.

In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium (ICC). Profiles describe the color attributes of a particular device or viewing requirement by defining a mapping between the device source or target color space and a profile connection space (PCS). This PCS is either CIELAB (L*a*b*) or CIEXYZ. Mappings may be specified using tables, to which interpolation is applied, or through a series of parameters for transformations.

Every device that captures or displays color can be profiled. Some manufacturers provide profiles for their products, and there are several products  that allow an end user to generate his or her own color profiles, typically through the use of a tristimulus colorimeter or preferably a spectrophotometer.

The ICC defines the format precisely but does not define algorithms or processing details. This means there is room for variation between different applications and systems that work with ICC profiles. As of 2009, the current version of the specification is 4.2,  but most devices support only version 2.

ICC – International Color Consortium

 Background

A large number of companies and individuals, from a variety of industries, participated in the development of the ICC specification which is designed to provide developers and other interested parties with a clear description of the profile format. A nominal understanding of color science is assumed, such as familiarity with the CIELAB color space, general knowledge of device characterizations, and familiarity of at least one operating system level color management system.

Device profiles provide color management systems with the information necessary to convert color data between native device color spaces and device independent color spaces. The specification divides color devices into three broad classifications: input devices, display devices and output devices. For each device class, a series of base algorithmic models are described which perform the transformation between color spaces. These models provide a range of color quality and performance results which provide different trade-offs in memory footprint, performance and image quality.

The device profiles obtain their openness by using a well-defined reference colour space and by being capable of being interpreted by any ICC operating system or application that is compliant with the specification. In combination with profiles for other devices colour transformations may be determined that enable colours captured on one device to be reproduced satisfactorily on many others. The information required in the profile is adequate to ensure the level of color fidelity selected by the user and for the design of a default color management module (CMM) to transform color information between native device color spaces. Such CMMs are found in many operating systems and applications

In addition to providing a cross-platform standard for the actual profile format, the specification also describes the convention for embedding these profiles within graphics documents and images. Embedded profiles allow users to transparently move color data between different computers, networks and even operating systems without having to worry if the necessary profiles are present on the destination systems. The intention of embedded profiles is to allow the interpretation of the associated color data.

The International Color Consortium Profile Format supports a variety of device-dependent and device-independent color spaces divided into three basic families: 1) CIEXYZ based, 2) RGB based, and 3) CMY based (including CMYK). A subset of the CIEXYZ based spaces are also defined as connection spaces.

More to follow…. Next we will discuss about Rendering intents and Profile connection space