This is an insightful blog post about the problem with paper in terms of published standards
Typically paper - the most used printing substrate - accounts for some 30-50 percent of the overall print project cost. And despite the fact that it is also often the most expensive component of the final presswork it's surprising that there are no published standards, specifications or trade customs in the paper industry.
The assignment of a particular grade to a quality category and the establishment of sales policies are made by each paper mill based on its own internal evaluation of its products relative to those of its competitors. That makes direct, objective, competitive comparisons between different papers virtually impossible.
The color of paper is identified using adjectives like "cream","natural", "white", etc. rather than objective definitions such as the CIEL*a*b* coordinates that printers use. Again, there are no specifications or tolerances provided by mills as to the consistency of a specific paper color either through the stack, roll, or when the same brand is supplied by mills located in different regions.
The brightness of the sheet is one common measure of distinction. It is measured by comparing the amount of light reflected by the paper surface to the amount of the same light reflected by the surface of magnesium oxide established as the standard of 100%. A common term used in quoting the measure is “G.E. brightness,” although G.E. no longer manufactures the measuring instrument. "Brightness" is also not a measurement that printers or buyers can measure themselves. Even though variation is part of every manufacturing process, there are no defined tolerances for paper brightness.
There are no specifications or tolerances or even notification of optical brightener agent content. This has become a major issue as the mills have mostly switched from clay fillers to calcium carbonate. This problem has resulted in the fact that papers today, for the most part, no longer meet the ISO 12647 specification. Papers with optical brighteners are impossible to visually match between printing technologies which can cause severe disconnects between proof and presswork as well as greater color shifting as presswork and proof are viewed under different lighting conditions.
"Caliper" defines the thickness of paper, measured in thousandths of an inch, which can also be expressed as a point size - e.g. If the caliper of a paper measures .009 inches it is a "9 point" stock. As paper caliper varies, presswork color may also vary. But again there are no defined tolerances for paper caliper either through the stack, roll, or across the width or length of the sheet.
Source: qualityinprint.blogspot.com
Monday, 17 October 2011
What is design for print? Stock considerations
Following on from this post, I decided to look at paper stock in more depth.
Paper density
The paper density of a type of paper or cardboard is the mass of the product per unit of area. The term density here is not used in its traditional sense of mass per unit volume. "Paper density", rather, is a measure of the area density. Paper products that let little or no light pass through (e.g. poster board) are considered dense or heavy. Paper products that allow some light to pass through (e.g. tissue paper) are considered lightweight.
In the metric system, the density of all types of paper and paperboard is expressed in terms of grams per square metre (g/m²). Typical office paper has 80 g/m², therefore a typical A4 sheet (1⁄16 m²) weighs 5 g. The unofficial unit symbol "gsm" instead of the standard "g/m²" is also widely encountered in English speaking countries.
Moo business cards
"We love paper as much we love print. We never settle for second best and we don’t see why you should either. There’s no sneaky hidden charges for ‘better’ paper, because 'better paper' is MOO’s standard paper."
Source: uk.moo.com
Weight: 350gsm
Finish: Matte Laminate, silky, faintly reflective.
Print quality: Crisp white, reproduces colour well.
Production: Sourced from sustainable forests. Elemental Chlorine free.
Which means: Choose this thick stock for its great print quality and smooth satin feel.
Weight: 352gsm
Finish: A light coating, non reflective
Print quality: Unflecked, equally good for art or photograph
Production: 100% recycled and recyclable. Manufactured using wind power. Free from harmful chemicals.
Paper density
The paper density of a type of paper or cardboard is the mass of the product per unit of area. The term density here is not used in its traditional sense of mass per unit volume. "Paper density", rather, is a measure of the area density. Paper products that let little or no light pass through (e.g. poster board) are considered dense or heavy. Paper products that allow some light to pass through (e.g. tissue paper) are considered lightweight.
In the metric system, the density of all types of paper and paperboard is expressed in terms of grams per square metre (g/m²). Typical office paper has 80 g/m², therefore a typical A4 sheet (1⁄16 m²) weighs 5 g. The unofficial unit symbol "gsm" instead of the standard "g/m²" is also widely encountered in English speaking countries.
Moo business cards
"We love paper as much we love print. We never settle for second best and we don’t see why you should either. There’s no sneaky hidden charges for ‘better’ paper, because 'better paper' is MOO’s standard paper."
Source: uk.moo.com
Weight: 350gsm
Finish: Matte Laminate, silky, faintly reflective.
Print quality: Crisp white, reproduces colour well.
Production: Sourced from sustainable forests. Elemental Chlorine free.
Which means: Choose this thick stock for its great print quality and smooth satin feel.
Weight: 352gsm
Finish: A light coating, non reflective
Print quality: Unflecked, equally good for art or photograph
Production: 100% recycled and recyclable. Manufactured using wind power. Free from harmful chemicals.
What is design for print? Paper sizes/formats
In the ISO paper size system, the height-to-width ratio of all pages is the square root of two (1.4142 : 1). In other words, the width and the height of a page relate to each other like the side and the diagonal of a square. This aspect ratio is especially convenient for a paper size. If you put two such pages next to each other, or equivalently cut one parallel to its shorter side into two equal pieces, then the resulting page will have again the same width/height ratio.
The ISO paper sizes are based on the metric system. The square-root-of-two ratio does not permit both the height and width of the pages to be nicely rounded metric lengths. Therefore, the area of the pages has been defined to have round metric values. As paper is usually specified in g/m≤, this simplifies calculation of the mass of a document if the format and number of pages are known.
The ISO paper sizes are based on the metric system. The square-root-of-two ratio does not permit both the height and width of the pages to be nicely rounded metric lengths. Therefore, the area of the pages has been defined to have round metric values. As paper is usually specified in g/m≤, this simplifies calculation of the mass of a document if the format and number of pages are known.
ISO A Series
ISO B Series
The B series formats are geometric means between the A series format with the same number and the A series format with one lower number. For example, B1 is a geometric mean between A1 and A0. The sides of B0 are 1 m to v2 m.
ISO Size variations
ISO Envelope sizes
This envelope series was designed to accommodate ISO A size papers. Metric measurements are the finished envelope size. Inch measurements are approximate (calculated at 25.4 mm = 1 inch and rounded off). Although DL is not part of the ISO C series, it is a very widely used standard size. DL, probably at one time the abbreviation of DIN Lang (Deutsche Industrie Norm, Long), is now identified as "Dimension Lengthwise" by ISO 269.
What is design for print? Colour management
CMYK
The CMYK color model (process color, four color) is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key (black). Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation.
Process colour is generally very good for reproducing pictures but there are some colours that it cannot reproduce well. This is because the gamut (or range) of reproducible color for Process Colour is not as wide as that of RGB color. As a result, certain intense values of colors such as Orange, Green, Blue, and other bright colours can sometimes appear dull or even dirty. On the other hand, bright Reds generally reproduce very well.
RGB
Digital cameras and scanners and create images using combinations of just three colors: Red, Green and Blue (RGB). These are the primary colors of visible light and this how computers and televisions display images on their screens. RGB colors often appear brighter and more vivid specifically because the light is being projected directly into the eyes of the viewer.
This is an "additive" process in which the three colors are combined in different amounts to produce various colors. It is called "additive" because you must add varying amounts of two or more colors to achieve hues and values other than the three basic red, green and blue colors. Computer monitors and televisions vary the amount of each color from 0 to a maximum of 255. Equal maximum amounts of all three colors (often expressed as R255, G255, B255) creates white. The absence of all three colors (R0, G0, B0) creates black. Equal amounts of all three colors somewhere between 0 and 255 will create varying shades of gray.
Source: bestprintingonline.com
Adobe Kuler
Explore colour themes: Browse thousands of color themes created by the Kuler community. Search by tag word, title, creator, or hex color.
Create colour themes: Quickly create themes with the easy-to-use tools in Kuler. Use the color wheel, harmony rules, and color sliders for ultimate customization. You can also upload an image which you are then able to select colours from, forming the basis of a complimentary colour scheme - useful for editorial pieces.
The CMYK color model (process color, four color) is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key (black). Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation.
Process colour is generally very good for reproducing pictures but there are some colours that it cannot reproduce well. This is because the gamut (or range) of reproducible color for Process Colour is not as wide as that of RGB color. As a result, certain intense values of colors such as Orange, Green, Blue, and other bright colours can sometimes appear dull or even dirty. On the other hand, bright Reds generally reproduce very well.
Since RGB and CMYK spaces are both device-dependent spaces, there is no simple or general conversion formula that converts between them. Conversions are generally done through color management systems, using color profiles that describe the spaces being converted. Nevertheless, the conversions cannot be exact, particularly where these spaces have different gamuts (as seen below):
The Gamut Warning tool in Photoshop allows you to see what colour are out of the CMYK gamut range. Before converting an RGB image to CMYK, it is useful to use various image adjustments beforehand to achieve similar colours.
Digital cameras and scanners and create images using combinations of just three colors: Red, Green and Blue (RGB). These are the primary colors of visible light and this how computers and televisions display images on their screens. RGB colors often appear brighter and more vivid specifically because the light is being projected directly into the eyes of the viewer.
This is an "additive" process in which the three colors are combined in different amounts to produce various colors. It is called "additive" because you must add varying amounts of two or more colors to achieve hues and values other than the three basic red, green and blue colors. Computer monitors and televisions vary the amount of each color from 0 to a maximum of 255. Equal maximum amounts of all three colors (often expressed as R255, G255, B255) creates white. The absence of all three colors (R0, G0, B0) creates black. Equal amounts of all three colors somewhere between 0 and 255 will create varying shades of gray.
Source: bestprintingonline.com
Adobe Kuler
Explore colour themes: Browse thousands of color themes created by the Kuler community. Search by tag word, title, creator, or hex color.
Create colour themes: Quickly create themes with the easy-to-use tools in Kuler. Use the color wheel, harmony rules, and color sliders for ultimate customization. You can also upload an image which you are then able to select colours from, forming the basis of a complimentary colour scheme - useful for editorial pieces.
What is design for print? Rich black
On a computer monitor, there is only one way to represent black. When there is no light coming from the monitor, the screen is black. In print there are many different ways to represent black.
The simplest is "plain black," or 100% black ink (0C, 0M, 0Y, 100K). However, you can also create a "rich black" by printing other inks along with black. There are many different possible ink combinations - the most common "rich black" contains percentages of all 4 inks: 63C, 52M, 51Y 100K. This particular variant owes it's popularity to Adobe Photoshop - when an RGB file is converted to CMYK, areas that are absolute RGB black (R0, G0, B0) will wind up with this combination, unless certain default settings have been changed. Other possible flavors of "rich black" are "Cool Black" (60C, 0M, 0Y, 100K) and "Warm Black" (0C, 60M, 30C, 100K).
The problem with all these blacks is that they all look the same on the computer screen - all of them are represented as R0, G0, B0 - but they will not look the same on paper. A classic beginner's mistake is to take a photoshop image that fades into rich black on all sides, place it in a picture box in the page layout software, and assign the picture box a background of "black" ("black" in page layout software = plain black). This appears to be continuous and uniform on the computer screen. If the layout were to be printed, however, there would be a distinct difference between the areas of rich black and plain black.
The solution to this problem is to measure the ink values in the CMYK (referencing Photoshop's info palette), and create a matching color in the page layout program. Care must be taken that the rich black in the CMYK image is actually continuous; move the cursor around and make sure that the ink values don't fluctuate. Then create a new separated CMYK color in Quark using the Edit>Colors dialog box; you can call it "Rich Black." Assign that color to the background of the picture box. Check your work by printing paper separations before sending out for film. The special-purpose color "registration" is another potential source of black mismatches. On screen, by default, it appears as R0, G0, B0, so it seems as if it might be the same as black. It's not. Registration color prints 100% on all plates. If your layout is CMYK, then registration color is 100C, 100M, 100Y, 100K.
If your layout is CMYK + Pantone 285, then registration color is 100C, 100M, 100Y, 100K, 100Pantone 285. Registration color is used for, appropriately enough, registration marks, explained elsewhere. Do not use it in place of black. Having that much ink go down presents many problems from a printing standpoint. There's no good reason to use anything other than Plain Black or a Rich Black variant.
Source: printernational.org
The simplest is "plain black," or 100% black ink (0C, 0M, 0Y, 100K). However, you can also create a "rich black" by printing other inks along with black. There are many different possible ink combinations - the most common "rich black" contains percentages of all 4 inks: 63C, 52M, 51Y 100K. This particular variant owes it's popularity to Adobe Photoshop - when an RGB file is converted to CMYK, areas that are absolute RGB black (R0, G0, B0) will wind up with this combination, unless certain default settings have been changed. Other possible flavors of "rich black" are "Cool Black" (60C, 0M, 0Y, 100K) and "Warm Black" (0C, 60M, 30C, 100K).
The problem with all these blacks is that they all look the same on the computer screen - all of them are represented as R0, G0, B0 - but they will not look the same on paper. A classic beginner's mistake is to take a photoshop image that fades into rich black on all sides, place it in a picture box in the page layout software, and assign the picture box a background of "black" ("black" in page layout software = plain black). This appears to be continuous and uniform on the computer screen. If the layout were to be printed, however, there would be a distinct difference between the areas of rich black and plain black.
The solution to this problem is to measure the ink values in the CMYK (referencing Photoshop's info palette), and create a matching color in the page layout program. Care must be taken that the rich black in the CMYK image is actually continuous; move the cursor around and make sure that the ink values don't fluctuate. Then create a new separated CMYK color in Quark using the Edit>Colors dialog box; you can call it "Rich Black." Assign that color to the background of the picture box. Check your work by printing paper separations before sending out for film. The special-purpose color "registration" is another potential source of black mismatches. On screen, by default, it appears as R0, G0, B0, so it seems as if it might be the same as black. It's not. Registration color prints 100% on all plates. If your layout is CMYK, then registration color is 100C, 100M, 100Y, 100K.
If your layout is CMYK + Pantone 285, then registration color is 100C, 100M, 100Y, 100K, 100Pantone 285. Registration color is used for, appropriately enough, registration marks, explained elsewhere. Do not use it in place of black. Having that much ink go down presents many problems from a printing standpoint. There's no good reason to use anything other than Plain Black or a Rich Black variant.
Source: printernational.org
What is design for print? File types
We routinely use various file formats for saving, opening, and printing files. But questions persist in many minds about whether the file formats they’ve chosen are in fact appropriate for their print workflow. Are the specific options they selected when saving their files the right ones? Are there other choices that improve the quality of their artwork or output?
Raster and vector Raster art, also called bitmapped art, is comprised of a grid of colored pixels that make up the image. Scanners, digital cameras, screen capture applications, and paint programs generate and save raster art. Vector art is comprised of mathematically defined objects with specific shape parameters like arcs, circles, and squares. CAD (Computer-Aided Design) programs and drawing and illustration packages produce this kind of art.
Tip #1 In Photoshop you can save a copy of the file in its present state while continuing to work on the original file. To do this, check the Save: As a Copy option in the Save As dialog. This is similar to photocopying a document and filing it away for future use, while continuing to work on the original.
I might as well say this upfront: The main file formats used for print work actually do not alter or improve the image data and appearance in any way. They merely control how the file is written to disk. But how a file is written will affect how the file is handled by the application that opens it. A key question: Is the application merely to open the art and print it, or will you be editing, cropping, scaling, and manipulating the art as well? Why different file formats? Most file formats are made to handle a specific kind of artwork, typically either vector or raster art. Luckily, in the print world, recommended file formats handle both kinds of artwork very well. So how do you know which format to use, and when?
It gets a bit confusing when we realize that mainstay applications such as Photoshop, Illustrator, InDesign, and QuarkXPress can use raster as well as vector art. So to exchange files between these applications, you should use “standard” formats that can contain any kind of artwork for saving and opening across applications and platforms. The main players in this category are the TIFF, EPS, and PDF formats. Each uses the exact same image data but writes the file with specific permissions and limitations for editing and manipulating the file content in applications.
When to use what format?
Although you might create and archive artwork in its originating application in its “native” format such as PSD, AI, etc., you might also want to save a copy of the file to send to a client or offsite for output. The Save As option in the File menu allows you to save a copy of the file in one of the standard formats. Save As also allows you to rename the file, flatten layers, simplify artwork, reduce the file size, and remove any extras such as annotations, paths, etc. See Tip #1.
Learning standard formats
Each of the standard formats was designed to fulfill a certain need and has unique advantages in certain conditions and workflows.
TIFF (Tagged Image File Format) TIFF is an industry standard designed for the handling of raster or bitmapped images. It can save black-and-white (1-bit), grayscale, index color (256 color), RGB, LAB, and CMYK images. It supports 8 bits/channel and 16 bits/channel files, and various forms of compression. Saving in TIFF means that you can save or embed an ICC color space profile in the file, making it the format of choice in a colormanaged workflow. In other words, just about any application that can read bitmapped art will open TIFF files. The attractive aspect of TIFF files is that once placed in a program, you can edit, scale, and manipulate all aspects of the artwork!
A CMYK TIFF file will often print faster than another format because of the way the image data is sent to the printer. TIFFs offer a variety of file compression options, including the excellent “lossless” (nondegrading to image quality) LZW compression. Photoshop users can also compress files using lossless ZIP compression, and for higher compression rates and more compact file sizes they can choose “lossy” (degrading to image quality) JPEG compression. In Photoshop CS, the TIFF format will save layers, adjustment layers, and spot colors, though at present these files can be read by very few applications. If you encounter a problem opening a Photoshop TIFF file in a layout program, you’ll need to reopen the file in Photoshop. Choose Save As from the File Menu, check Save: As a Copy, then uncheck any checked boxes pertaining to Alpha Channels, Layers, Annotations, and Spot Colors. Choose TIFF and click Save.
Raster and vector Raster art, also called bitmapped art, is comprised of a grid of colored pixels that make up the image. Scanners, digital cameras, screen capture applications, and paint programs generate and save raster art. Vector art is comprised of mathematically defined objects with specific shape parameters like arcs, circles, and squares. CAD (Computer-Aided Design) programs and drawing and illustration packages produce this kind of art.
Tip #1 In Photoshop you can save a copy of the file in its present state while continuing to work on the original file. To do this, check the Save: As a Copy option in the Save As dialog. This is similar to photocopying a document and filing it away for future use, while continuing to work on the original.
I might as well say this upfront: The main file formats used for print work actually do not alter or improve the image data and appearance in any way. They merely control how the file is written to disk. But how a file is written will affect how the file is handled by the application that opens it. A key question: Is the application merely to open the art and print it, or will you be editing, cropping, scaling, and manipulating the art as well? Why different file formats? Most file formats are made to handle a specific kind of artwork, typically either vector or raster art. Luckily, in the print world, recommended file formats handle both kinds of artwork very well. So how do you know which format to use, and when?
It gets a bit confusing when we realize that mainstay applications such as Photoshop, Illustrator, InDesign, and QuarkXPress can use raster as well as vector art. So to exchange files between these applications, you should use “standard” formats that can contain any kind of artwork for saving and opening across applications and platforms. The main players in this category are the TIFF, EPS, and PDF formats. Each uses the exact same image data but writes the file with specific permissions and limitations for editing and manipulating the file content in applications.
When to use what format?
Although you might create and archive artwork in its originating application in its “native” format such as PSD, AI, etc., you might also want to save a copy of the file to send to a client or offsite for output. The Save As option in the File menu allows you to save a copy of the file in one of the standard formats. Save As also allows you to rename the file, flatten layers, simplify artwork, reduce the file size, and remove any extras such as annotations, paths, etc. See Tip #1.
Learning standard formats
Each of the standard formats was designed to fulfill a certain need and has unique advantages in certain conditions and workflows.
TIFF (Tagged Image File Format) TIFF is an industry standard designed for the handling of raster or bitmapped images. It can save black-and-white (1-bit), grayscale, index color (256 color), RGB, LAB, and CMYK images. It supports 8 bits/channel and 16 bits/channel files, and various forms of compression. Saving in TIFF means that you can save or embed an ICC color space profile in the file, making it the format of choice in a colormanaged workflow. In other words, just about any application that can read bitmapped art will open TIFF files. The attractive aspect of TIFF files is that once placed in a program, you can edit, scale, and manipulate all aspects of the artwork!
A CMYK TIFF file will often print faster than another format because of the way the image data is sent to the printer. TIFFs offer a variety of file compression options, including the excellent “lossless” (nondegrading to image quality) LZW compression. Photoshop users can also compress files using lossless ZIP compression, and for higher compression rates and more compact file sizes they can choose “lossy” (degrading to image quality) JPEG compression. In Photoshop CS, the TIFF format will save layers, adjustment layers, and spot colors, though at present these files can be read by very few applications. If you encounter a problem opening a Photoshop TIFF file in a layout program, you’ll need to reopen the file in Photoshop. Choose Save As from the File Menu, check Save: As a Copy, then uncheck any checked boxes pertaining to Alpha Channels, Layers, Annotations, and Spot Colors. Choose TIFF and click Save.
What is design for print? Imposition
Imposition
(Wikipedia) Imposition is one of the fundamental steps in the prepress printing process. It consists in the arrangement of the printed product’s pages on the printer’s sheet, in order to obtain faster printing, simplified binding and less waste of paper. Correct imposition minimizes printing time by maximizing the number of pages per impression, reducing cost of press time and materials. To achieve this, the printed sheet must be filled as fully as possible.
Imposition can be affected by the following:
(Wikipedia) Imposition is one of the fundamental steps in the prepress printing process. It consists in the arrangement of the printed product’s pages on the printer’s sheet, in order to obtain faster printing, simplified binding and less waste of paper. Correct imposition minimizes printing time by maximizing the number of pages per impression, reducing cost of press time and materials. To achieve this, the printed sheet must be filled as fully as possible.
Imposition can be affected by the following:
- Format of the product: The size of the finished page determines how many pages can be printed on a single sheet.
- Number of pages of the printed product: The compositor must determine how many sheets are to be printed to create a finished book.
- Stitching/binding method: The compositor must understand how the sheets are placed to form the signatures that compose the finished book.
- Paper fiber direction: Many papers have a "grain," reflecting the alignment of the paper fibers. That these fibers must run lengthwise along the fold influences the alignment, hence the position, of the pages on the printed sheet.
- Finishing and binding
Imposition Software carries out the most important task in the printing industry. Print operators will print books using huge sheets of paper, to be folded later. This allows for faster printing and lower production costs. Imposition is the process of arranging pages correctly prior to printing so that they fold in the correct order. To someone unfamiliar with the imposition process, the pages may seem to be arranged randomly; but after printing, the paper is folded, bound and trimmed. If correctly imposed, the pages should all appear in the correct orientation and readable sequence.
Imposition dummy
An imposition dummy should be created in order to envision how the pages relate to one another.
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