digital image formation

Digital Image Formation

Printing Technology

Printing Technology�� Timeline !

1439: Printing Press!1796: Lithography!1903: Offset Printing Press!1907: Screen Printing!1957: Dye-Sublimation!1960’s: Photocopier!1969: Laser Printer!1970: Dot Matrix Printer!1976: Inkjet Printer!

Printing Technology�� Printing Devices

• Dye Sublimation • Inkjet • Laser

• Chemical (Silver Processes)

Printing Technology�� Dye Sublimation Printers

(or dye-sub printer) !

• Employs a printing process that uses heat to transfer dye to a medium such as: !

• plastics, glass, ceramics, printer paper, photographic paper, or fabric.!


• Continuous Tone printing device

• Heat Transfer Process • Creates 24 bit color per pixel by heating & vaporizing the cyan, magenta, yellow, and black dyes in different intensities by varying the heat in 256 levels.

• Uses CMY colors • Cyan, Magenta, Yellow


• Material

• The printing dye is stored/contained on cellophane ribbon and is made up of three color panels.

Dye Sublimation Printers ��

• Advantages • A superior color gamut to inkjet printing

• Prints are dry and ready to handle as soon as they exit the printer • Cost - media packs containing both ribbon and paper yields a fixed cost per print

• The whole printing cycle is extremely clean • no liquid ink / no print heads to get clogged • fewer moving parts that can break down

• Laminate coating to protect print from water • UV coating protects print from UV light damage

Dye Sublimation Printers ��

• Dis-advantages

• Printing Size - only one size pre-printer • Waste - up to 95% of the dye may be wasted for a typical print • Security Risk - a perfect color-separated negative image of the printed page is created on the supply roll color panels

• Last but not least, Dye Sublimation Printers are not good for producing continuous tone Black and White prints.


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Fuji $2495 8” Printer Canon $89.95 6” Printer

Printing Technology�� Ink Jet Printers

•  Propels variably-sized droplets of ink onto the paper surface.!

• Microscopic droplets of cyan, magenta, yellow, and black imitate the color of the pixel.!

• One pixel consists of many small droplets of varying size and color, therefore there is no straightforward relationship between the dots and the pixels of the image!

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Printing Technology�� Ink Jet Printers !!

Printing Technology�� Ink Jet Printers

There are three main technologies in use in contemporary inkjet printers:!

• Thermal

• Piezoelectric

• Continuous!

Printing Technology�� Ink Jet Printers!

Thermal!Canon, HP, Lexmark

!• Uses print cartridges with a series of tiny electrically heated chambers that causes a steam explosion in the chamber to form a bubble, which propels a droplet of ink onto the paper.!

• The ink used is water-based inks using pigments or dyes.!


Piezoelectric!Epson (MicroPiezo)

!• Uses a piezoelectric material in the ink-filled chamber behind each nozzle instead of a heating element.!

When voltage is applied, the piezoelectric material changes shape or size, which generates a pressure pulse forcing a droplet of ink from the nozzle!



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!• Piezo technology allows a wider variety of inks than thermal or continuous ink jet.!

• Print heads are built with robust construction and are designed for high volume production, faster print speeds, and lower costs.!

• The print heads apply between zero to eight droplets of ink per dot and only where needed!


Continuous !

• Continuous ink jet printers are used commercially for printing of products and packages.!

Printing Technology�� Photographic Ink Jet Printers!

Ink Set!


Ink Types!!

• Dye-Base Ink!

• Pigment-Base Ink!


Dye-Based Ink!• Advantages!

• Much stronger than pigment-based ink!

• Can produce more color for a given density!• Dye on the paper is not affected by water or other solvents!

• Keeps reflections even resulting in less Gloss Differential and

Metamerism!


Dye-Based Ink!Disadvantages!!

• Have a tendency to absorb into paper leading to “bleeding” or “dot gain”. !

• Poor Lightfastness resulting in fading prints.!


Pigment-Based Ink!Advantages!

• No Dot Gain, the ink rest on the surface of the paper!• Less ink is needed to create the same intensity of color ! as with dye-based inks!• Pigmented inks offer improved Lightfastness.!

Printing Technology�� Photographic Ink Jet Printers !

Pigment-Based Ink!• Disadvantages!

• Clogging of print heads!• Gloss differential!• Metamerism - ( when two matching color samples do not match when viewed under different light sources or from different angles)!


Inks and Dot Gain!

Printing Technology�� Photographic Ink Jet Printers!!

• Lightfastness!• Is the lifetime of the print without any fading!

• Some paper-ink combinations claim to last 70-200 years.!


• Waterfastness!• Water-resistance!

• Dye-based ink is only water-resistant on specific glossy photo papers!• Pigment-based ink is water-resistant on any paper surface!


• Gloss Differential!• Pigment-based printers: no ink is applied to “white” areas therefore this results in microscopic valleys that can cause non-uniform reflections when viewed from different angles. Also, it can be a problem within different colors. !!

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• Metemerism!• Pigment-based Printers: undesirable colorcast caused by mixing different colors to reproduce shades of gray in a B&W print.!!

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• Image PPI vs. Printer DPI!• Because the printer places many dots (droplets) to represent one pixel the printer’s DPI refers to the amounts of droplets that is printed on the paper and is not directly related to the images PPI/DPI managed in image processing.!


Iris Printer 1987!!

An Iris printer is a large format color inkjet printer manufactured by the Graphic Communications Group of

Eastman Kodak

The prints are noted for their accurate color reproduction.!!

Iris printers have also been used in the production of fine art prints since the early 1990s. An early developer of the

technology in the fine art field was Graham Nash. !!


Iris Printer

• Iris printers use a ‘continuous flow’ ink system to produce continuous-tone output on various media!

• Unlike most ink jet printers which fire drops only when needed, the Iris printers' four 1 micron glass jets flow continuously under high pressure.!

• Drops that are not needed to form the image are deflected electrostatically into a waste system. !

!


GiclÈe pronounced "zhee-clay"

!is an invented name for the process of making fine art

prints from a digital source using archival ink sets and high quality printing paper in a ink-jet printer.!

!

Printing Technology�� Color Laser Printers !

are a common type of computer printer that rapidly produces high quality text and graphics on plain paper!

!Laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is

produced by the direct scanning of a laser beam across the printer's photo-receptor.!

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Printing Technology�� Color Laser Printers

Advantages!!

• CMYK!

• Resolution up to 2400 dpi!

• Speed up to 100 color pages per minute!

• Cost cheaper per volume than any other printer!

!


Disadvantages!!

• Anti-counterfeiting ("secret") marks!• Many modern color laser printers mark printouts by a nearly invisible dot raster, for the purpose of identification!

• Shock hazards!• it is possible for a high voltage or a residual voltage to be present on the various rollers, wires, and metal contacts inside a laser printer!

!


Disadvantages!!

• Toner clean-up!

• Ozone hazards!• the high voltages inside the printer can produce ozone and nitrogen oxides!

!• Respiratory health risks!

• some printers emit sub-micro particles which some suspect may be associated with respiratory diseases!


Disadvantages!

• Media!• Unable to print on coated photographic quality paper!

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