AUSMEDIA.COM.AU

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AUSMEDIA.COM.AU

• Russell Martyn
• 442 Station St, Box Hill
• 1800 00 88 99

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Colour

• Colour vision is made possible by the presence of
  cones located in the centre of the retina
• 3 types of CONES receptors
• Red, Green Blue
• light of a given hue (wavelength) falling onto
  the retina will be converted to an
  electrical signal which the brain
  interprets as a colour.

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• We say "interprets" because colour perception is
  based on the physical wavelength of the light
  plus a psychological response based on adjacent
  colours. This is why it is best to choose a
  boring grey background when evaluating colours.

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Colour Management Why What Is it?

• Colour management is necessary because our human
  eyes are pretty amazing.
• If scanners, monitors and printers could scan,
  display and print the entire range of colours
  which the human eye can see, we wouldn't need
  colour management.
• Colour management is a fudge to make up for the
  fact that each device has different limits and
  deals with colour in a different way. Each device
  has its own "colour space", which defines which
  colours are within its range and how it deals
  with those colours.

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Additive Colour Model

• Monitors produce color by shooting Red, Green and
  Blue guns onto a black screen.

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Subtractive Colour Model

• Printers use  Cyan, Magenta and Yellow inks  on
  white paper to produce color

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Colour Models

• The difference between the two Colour Models is
  based on how color is produced.
• "RGB" is "Projected Light" and
• "CMYK" is "Reflected Light"

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RGB    Imagine using stage lights with
different color filters on them, projected onto
the stage at the theater.As more light is added,
regardless of color, the stage will become washed
out in white light.

• Combining varying amounts of Red, Green and Blue
  will faithfully create a "spectrum" of
  colours.And it is the varying amounts of red,
  green and blue projected onto the phosphors of a
  monitor or television screen that bring the
  world to our homes.

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RGB 

• Red, Green and Blue primary colours display color
  based on the "Additive Colour Model".
• This gives them the name of Additive Primary
  Colours".

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C,M,Y,K - reflective

• The sun shines white light on something, and a
  part of the spectrum is absorbed by it.The rest
  of the light is reflected back into your eye.The
  color you perceive is based on the "Subtractive
  Colour Model".
• Painting red colour onto white paper will absorb
  the blue and green of the spectrum of light
  shining onto the paper.But if yellow paint is
  added overtop in the hope of creating orange, it
  can be disappointing when brown is seen instead.
• Put simply The more painted, the darker it gets!
• Knowing that pigments added to paper will darken
  it, using very selective light colours will
  faithfully create a spectrum of colour.

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• Cyan will absorb red, Magenta will absorb green
  and Yellow will absorb blue.These are called the
  "Subtractive Primary Colours", also known as
  "Secondary Colours".
• Because of the lightness of Cyan, Magenta and
  Yellow, BlacK is used for the gray
  components,and to save on printer
  cartridges!(The letter K is used to avoid
  confusion, because B might also stand for blue.) 
  
• Printing with these inks to reproduce color is
  called Four Colour Process Printing. 

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Looking at a basic sweep of the spectrum, where
the primary colors overlap the secondaries are
created. Cyan between blue and green. and Yellow
between green and red.

• Where's the Magenta?
• Here's a bit of trivia "Magenta" doesn't exist
  within the spectrum! You won't see it in a
  rainbow either.

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• By taking this "linear" spectrum and looping it
  back around we can get the Magenta.
• And by filling in the circle, the "Color Wheel"
  is created.
• Any point of color is measured as a degree
  between 0 and 360 on the Color Wheel.
• As all the colors converge in the center it
  creates a "White Point".

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• Scanners and digital cameras all work in RGB
  mode and so does a monitor.
• But the printer uses CMYK

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• The colours that are reproducible by any device
  are limited to the color model they use. 
• And frequently you will see messages posted to
  tech support forums or lists asking  "Why
  doesn't it look the same when it prints?"
• One reason comes back to "You have colors that
  are out of gamut".

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• So what's a Gamut?
• Gamut range. The printer's "colour gamut" is
  simply the range of colours it can print.
•  

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From here the data is plotted onto a graph, and
this step is a science in itself!    The way it
is accomplished is by making a model of the color
spectrum and displaying it 3 dimensionally

• The actual measurements of visible light
  wavelengths are illustrated below.

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• In this simple example the 'Colour Wheel' makes
  up the X and Y axes.
• The Z axis, 'Luminance', determines how dark or
  light the colour is.
• For example, the "Red Bar" with more Luminance
  added would be Pink.. 

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• This wireframe grid represents the simple model
  of visible light as imagined in 3D space. 
• This would be called a 'Color Space' 
• The top point would represent pure white  and
  the bottom point absolute black.
• More specifically, this would be a rude rendition
  of an "HSL" color space

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• Any possible color can therefore be defined
  numerically! 
• In 1993 the International Colour Consortium (ICC)
  was established to provide a standardised
  solution which would ensure that colour fidelity
  is maintained in a predictable way between
  different input and output devices.

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Colour Space

• a computer file which describes how a certain
  specific device deals with colour in certain
  circumstances

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Where does this leave us?
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• Photo taken with Canon film camera
• using Fuji colour negative film.
• Developed in Kodak chemicals.
• Scanned with a Nikon film scanner.
• Displayed on a Mitsubishi Cathode Ray Tube (CRT)
  monitor.
• Printed on an Epson printer using Epson inks and
  Epson paper.

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Our Goal !

• to make prints with colours which look the same
  as the ones we saw when we originally took the
  photo.
• By the time the print comes through that range of
  devices and products, there is only one thing
  which is going to keep the colours looking like
  they did on the day, and that's the
  photographer's eye for colour

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Lets keep it simple!
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Adobe Gamma using the eye

• Step by step assistant
• 1st pick an existing profile for a starting point
  - colour sync system profile ORAny profile you
  believe is more accurate
• 2nd Brightness and Contrast (black squares)
• 3rd Choosing Phosphors (check manual)
• 4th Setting the Gamma standard Mac gamma is 1.8
  but many are calibrating to 2.2 (De-check view
  single gamma only to allow you to adjust the red,
  green and blue individually)

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Setting the white point

• 6500K daylight is generally the best
• 5000K is a standard viewing point it tends to be
  too yellow on a monitor
• 9300K great for general computer use but it is
  too blue to match white paper
• Adjusted white point choose same as hardware
  almost there

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Adobe Gamma cont.

• Next screen will allow you to compare your
  monitor before and after the calibration
• Should only see a small shift in the midtones
• Otherwise start again and check each step
  carefully
• FINALLY you should save the profile (date it!!!)
• NOTE OSX does not use Adobe Gamma it uses the
  ColourSync calibration assistant and its monitor
  profile is saved in Library-gtColour-gtProfiles
  at a user level
• On Mac OS9 you should save it in the coloursyn
  profiles folder (at the root level of the system
  folder).
• This way it will always appear as one of your
  colour settings options

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Monitor Spyders

• Individual Colour Guns

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Working Space - device independent

• AdobeRGB1998 perceptually uniform, grey balanced
  and wide enough gammut for all CMYK or RGB output
  devices
• AppleRGB default colour space of Photoshop 2.0
  great if you wont to simulate a Photoshop 4 or
  earlier workspace
• ColorMatch RGB based on a discontinued monitor
  space known as Radius Pressview. Slightly
  smaller than AdobeRGB1998 and tends to clip cyan
  and orange.
• SRGB was the default RGB space in Photoshop 5.0
  Designed by Hewlett-Packard and Microsoft.The
  limited gammut of sRGB clips cyans, blues and
  greens quite significantly

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WYSIWYG

• Now my monitor is FAITHFUL but my prints still
  dont match!!!
• Why???
• Every paper and ink combination reacts
  differently.

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WYSIWYG

• A printer profile tells the computer how a
  certain printer, with certain inks and certain
  paper is going to print out your image.
• A different profile is needed for each different
  type of paper and ink even if the printer is the
  same.

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Ways To Help Ensure WYSIWYG

• Use manufacturers inks and papers -make sure you
  use the appropriate settings. Canned Profile
• Experiment
• Download Profiles
• Make your own
• Use a professional bureau

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AUSMEDIA.COM.AU

• Russell Martyn
• 442 Station St, Box Hill
• 1800 00 88 99

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SilverFast Drivers by LaserSoft

• IT8 Calibration Target
• More Control
• Better Descreening
• Improve Dynamic Range
• Enable Multipass Scanning
• Film Profiles
• 150 - 1000
• www.silverfast.com