Final Exam Prep Flashcards
Prep for final exam (38 cards)
How do you control your printer to get accurate colour? (3 methods)
1) Manually adjusting images based on printer response (inaccurate)
2) Software based RIP to manage ICC conversions (professional preferred)
3) Turn off all colour management in printer and have applications manage colour using ICC profiles (best budget way
Describe the process of printer calibration (in-class)
1) Print out chart
2) Measure chart with device
Describe the process of monitor calibration (in-class)
1) Flashing colours are measured by device and profile meas
What is metamerism? How is this useful in colour management?
When two colours with different spectral values appear the same in one lighting condition, but may appear different as the lighting conditions change.
We use it in colour management to create a visually pleasing match bewteen what we see on a monitor (RGB) and what we see in print, essentially two different lighting and colour spaces
What is the CIE?
Centre Intenationale d’Eclairage
Who created the first 3D colour spaces in 1928 - 1932, and what was that colour space?
John guild + David Wright, XYZ colour space
Why is the LAB colour space so important/what are 3 characteristics of LAB?
It is device independent, mathematically created and consistent
What is a colour gamut?
The limit or range of colour a specific device can produce
What colour is 255 Red + 255 Green + 255 Blue?
White
List 2 examples of Gamut Reduction
1) Conversion from RGB to CMYK
2) Printing on uncoated vs coated paper
What does CMM stand for? What does it do?
Colour Management Module
The CMM uses a mathematical formula to convert an input ICC Profil to it’s output ICC profile. The CMM will convert the input profile to LAB colour descriptions, and converts those into the most pleasing replica of those colours in the output ICC Profile (depending on rendering intent)
What are the 4 main components of Colour Management? What do they do?
1) ICC Profiles - creates a standardized colour code specific to the device
2) CMM - mathematical formula used to translate LAB colour to destination ICC profile
3) PCS - central hub of decoding the ICC codes into a description of colour like LAB
4) Rendering Intents - User choice of HOW input ICC should be converted to output ICC
What are the 4 C’s of Colour Management?
Consistency, Calibration, Characterization, Conversion
What does PCS stand for? What is the PCS?
Profile Connection Space
This is the central hub of the workflow between the source ICC profile and the destination ICC profile (where the math lives)
How many colours are possible in an 8 bits per channel colour monitor?
16.7 million
What are rendering intents?
Your input into how you want to convert colour from one gamut to another.
What are the 4 rendering intents and what are their characteristics?
1) Perceptual - slightly changes ALL colours, preserves relationship between source colours
2) Relative Colormetrics - only modifies out of gamut colours to nearest colour in destination space, white point mapped to destination white point
3) Absolute Colour Metrics - converts to absolute LAB coordinates and does not adjust for whitepoint difference, better for CMYK to CMYK
4) Saturation - tries to produce vivid colours at expense of colour accuracy
What is the difference between assigning and converting a profile (in Photoshop)?
Assign = colour shift into a different gamut - colours directly mapped to new colour space
Convert = use rendering intents to convert colour and maintains the integrity of the colour
What is the “colour event”?
When light strikes an object and reflects, and is seen by the human eye
What is Delta E?
The mathematical distance between 2 colours in a 3 dimensional colour space
What are the 3 printing methods in North America?
SNAP (Newsprint)
GRACol (High-quality gloss)
SWOP (Magazine gloss, usually default b/c can print on newspaper and be ok)
What is GCR? Describe
Gray Component Replacement
Removes the CMY from shadows and replacing the colour with black. Main function is to control total amount of ink volume, and makes project more stable and less prone to metamerism
What 4 elements are measured when calibrating a monitor?
Phosphers (LED or LCD)
Gamma (like gamut)
Brightness/Contrast
Whitepoint (in Kelvins)
What is a:
1) Densitometer
2) Colorimeter
3) Spectrophometer
1) measures DENSITY of film or volume of ink/pigments - colourblind, used for dot gain
2) Optical measurement instrument that responds to colour, performs CIE calculation - monitor calibration
3) measures spectral data as well as density data, can do the work of both 1 + 2
