which is the pink pen? here is the pink pen (example taken from )
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Which is the Pink Pen?
Here is the Pink Pen
(Example taken from http://www.colourblindawareness.org)
Light and Colour
The Solar Cell
Converts light into electricityThe stronger the light the more electricity
Measure the Current to Measure the Light Levels
Voltage
Light
Analogue to Digital Conversion
To store three volts we need 2 bits00 = 001 = 110 = 211 = 3
0 3
Light
Analogue v Digital Data
How to represent 10 hours and 15.34567890 minutes?
Quantisation Error
White 15% Grey 30% Grey0 0.3 0.4
White White White0 0 0
Our analogue source gives us
The digital representation becomes
When Applied to an Image
Create an Array of Digital Detectors
Project the Image onto the Array
Using 1 bit per Pixel
Increase the Image Resolution
Increase the Colour Resolution
Colour Resolution and Image ResolutionColour Resolution relates to the depth of
colour the image reproduces. The more bits we use to represent a single pixel the greater the number of colours may be stored in that pixelColour resolution is not related to the size of the
imageWe could have a 1 x 1 pixel image and still have a
colour resolution of 16 million colours – 24 bit colour! (Not that there would be a lot of point.)
Image resolution relates to how many pixels make
up the height and width of the image per inch – dots per inch. Image resolution is an issue when it comes to the
size of the image in dpi
Low Image Resolution Images Don’t Re-Size Well
Both images have high colour resolution
Colour Representation - RGB
Combine Red Green and BlueAlso referred to as 24 bit colourVery common in computing
Black rgb(0,0,0)Red rgb(255,0,0)Green rgb(0,255,0)Blue rgb(0,0,255)Yellow rgb(255,255,0)Cyan rgb(0,255,255)Magenta rgb(255,0,255)Grey rgb(192,192,192)White rgb(255,255,255)
CMYK (Cyan, Magenta, Yellow & Black)
Subtract RGB by mixing Cyan Magenta Yellow and BlackCommon in printing industry and computer printers
The Scanner
InterpolationHow can a 600dpi scanner scan at 1200 dpi?
Without Interpolation With Interpolation
Digital to Analogue ConversionThe Display Adapter / Monitor – Device Resolution
In the case of a monitor, the quality of the equipment is called the dot pitch.
The dot pitch is the distance in millimetres of dots of the same colour.
In the case of a typical monitor the dot pitch is .28, meaning there is .28 mm between the red dots (green dots or blue dots).
The smaller the dot pitch, the higher the quality of the equipment.
The Output from the Graphics CardImagine we scanned in an A4 document at a
resolution of 600 dpi.Displayed on a monitor with a 72dpi graphics
adaptor
Very Common in Student Work
More important when we design for mobile devicesDesign for liquid layout
Displays with Lower Colour ResolutionQ. “How do I view a 16 million colour image
256 colour display?”A. Dithering
A is the original unchanged image B is 1 bit monochrome with dithering C is 1 bit monochrome without dithering
– note the loss of detail D is 8 bit colour with dithering
– note the speckled effect which is common to this process
Gamma CorrectionImages do not display the same across
different hardware platforms
Becomes
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