Download - 1 Pixels & Images
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• An image is a 2D array of pixels.
• An image is an array, or a matrix, of square
pixels (picture elements) arranged in columns
and rows.
What Is An Image?
and rows.
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Pixel?
• A pixel is the smallest visual element on a
video display screen.
• PIX (for picture) + “EL" (for element).
Pixel's Of Image.
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More On Pixels
• This example shows an image with a portion
greatly enlarged, in which the individual pixels
are rendered as little squares and can easily
be seen.be seen.
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How is a pixel stored?
• Pixels are stored as Integers.
• The integers can be 8-bit, 24-bit or 32-bit
depending on the image type.
• Most popular are 24 bit color images where 8 • Most popular are 24 bit color images where 8
bits each for Red, Green And Blue color values
are used to represent a 24-bit pixel value.
• 8 bit images are grayscale images where as 32
bit images have an additional transparency
channel.
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RGB Color Model
• The RGB color model is an additive color
model in which red, green, and blue color is
added together in various ways to reproduce a
broad array of colors.broad array of colors.
• In computing, the component values are often
stored as integer numbers in the range 0 to
255. These may be represented as either
decimal or hexadecimal numbers.
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RGB Color Images
• Color images are composed
of three different channels
viz. Red, Green and Blue.
• One can also imagine three • One can also imagine three
overlapped 8-bit images to
compose a final 24-bit color
image.
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RGB Color Example
• Sample PIXEL value in HEX = 0EDEB5
• In programming the hex numbers are
represented as 0x0EDEB5. 0x prefix is for hex
notation.notation.
• Then individual color channels:
• 0E (red) - DE (green)- B5 (blue)
• 00001110 – 11011110 – 10110101
• Actual Color Composed Will Be :
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A Little Experiment
• Using Microsoft Paint try creating new color
compositions. See how individual values of R,
G and B can be used to form different colors.
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Grayscale Image
• In a (8-bit) grayscale image each picture
element has an assigned intensity that ranges
from 0 to 255.
• A grey scale image is different from black and • A grey scale image is different from black and
white image since a grayscale image also
includes shades of grey apart from pure black
and pure white color.
• Grayscale images are usually required for
image processing.
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Different Image Types
• COLOR – GRAYSCALE - BLACK & WHITE