basic introduction to graphic file formats
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Graphic File Formats
Basic Introduction
10/4/2015 1Ankit Mishra|CS1Fb.com/djankit007
Topics To Be Covered
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Introduction
Multimedia File Formats
Graphic File Formats
Bitmap Image
Vector Image
Comparision
Conclusion
Introduction
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Multimedia data and information are
stored in a file using certain formats
specific to the type of multimedia
content.
File
•Digital storage of data.
Format
•The way content (data) is
stored.
Multimedia File Formats
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A typical multimedia file may contain a specific or
a wide range of data such as
graphic,video,animation,MIDI information,fonts
etc.
MULTIMEDIA FORMATS
Video
AnimationGraphic
Audio
Graphic File Formats
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Graphic file formats are standardized means
of organizing and storing digital images.
.bmp
.gif
.jpeg
.png
Bitmap
.svg
.cgm
.eps
Vector
Image Resolution
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Resolution refers to the total number of pixels in an image.
For example: An image that is 1920*1080 (1920 pixels
wide and 1080 pixels high contains 1920*1080 =
2073600 pixels (or 2.1 Megapixels).
Bitmap Image
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Bitmap (or raster) images are stored as a series/grid of tiny dots called pixels.
Pixels are blocks representing smallest unit of information arranged in a
2-D grid. Bit depth of a pixel represents the relative amount of colour
information present in it.
Bitmap Image Format
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The density of the dots, known as the resolution,
determines how sharply the image is represented. In
typical bitmaps, image pixels are generally stored with
a color depth of 1, 4, 8, 16, 24, 32, 48, or 64 bits per
pixel.
Bitmap images are resolution dependant. On resizing a
bitmap image, quality gets sacrificed.
Representing Images In Bitmap
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Images need to be converted into binary in order for a computer to
process them so that they can be seen on our screen.
Digital images are made up of pixels where each pixel in an image is
made up of binary numbers. For example: 1 bit per pixel (0 or 1) gives
two possible colors to represent an image.
If 1 is black
and 0 is
white then
a simple
B&W
picture can
be created
using binary.
Representing Images In Bitmap
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We can get more possible colors by using more bits per pixel.
1 bit per pixel (0 or 1): 2 possible colours
2 bits per pixel (00 - 11): 4 possible colours
3 bits per pixel (000 - 111): 8 possible colours
4 bits per pixel (0000 - 1111): 16 possible colours
8 bits per pixel : 256 possible colours 16 bits per pixel : 65k possible colours
24 bits per pixel : 16 Million possible colours
32 bits per pixel : 4 Billion possible colours
Size of an image = (Rows) X (Columns) X (Bits per pixel(bpp))
Representing Images In Bitmap
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RGB color scheme is a method of mixing (R)ed, (G)reen and (B)lue light
in order to produce almost any imaginable color.
Here, a pixel stores 8
bits of information
(color) for each
Red(R),Green(G) &
Blue(B) which has
integer values from
0 to 255. This makes
256*256*256=16
million possible
colors.
RGB Color code: (127,127,203)
Representing Grayscale Image
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Grayscale image has number of shades of gray per pixel.
Where shades of gray are the levels of color between Black (0)
and White(1).
An 8 bit grayscale image contains 2^8=256 levels.
This 8 bit grayscale image has 1024
rows and 1024 columns hence,
Size = 1024 * 1024 * 8 = 8388608 bits
or 1 Mb.
Common Bitmap Image Formats
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Scanned images and images taken from digital camera are
all bitmap.
.gifGraphics
Interchange Format
Web graphics, buttons, chart,
icons.
.jpgJoint
Photographic Expert Group
Web images
.tiff
Tagged Image File Format
High Quality Photographs
Vector Image Format
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Unlike bitmap, vector graphics are not made up of a grid of pixels. Instead, vector graphics are made up of mathematical equations,
series of draw instruction comprised of paths, which are defined by a start and end point, angles, lines, squares, triangles, or curve shapes
etc. These shapes are called objects and each object has some attributes (colour,fill,outline,shadow etc)
Vector graphics are resolution independant. Resizing a
vector image won’t effect its sharpness or crispness.
Vector Image Format
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Vector graphic also includes metafiles, which are graphics
that contains both bitmap (raster) and vector data. Objects
are bitmap but attributes are vector.
Some common vector metafile formats are: .CGM (Computer Graphic Metafile), .EMF (Enhanced Metafile Format), .WML (Windows Metafile)
Common Vector Image Formats
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Vector images can be zoomed or scaled at any ratio thus, can be used for designing logos or magazines. They can’t be used for generating photo-realistic
imagery.
.cdr
CorelDRAWvector graphics
Vector illustrations, page layout, brouchures
.swf
ShockWave Flash
web-based video games
.ai
Adobe Illustrator
Layers, vectors, effects etc
Conclusion
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• The choice to use bitmap or vector depends on the
design itself.
• If it's going to have photographic elements with
continuous tones and blends of color, one should use
bitmap editing programs like Photoshop.
• And if considering final design to look like an illustration
with clear contrasts between objects & shapes, then use
a vector program like adobe illustrator.
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