The document discusses input devices in computer graphics, focusing on light pens and voice command systems. It describes a light pen's functionality, advantages, and limitations, while also covering voice commands and speech recognition technologies used for operating devices hands-free. Additionally, the document notes common faults associated with each input device.

1. Computer Graphics
Topic : Input DevicesInput Devices
Light Pen
Voice System
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3. Definition
An input device that uses a light-sensitive
detector to select objects on a display screen.
Wired to a video terminal used to draw
pictures or select menu options.
It allows the user to point to displayed objects,
or draw on the screen.
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4. Uses
Can be used on a computer screen, TV
screen and a smart board.
A light pen is similar to a mouse.
Construction
It includes a light that is detected by the pixels
on the screen.
It has a photoreceptor for sensing the signal.
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5. Fault
Short lifespan.
Being easily damaged.
Works only with any CRT-based display , but
not with LCD screens.
When pointed at the screen, part of the
screen image will be covered by the hand and
pen.
Too much light can confuse the sensor, cause
it to operate differently. 5

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7. Application
Voice Command
Speech Recognizer
Dragon
Podcast
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8. VOICE COMMAND
It is a device controlled by means of the human voice.
By removing the need of using buttons, dials and
switches, users can easily operate appliances while doing
other tasks . Speech recognition converts spoken words
to text.
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9. Speech Recognizer
It is commonly used in Graphic Workstations.
Commands are given through Microphones mounted on
Headsets.
When a voice command is given, the system searches
the dictionary for a match.
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10. Fault
• The speaker must have great voice clarity.
• Words may changed.
• Requires paid software.
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11. Questions…
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12. By,
Akshay Kumar M S
BCA’14
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