Questions and Answers
What is the process of translating an image into digital code for storage called?
Digitalization
Which of the following are sources of digital images? (Select all that apply)
What does a pixel represent in a digital image?
A small dot that creates the image on a computer screen
A binary image has pixel values of ______
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A grayscale image has pixel values ranging from ______
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What does RGB stand for in color images?
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How many pixels are in an image that measures 2048 x 1536?
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Which of the following is NOT a common image file type?
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If an image is 500 x 500 pixels, how many bytes are needed to store a color image?
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What is the term for the resolution of an image?
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Calculate the total resolution of an image that is 400 x 600 pixels.
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Study Notes
Computer images are stored in various formats and resolutions as digital code. Sources include digital cameras, scanned media, digital TV signals, computer graphics, and the Internet. A pixel is a small dot on a screen, where patterns of pixels create color, with one pixel representing one byte of data.
- Most common pixel format is the byte image, storing numbers as 8-bit integers with values from 0 (black) to 255 (white).
- Images can be in different pixel value formats:
- Binary Images: values are 0 or 1
- Grayscale Images: values range from 0 to 255
- Color Images: each pixel has three components (Red, Green, Blue) with values from 0 to 255
Image Digitization Process
- Images undergo a two-step digitization:
- Sampling: capturing the continuous image
- Quantizing: converting sampled pixels into digital values
Image Resolution
- Resolution indicates the number of pixels within an image, often described by width x height.
- Example: An image with dimensions 2048 x 1536 has over 3.1 Megapixels, equating to 3,145,728 pixels.
Storing Digital Images
- Digital images are saved as files, requiring specific formats for the organization of bytes.
- File types, which dictate storage compatibility, include:
- GIF (Graphic Interchange Format)
- JPEG (Joint Photographic Experts Group)
- PNG (Portable Network Graphics)
- BMP (Bitmap)
Size of Stored Images
- Example calculation for a 500 x 500 pixel image:
- Total Resolution: 250,000 pixels
- Binary Image Storage: 31,250 bytes (1 bit/pixel)
- Grayscale Image Storage: 250,000 bytes (8 bits/pixel)
- Color Image Storage: 750,000 bytes (24 bits/pixel)
Example Task Calculations
- For a 400 x 600 pixel image, determine:
- Total resolution
- Storage requirements for binary, grayscale, and color images
Magnetic Disk Storage Overview
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A magnetic disk with 12 platters contains:
- 5,000 tracks per surface
- 20 sectors per track
- Each sector holds 3KB of data
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Tasks involve calculating:
- Capacity of a track
- Capacity of a surface
- Total HDD capacity
- Capacity of a cylinder
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Description
This quiz focuses on Lecture #11 of CS101.3, which covers the fundamentals of computer storage structures, specifically optical disks and image representation. Explore how computer-generated images are stored and the digital formats used for various types of files.
