Podcast
Questions and Answers
What happens to the iso-preference curves as the values for N and k increase?
What happens to the iso-preference curves as the values for N and k increase?
- The curves remain constant.
- The curves become horizontal.
- The curves shift right and upward. (correct)
- The curves shift left and downward.
Which interpolation technique creates a chessboard effect due to pixel replication?
Which interpolation technique creates a chessboard effect due to pixel replication?
- Bilinear interpolation
- Cubic interpolation
- Nearest neighbor interpolation (correct)
- Higher-order non-linear interpolation
How can an image be reduced in size when it is too large to fit on the screen?
How can an image be reduced in size when it is too large to fit on the screen?
- By zooming in on the image.
- By generating a half-sized version. (correct)
- By increasing the pixel resolution.
- By applying bilinear interpolation only.
What does a vertical shift in the iso-preference curves suggest about images with high detail?
What does a vertical shift in the iso-preference curves suggest about images with high detail?
Which of the following interpolation methods utilizes four nearest neighbors to determine new pixel values?
Which of the following interpolation methods utilizes four nearest neighbors to determine new pixel values?
What does a high dynamic range image represent?
What does a high dynamic range image represent?
If an image is represented by $N = 2048$ and $k = 8$, how many bytes does it occupy?
If an image is represented by $N = 2048$ and $k = 8$, how many bytes does it occupy?
How is a binary image defined?
How is a binary image defined?
What is the total number of colors that can be represented in the RGB color model?
What is the total number of colors that can be represented in the RGB color model?
Which of the following statements about spatial resolution is true?
Which of the following statements about spatial resolution is true?
What does gray-level resolution indicate?
What does gray-level resolution indicate?
How many gray levels are available in a gray-level image represented by 1 byte?
How many gray levels are available in a gray-level image represented by 1 byte?
What is the relationship between spatial resolution and image size?
What is the relationship between spatial resolution and image size?
What are the two primary stages in the digitization process of images?
What are the two primary stages in the digitization process of images?
In the equation $L = 2^k$, what does 'L' represent?
In the equation $L = 2^k$, what does 'L' represent?
What does the dynamic range of an image refer to?
What does the dynamic range of an image refer to?
What does the spatial resolution of an image refer to?
What does the spatial resolution of an image refer to?
Which representation method is NOT commonly used for digital images?
Which representation method is NOT commonly used for digital images?
If an image has 8 bits for gray-level quantization, what is the gray-level resolution?
If an image has 8 bits for gray-level quantization, what is the gray-level resolution?
What happens during the image sampling process?
What happens during the image sampling process?
Which of the following is true about quantization in image processing?
Which of the following is true about quantization in image processing?
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Study Notes
High Dynamic Range
- High dynamic range (HDR) refers to a higher contrast image, meaning the difference between the darkest and lightest areas of the image is greater.
Image Storage Requirements
- The number of bits required to store an image is calculated using the formula: b (bit)= 𝑀 × 𝑁 × 𝑘 or b (bit)= 𝑁 2 × 𝑘
- 𝑀 represents the number of rows, 𝑁 represents the number of columns, and 𝑘 represents the number of bits per pixel.
- Example image sizes:
- 𝑁=256, 𝑘=8: 65536 bytes
- 𝑁=2048, 𝑘=8: 12 M bytes
- 𝑁=8192, 𝑘=8: 192 M bytes
Image Representation
-
Binary Image:
- Represents pixels with only two values (0 or 1) using 1 bit.
- A 256×256 binary image file is 65,536 bits or 8,192 bytes.
-
Grey-Level Image:
- Represents pixel values using 1 byte (28), ranging from 0 to 255, representing black to white with 256 grey levels.
- A 256×256 grey-level image file is 65,536 bytes.
-
Color Images:
- RGB Model: Utilizes Red, Green, and Blue primaries to represent color.
- Number of Representable Colors: (28)3 = 224 = 16,777,216 (true color)
- Examples:
- (0, 255, 0): Green
- (255, 0, 0): Red
- (0, 120, 0): Light Green
- (100, 100, 0): Yellow
Spatial and Intensity Resolution
- Spatial Resolution: The smallest discernible detail in an image, measured as dots (pixels) per unit distance.
- Related to image size but not the same.
- Grey-Level Resolution: The smallest discernible change in intensity level.
- Measured in the number of grey levels used (e.g., 256 levels, 128 levels, etc.)
Empirical Study of Resolutions
- Goal: To determine the impact of 𝑘 (bits per pixel) and 𝑁 (image size) on image quality.
- Iso-Preference Curves:
- Larger values of 𝑁 and 𝑘 generally lead to better picture quality.
- Curves tend to become vertical as the detail in the image increases, indicating that for high-detail images fewer intensity levels are required.
Zooming and Shrinking Digital Images
- Zooming: Increasing the size of an image.
- Methods:
- Nearest Neighbor Interpolation: Replicating pixels, resulting in a chessboard effect.
- Bilinear Interpolation: Using four nearest neighbors for interpolation.
- Higher-Order Non-linear Interpolation: Using more neighbors for interpolation.
- Methods:
- Shrinking: Reducing the size of an image.
- Used to resize large images for display on smaller screens.
Image Sampling and Quantization
- Digitization Process: Converts continuous data 𝑓(𝑥, 𝑦) into a digital image.
- Sampling: Digitizing coordinate values (determining 𝑀 and 𝑁).
- Quantization: Digitizing amplitude values (determining gray-level resolution 𝐿, where 𝐿 = 2𝑘).
- Dynamic Range: The range of values spanned by the gray scale, from 𝐿𝑚𝑖𝑛 to 𝐿𝑚𝑎𝑥.
Representing Digital Images
- Digital images can be represented in three ways:
- A 2.5D Plot: Visualizes the function as a topography.
- An Image on a Monitor: Allows for visual representation of the image.
- Printing Numerical Values in an Array: Useful for implementation in algorithms.
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