Digital Image Acquisition and Representation
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Questions and Answers

What is the formula for calculating dynamic range in terms of light?

  • Largest amount of light - Smallest amount of light (correct)
  • Smallest amount of light - Largest amount of light
  • Largest amount of light + Smallest amount of light
  • Largest amount of light / Smallest amount of light

    • Which dynamic range corresponds to normal imagery?

  • 0 - 4095
  • 0 - 255 (correct)
  • 0 - 65535
  • 0 - 16383

    • What issue arises from the incorrect use of dynamic range?

  • Saturated or under-exposed images (correct)
  • Color distortion
  • Blurred images
  • Pixelation

    • At what bit depth does 'false contouring' typically become apparent?

    <p>4 bpp and below</p> Signup and view all the answers

    For typical display purposes, what is the standard bit depth used per pixel?

    <p>8 bpp</p> Signup and view all the answers

    What is the primary difference between grayscale and color images?

    <p>Grayscale images are composed of brightness values, while color images consist of multiple channels representing primary colors.</p> Signup and view all the answers

    How many values typically represent a color in a color space?

    <p>3 or 4 values</p> Signup and view all the answers

    Which color space is recognized as the most common?

    <p>RGB</p> Signup and view all the answers

    What advantage does the HSV color space offer?

    <p>It maintains invariance to illumination changes.</p> Signup and view all the answers

    What does an image histogram represent?

    <p>The distribution of image pixels based on their grayscale levels.</p> Signup and view all the answers

    What is the primary role of a charge-coupled device (CCD) sensor in digital image acquisition?

    <p>To measure brightness and color</p> Signup and view all the answers

    Which operation is NOT a part of data preprocessing in image processing?

    <p>Background subtraction</p> Signup and view all the answers

    The spatial resolution of an image primarily determines which aspect of image quality?

    <p>The level of detail present in the image</p> Signup and view all the answers

    In the context of image segmentation, which technique is primarily used for identifying moving objects in video?

    <p>Kalman Filter</p> Signup and view all the answers

    What does the variable 'I(x,y)' represent in digital image representation?

    <p>The brightness at position (x,y)</p> Signup and view all the answers

    Which of the following best describes the relationship between continuous images and discrete images?

    <p>Discrete images are samples of continuous images</p> Signup and view all the answers

    What characterizes the process of 'Brightness enhancement' in image processing?

    <p>Modifying the intensity values to improve visibility</p> Signup and view all the answers

    Which of these is NOT a feature of image characteristics?

    <p>Data compression ratio</p> Signup and view all the answers

    What is the primary purpose of compression in video recordings?

    <p>To reduce the amount of information to be transmitted or stored</p> Signup and view all the answers

    Which of the following describes lossless compression?

    <p>It allows for perfect reconstruction of the original data</p> Signup and view all the answers

    What is meant by 'temporal redundancy' in video compression?

    <p>Exploiting similarities between consecutive frames</p> Signup and view all the answers

    Which of the following codecs is considered a lossy compression method?

    <p>JPEG</p> Signup and view all the answers

    In which scenario are keyframes used in video compression?

    <p>During moments of major scene change or sudden movement</p> Signup and view all the answers

    What is the characteristic of images processed with lossless compression?

    <p>There is no loss of quality from the original image</p> Signup and view all the answers

    How does the cumulative histogram function H(J) differ from the standard histogram?

    <p>It shows the cumulative number of pixels with values less than or equal to J</p> Signup and view all the answers

    Which of the following refers to standard file formats that can use various codecs for video playback?

    <p>AVI</p> Signup and view all the answers

    Study Notes

    Digital Image Acquisition

    • The ubiquitous video camera is the source of imagery
    • The Charge-coupled device (CCD) sensor is used to acquire images
    • It measures brightness or intensity and color
    • 3CCD is used for color images
    • The CCD sensor has a rectangular array of detectors

    Digital Image Representation

    • Optical images can be expressed as I(x,y) where I(x,y) represents brightness at position (x,y)
    • X and Y are spatial coordinates
    • This can be digitally represented as a two-dimensional array

    Image Characteristics

    • Spatial resolution: A measure of image quality in terms of detail, determined by the CCD sensor
    • Dynamic range: Measure of the range of brightness values a sensor can detect, usually expressed in bits (8 bits = 256 shades of gray)
    • Gray-level quantization: Measure of the accuracy of the digitization process, represents how many levels of gray are used for a given dynamic range
    • Color Space: Mathematical model that represents colors as a vector of numbers, providing features like invariance to color variation, shadows, reflections, and illumination changes. Common color spaces include RGB and HSV.

    Image Histograms

    • It visually shows the distribution of image pixels in terms of their gray levels
    • It is a plot of Ni versus i, where Ni is the number of pixels with gray level i
    • Cumulative Histogram: Shows the number of pixels with a specific value (number of pixels with value == J)

    Image Compression

    • Goal: Reduce the amount of information transmitted or stored by taking advantage of redundancy in images and videos
    • Types of Compression: Lossless compression (perfectly reconstructs original data) and Lossy compression (approximates the original data)
    • Common compression techniques: M-Jpeg, Mpeg, H.264, DIVX, WMV, Sorenson, 3GP.
    • File formats (containers) like AVI and MOV can use these codecs.
    • Common image compression techniques: JPEG, GIF, PNG

    Video Processing

    • Slow motion effect in video is achieved by increasing the frame rate.
    • Compression techniques can be used to reduce the size of video files
    • Temporal Redundancy is a significant source of information that can be used for compression
    • Keyframes are frames without temporal compression (for example, change of scene)
    • Framerates used in surveillance applications are typically low (1-2 frames per second) to save storage space and bandwidth.

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    Related Documents

    2-ImageCharacteristics+-+Students copy.pptx

    Description

    Explore the fundamentals of digital image acquisition and representation in this quiz. Understand how CCD sensors work, image characteristics such as spatial resolution and dynamic range, and the representation of optical images as two-dimensional arrays. Test your knowledge of color spaces and gray-level quantization.

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