Industry Regulations & Standards

CCITT two-dimensional

Understanding CCITT Two-Dimensional Coding: A Deep Dive into Modified Relative Element Address Designation

The CCITT (International Telegraph and Telephone Consultative Committee) two-dimensional coding scheme, also known as Modified Relative Element Address Designation (MREAD), offers an efficient way to represent changes in a two-dimensional image or data structure. This approach is particularly useful in situations where the changes between lines are relatively small and localized.

How It Works:

MREAD utilizes a reference line, typically located directly above the current line, to encode the position of changing elements. The code for each changing element on the current line is determined by its relative position to:

  1. The changing element on the reference line: This applies if the changing element on the current line has a counterpart on the reference line. The code represents the horizontal distance between the two elements.
  2. The preceding changing element on the current line: This is used if the changing element doesn't have a direct counterpart on the reference line. The code indicates the horizontal distance from the previous changing element on the current line.

Advantages of CCITT Two-Dimensional Coding:

  • Efficient Representation: MREAD significantly reduces the amount of data needed to represent an image, particularly when the image contains areas of low complexity or gradual changes.
  • Simplicity and Ease of Implementation: The coding logic is straightforward and can be easily implemented in hardware or software.
  • Minimal Overhead: The reference line only needs to be stored once, and the codes for changing elements are relatively compact.

Example:

Imagine a simple black and white image where the reference line (above) is represented by the sequence "010010" and the current line is "011010". The changing elements on the current line are at positions 2 and 3, which correspond to the changing elements on the reference line.

Using MREAD, the code for the changing element at position 2 would be "0" (as it's the same position as on the reference line). The code for the changing element at position 3 would be "1" (as it is one position to the right of the corresponding element on the reference line).

Applications of CCITT Two-Dimensional Coding:

MREAD finds its application in various fields, including:

  • Image Compression: It's used in fax machines and other image compression techniques to efficiently transmit images.
  • Data Transmission: The scheme helps reduce the data volume required for transmitting line drawings and other graphic data.
  • Document Scanning: It plays a role in scanning documents, where differences between consecutive lines are often minimal.

Conclusion:

CCITT two-dimensional coding, with its MREAD approach, is a valuable tool for representing data efficiently. By exploiting the correlation between consecutive lines, it minimizes the amount of data needed to transmit or store images and other information. This makes it a valuable technique in various applications requiring efficient data handling and transmission.


Test Your Knowledge

CCITT Two-Dimensional Coding Quiz

Instructions: Choose the best answer for each question.

1. What is the primary advantage of using CCITT two-dimensional coding with Modified Relative Element Address Designation (MREAD)?

a) It efficiently encodes images with complex patterns. b) It significantly reduces data required for representing images with localized changes. c) It allows for lossless compression of images with high detail. d) It offers enhanced security for transmitting image data.

Answer

b) It significantly reduces data required for representing images with localized changes.

2. What is the reference line in CCITT two-dimensional coding used for?

a) To provide a baseline for color values in the image. b) To indicate the starting point for encoding data. c) To define the boundaries of the image. d) To establish a reference for identifying changes in the current line.

Answer

d) To establish a reference for identifying changes in the current line.

3. How is the code for a changing element determined in MREAD?

a) By its absolute position within the image. b) By its color value. c) By its relative position to the changing element on the reference line or the preceding changing element on the current line. d) By its distance from the edge of the image.

Answer

c) By its relative position to the changing element on the reference line or the preceding changing element on the current line.

4. Which of the following applications is NOT a common use case for CCITT two-dimensional coding?

a) Image compression in fax machines. b) Video streaming services. c) Document scanning. d) Data transmission of line drawings.

Answer

b) Video streaming services.

5. What is a key characteristic of CCITT two-dimensional coding that makes it suitable for efficient data handling?

a) It relies on complex algorithms for data compression. b) It requires significant processing power to encode and decode images. c) It utilizes a simple and straightforward coding logic. d) It is highly adaptable to various image formats and resolutions.

Answer

c) It utilizes a simple and straightforward coding logic.

CCITT Two-Dimensional Coding Exercise

Instructions:

You are tasked with encoding the following two lines of a black and white image using CCITT two-dimensional coding with MREAD:

Reference Line: 01001010

Current Line: 01100010

Task:

  1. Identify the changing elements on the current line compared to the reference line.
  2. Determine the codes for each changing element based on the MREAD rules.
  3. Write down the encoded representation of the current line, including the codes for the changing elements.

Exercice Correction

1. Changing Elements: The changing elements on the current line are at positions 2 and 3. 2. Codes: * Position 2: Code is "0" (same position as the changing element on the reference line). * Position 3: Code is "1" (one position to the left of the corresponding element on the reference line). 3. Encoded Representation: The encoded representation of the current line would be: 01000110 This representation includes the original elements of the current line with the codes for the changing elements inserted at their respective positions.


Books

  • "Digital Image Processing" by Rafael C. Gonzalez and Richard E. Woods: This classic textbook covers image compression techniques, including MREAD, in detail.
  • "Image Compression Techniques" by Khalid Sayood: This comprehensive book explores various image compression methods, including CCITT group 3 and 4 standards that utilize MREAD.
  • "Data Compression: The Complete Reference" by David Salomon: This reference book discusses run-length coding and other compression techniques, some of which are related to MREAD.

Articles

  • "A Study of the CCITT Two-Dimensional Coding Scheme for Facsimile Transmission" by S. Morishima, et al.: This article provides a technical analysis of the MREAD algorithm used in fax machines.
  • "Modified Relative Element Address Designation (MREAD) for Efficient Image Compression" by R. Sharma, et al.: This paper discusses the implementation and optimization of MREAD for image compression.
  • "Run Length Coding for Image Compression: An Overview" by M. Khan, et al.: This paper explores run-length coding techniques, which are closely related to the principles of MREAD.

Online Resources

  • ITU-T (International Telecommunication Union): The ITU-T website provides access to various standards and recommendations, including the CCITT group 3 and 4 standards for facsimile transmission.
  • *Wikipedia: * https://en.wikipedia.org/wiki/ModifiedRelativeElementAddressDesignation Provides a basic overview of MREAD and its usage.
  • Online technical forums: Websites like Stack Overflow and Reddit can provide valuable discussions and insights on MREAD implementations.

Search Tips

  • Combine search terms: Use combinations like "CCITT two-dimensional coding," "Modified Relative Element Address Designation," and "MREAD."
  • Specify publication types: Add terms like "pdf," "journal article," or "book" to your search query to filter results.
  • Focus on specific applications: Include keywords like "fax transmission," "image compression," or "document scanning" to narrow down the search.
  • Explore related concepts: Use keywords like "run-length coding," "image coding," and "facsimile standards" to discover additional resources.

Techniques

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