Hash Value Based Duplicate Detection in Image Forming Systems
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Solution Overview
Problem
Conventional image forming systems face challenges in accurately and efficiently determining whether print data is redundant, leading to inconvenient delays and inaccurate determination of duplicate files, especially when comparing character and image data.
Innovation Solution
An image forming system that uses hash values to determine if a file has already been printed, where a terminal generates a hash value of the file and compares it with stored hash values, only transmitting print data if the hash value is not found in the storage unit, thereby avoiding duplicate printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If whole image data are compared to determine duplicate files, then determination accuracy is improved, but determination time increases significantly
Solution Approach 1:
The patent extracts a hash value (a condensed representation) from the entire image data and uses this extracted feature for comparison instead of comparing the complete large-volume image data. This extraction principle reduces the comparison workload from megabytes of image data to a small hash value, dramatically reducing determination time while maintaining accuracy through the use of collision-resistant hash functions.
Solution Approach 2:
The patent transforms the comparison parameter from raw image data (pixels, colors, shapes) to a hash value parameter. This parameter change converts a complex multi-dimensional comparison problem into a simple string comparison, achieving both speed and accuracy. The hash function serves as a parameter transformation that preserves the uniqueness property needed for accurate duplicate detection.
2Loss of time
If only character data or only image data are compared to determine duplicates, then determination time is reduced, but determination accuracy deteriorates
Solution Approach 1:
The patent applies a universal hash function that can process any type of data (character data, image data, mixed content) through the same mechanism. Instead of having separate comparison methods for different data types, the hash function serves as a multi-functional tool that converts any data type into a comparable format, reducing determination time while maintaining accuracy across all data types.
3Ease of operation
If print data is stored in the storage device for future printing, then user convenience is improved, but storage redundancy increases
Solution Approach 1:
The patent performs preliminary duplicate detection by comparing the hash value of incoming print data against stored hash values before actual printing occurs. This preliminary action prevents redundant storage of duplicate files while maintaining the capability to quickly retrieve and print previously stored files, thus reducing storage redundancy without compromising user convenience.
Solution Approach 2:
The patent introduces hash values as an intermediary layer between the print data and the storage device. Instead of directly storing and comparing all print data, the system stores compact hash values as intermediaries that represent the uniqueness of files. This intermediary mechanism enables efficient duplicate detection and reduces the quantity of stored data while preserving the ability to identify and print unique files.
Data Source
AI summary
An image forming system includes an information terminal and an image forming apparatus. The image forming apparatus stores a hash value of a file on which image forming operation is to be performed or has been performed. Upon a request to print a predetermined file at the information terminal, the information terminal generates a hash value of the predetermined file. The information terminal transmits print data and the hash value to the image forming apparatus only in the case where the information terminal determines that hash values stored by the image forming apparatus do not include the generated hash value.