Document Scanning Technology and Practice in HarmonyOS Next

This article aims to deeply explore the document scanning technology in the Huawei HarmonyOS Next system (up to API 12 as of now), and summarize it based on practical development practices. It mainly serves as a vehicle for technical sharing and communication. There may be mistakes and omissions. Colleagues are welcome to put forward valuable opinions and questions so that we can make progress together. This article is original content, and any form of reprint must indicate the source and the original author.

I. Principles and Functional Characteristics of Document Scanning Technology

(1) Detailed Explanation of Technical Principles

In the world of document scanning in HarmonyOS Next, its technical principles are like a meticulously crafted work of art.

First is the image acquisition link, which is the basis for obtaining document information. The image of the document is captured through the camera of the device at an appropriate resolution and frame rate. The performance of the camera (such as the number of pixels, focusing ability, etc.) directly affects the quality of the acquired image. For example, a high-pixel camera can capture more details, making the text and graphics in the document clearer. During the acquisition process, it is necessary to ensure that the document is completely within the shooting range and remains stable to avoid image blurring due to shaking.

Next is the image processing stage, which is the core part of the document scanning technology. Image processing includes several key steps:

1. Grayscale Conversion: Convert the color image into a grayscale image, reducing the amount of data while retaining the main information of the document, which is convenient for subsequent processing. For example, after grayscaling a colored contract document, the outlines of the text and graphics are still clearly visible, providing a more concise data basis for subsequent operations.
2. Noise Reduction Processing: Remove the noise interference in the image. Common noises include salt-and-pepper noise (manifested as random black and white dots) and Gaussian noise (making the image blurry), etc. Using filtering algorithms (such as median filtering, Gaussian filtering, etc.) can effectively reduce the noise and make the document image clearer. For example, when scanning an old paper document, there may be noises such as paper texture and stains. Through noise reduction processing, the text and graphics can be highlighted, and the scanning quality can be improved.
3. Edge Detection: Detect the edges of the document through specific algorithms (such as Sobel operator, Canny operator, etc.) to determine the boundaries and content areas of the document. Accurate edge detection is crucial for document correction and cropping. For example, when scanning a paper placed irregularly, edge detection can find the four edges of the paper, providing a basis for subsequently correcting it into a rectangle.
4. Document Correction: According to the results of edge detection, correct the tilted or distorted document to make it horizontal or vertical. This can be achieved through mathematical methods such as affine transformation to ensure that the document content presents a normal perspective in the scanned result, which is convenient for reading and recognition. For example, when the photographed document is tilted at a certain angle, the document correction step can adjust it to a horizontally placed state.

(2) Analysis of the Functional Characteristics of Document Scanning in HarmonyOS Next

HarmonyOS Next has some unique functional characteristics in document scanning. In terms of the types of supported devices, it currently mainly supports mobile phones and tablets. The portability of these devices makes them ideal tools for document scanning. Users can use their devices to scan documents anytime and anywhere, which is convenient and fast. In terms of language support, it covers common languages such as Simplified Chinese and English, which is convenient for users of different languages. For example, in the office scenarios of multinational enterprises, employees can use the document scanning function in different language versions to meet diverse office needs.

(3) Comparison of Different Document Scanning Technologies

1. Traditional Scanning Technology (Based on a Scanner) Traditional scanners have high image quality in document scanning and can provide high-resolution and accurate scanning results. Their scanning accuracy is high, and for some documents with extremely high requirements for details (such as engineering drawings, legal documents, etc.), they can clearly present every detail. However, scanner devices are relatively large in size, not easy to carry, and need to be connected to a computer to be used, so the usage scenarios are relatively limited. Moreover, the scanning speed is relatively slow, and only one page of the document can be scanned each time, which is not suitable for the rapid scanning requirements of a large number of documents.
2. Document Scanning Applications Based on Smartphones (Not HarmonyOS Next) Such applications use the cameras of smartphones to achieve document scanning and have the advantage of strong portability. Users can use their mobile phones to scan at any time. The processing speed is relatively fast, and the scanning results can be generated quickly. However, its image quality is limited by the performance of the mobile phone camera and the shooting environment. Compared with professional scanners, there may be a certain gap in scanning accuracy and image details. For example, when scanning some small fonts or fine charts, blurring or distortion may occur.
3. Document Scanning Technology in HarmonyOS Next The document scanning technology in HarmonyOS Next combines the portability of smartphones and certain image processing advantages. It can quickly complete document scanning while ensuring a certain image quality. By using the hardware acceleration of the device and optimized image processing algorithms, it is competitive in terms of processing speed. At the same time, its deep integration with the HarmonyOS Next system gives it certain advantages in device compatibility and user experience. It can better adapt to different models of HarmonyOS Next devices and provide a simple and easy-to-use operation interface. However, compared with professional scanners, in some extreme cases (such as processing extremely large documents or scanning artworks with extremely high requirements for color accuracy), there may still be some room for improvement in image quality.

II. Development of Document Scanning Functions and Application Examples

(1) Introduction to Implementation Methods and Code Examples (if applicable)

In HarmonyOS Next, although the specific document scanning development library is not clearly mentioned in the document, we can assume that there is a similar function library (similar to OpenCV on other platforms). The following is a simplified conceptual code example to show the basic process of document scanning (assuming libraries and functions):

import { DocumentScannerLibrary } from '@ohos.documentscanner';

// Start document scanning (assuming that the relevant devices and permissions have been initialized)
let scanner = DocumentScannerLibrary.startScanner();

// Get the scanning result (here simplified as a simulated callback function, and actual asynchronous operations may need to be processed)
scanner.on('scanResult', (result) => {
    let scannedImage = result.image;
    // Display or further process the scanning result (such as saving it as a file, etc.)
    console.log('Scanning completed, image size:', scannedImage.width, scannedImage.height);
});

In this example, first, the document scanning function is started, and then the scanning result is obtained through the registered callback function. In actual development, detailed parameter settings and function calls need to be made according to the specific library and API used, including the setting of image acquisition parameters (such as resolution, focusing mode, etc.) and image processing parameters (such as noise reduction intensity, edge detection threshold, etc.) to achieve high-quality document scanning functions.

(2) Demonstration of Practical Application Examples

1. Case of Office Document Scanning In daily office scenarios, users often need to scan various documents, such as contracts, reports, invoices, etc. When using a HarmonyOS Next device to scan documents, the user opens the document scanning application and points the device's camera at the document. The application will automatically detect the edges of the document and perform image acquisition and processing. For example, when scanning a contract document, after the camera captures the document image, the system removes the background noise through the image processing algorithm, enhances the contrast of the text, accurately detects the edges of the document, and corrects it. After the scanning is completed, the user can directly view the high-definition scanned copy on the device, and save or share it after confirming that there are no errors. Compared with traditional scanners, using a HarmonyOS Next device to scan documents is more convenient. There is no need for additional equipment, and the operation can be carried out anytime and anywhere, greatly improving office efficiency.
2. Case of Scanning Learning Materials For students and educators, scanning learning materials is also a common need. For example, students can use a HarmonyOS Next device to scan important chapters, notes, or test papers in textbooks and other materials, and convert them into electronic documents for storage and review. During the scanning process, even in a classroom environment with less than ideal lighting, the system can, through optimized image processing algorithms, minimize the impact of shadows and uneven lighting on the scanning results. The scanned electronic documents can be easily annotated, organized, and classified, which is convenient for learning and knowledge management. Educators can scan students' homework or test papers for electronic marking and archiving, improving the efficiency of teaching management.

(3) Evaluation of Scanning Effects and Analysis of Influencing Factors

1. Evaluation Indicators of Scanning Effects The effect of document scanning is mainly evaluated by the clarity, accuracy, and integrity of the scanned copy. Clarity can be judged by observing whether the edges of the text and graphics are sharp and whether the details are clearly distinguishable. For example, when scanning a technical document with small fonts, a clear scanned copy should allow the reader to easily recognize each character. Accuracy is reflected in the degree of restoration of the document content, including the correct recognition of the text and the accurate presentation of the graphics. Integrity ensures that all the content of the document is scanned completely without omission or missing parts. For example, when scanning a multi-page document, it is necessary to ensure that each page is scanned accurately and in the correct order.
2. Analysis of Influencing Factors The shooting angle has a significant impact on the scanning effect. If the shooting angle is tilted, the document will appear in a trapezoidal or irregular shape in the image, affecting the accuracy of document correction and, in turn, reducing the clarity and accuracy of the scanned copy. For example, when shooting an A4 paper, if the paper is not parallel to the plane of the camera, the text in the scanned image may be deformed. The lighting conditions are also a key factor. Too strong or too weak light will cause problems such as shadows, reflections, or overexposure. In strong light, the document may have reflective areas, making the text difficult to recognize; in a low-light environment, the image may be blurry due to underexposure. In addition, the quality of the document itself (such as the flatness of the paper, color, stains, etc.) will also affect the scanning effect. A wrinkled paper may cause some text to be blocked or deformed, and a stained paper may interfere with text recognition.

III. Optimization of Document Scanning Technology and Innovative Applications

(1) Proposed Optimization Methods

1. Adopt More Advanced Image Processing Algorithms In the image processing stage, image enhancement algorithms based on deep learning can be adopted. For example, use a generative adversarial network (GAN) to enhance the document image. GAN can learn the features of high-quality document images and convert low-quality scanned images into clearer and more realistic images. For noise reduction processing, a denoising network based on deep learning can be used, which can better adapt to different types of noise and better retain the details of the text and graphics while removing the noise. In terms of edge detection, using a deep learning model can more accurately detect the edges of the document, especially in the case of complex backgrounds or partially occluded documents. For example, when scanning a document placed on a textured background, the deep learning edge detection model can more accurately identify the boundaries of the document, improving the accuracy of document correction.
2. Optimize the Settings of Scanning Parameters According to different document types and shooting environments, optimizing the settings of scanning parameters can improve the scanning quality and efficiency. For example, when shooting a document with a lot of text, the resolution can be appropriately increased to ensure the clarity of the text, but it should be noted that too high a resolution will increase the amount of data and processing time. For a dark environment, the exposure time and sensitivity of the camera can be automatically adjusted to reduce the noise while ensuring sufficient brightness. When performing edge detection, the threshold of the edge detection algorithm can be reasonably adjusted according to the size of the document and the expected edge clarity. For example, for a larger-sized document, the edge detection threshold can be appropriately increased to reduce the misdetected edge points and improve the accuracy and speed of edge detection.

(2) Discussion on Innovative Applications

1. Combined Application with Cloud Storage Combining document scanning technology with cloud storage services can provide users with a more convenient document management solution. After completing document scanning on a HarmonyOS Next device, the user can directly upload the scanned copy to a cloud storage platform (such as Huawei Cloud Storage) to achieve document backup and cloud storage. In this way, users can access and manage their scanned documents anytime and anywhere on different devices without worrying about data loss. At the same time, the cloud storage platform can provide functions such as document classification, search, and sharing, which is convenient for users to organize and collaborate on a large number of scanned documents. For example, in a team project, team members can upload the scanned project materials to the shared cloud folder, and other members can view and download them in real time, improving team collaboration efficiency.
2. Integrated Application with Document Management Systems Integrating with document management systems makes document scanning an important part of the document management process. In an enterprise or organization, after employees use a HarmonyOS Next device to scan documents, the scanned copies can be automatically imported into the enterprise's internal document management system and classified, archived, and version-managed according to preset rules. For example, the scanned contract documents can automatically enter the contract management module and be stored classified according to information such as the contract number and signing date. At the same time, the document management system can perform content indexing and keyword extraction on the scanned documents, which is convenient for users to quickly search and retrieve the documents. In addition, combined with a workflow engine, the scanned documents can trigger corresponding business processes, such as approval processes, reimbursement processes, etc., to achieve document-driven business automation.

(3) Experience Summary and Precautions

1. Experience in Solving Device Compatibility Issues During the development of document scanning in HarmonyOS Next, device compatibility issues among different device models may be encountered. Due to the possible differences in the camera performance, hardware configuration, and operating system version of different devices, the scanning effects may be inconsistent or the functions may be abnormal. To solve this problem, extensive device testing should be carried out during the development process, including different brands and models of HarmonyOS Next mobile phones and tablets. According to the characteristics of different devices, optimize the algorithm parameters and functional implementation to ensure that stable and high-quality document scanning functions can be provided on various devices. For example, for some devices with a slow camera focusing speed, functions such as pre-focusing or auxiliary focusing prompts can be adopted to help users obtain clear images.
2. Precautions for User Experience Optimization Paying attention to user experience optimization is the key to the success of document scanning applications. In the design of the operation interface, it should be simple and intuitive, allowing users to easily start scanning, adjust parameters, and obtain scanning results. Provide a real-time preview function so that users can see the scanning effect during the shooting process and adjust the shooting angle and lighting conditions in a timely manner. At the same time, add operation prompts and guidance to help users use the document scanning function correctly, such as prompting users to keep the document flat and avoid reflections. After the scanning is completed, provide a variety of saving and sharing options to facilitate users to send the scanned copy to other applications or devices. For example, users can directly share the scanned copy to applications such as WeChat and email, or save it to the local photo album, specified folder, etc. In addition, considering that users may need to scan multi-page documents, provide a convenient multi-page scanning mode, such as functions like automatic page detection and addition, manual page addition, etc., to improve the efficiency of users scanning multi-page documents. It is hoped that through the introduction of this article, everyone can have a deeper understanding of the document scanning technology in HarmonyOS Next and can better apply this technology in practical development to provide users with a more high-quality and convenient document scanning service. If you encounter other problems in the practice process, you are welcome to communicate and discuss together! Haha!