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What is the "OCR - Image Reader" add-on and how can I use it?
This extension is about having a simple yet powerful in-page OCR application on hand without installing a native one. The extension is pretty simple to use. Whenever you need to extract the content of an image or a text that cannot be selected, simply press the toolbar button to switch to the area selection mode. Now hold your mouse down and select the area of interest, then release the mouse pointer. At this point, the extension captures the screen area and send this image to the OCR engine. This process happens inside the page in a frame element. You can see the progress of the entire process in a popup window. The first step is to fetch the language training database from the server, then extract the text content out of the image area. Both of these processes have a progress bar. The fetch step might take some time on the first run, but should be fast for all the subsequent calls as your browser should have already cached the resource once.
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What's new in this version?
Please check the Logs section.
Does this extension uses an online service for dong the text recognition?
No the process of extracting the text content out of the image all happens locally. However, note that this extension gets the training data from a remote server since the database is about 30Mbytes and cannot be packed with the extension itself. This extension does not interact with any remote services at all except the database fetching part.
Can I send a very large image to the OCR engine?
Theoretically, you can send large images too, but it is going to take a long time for the extension to process the image. It might even require too much CPU resources to be able to extract the content. It is recommended to use the area selection tool properly to only select the required area instead of having a large image which large empty area around.
What is the OCR engine of this extension?
This extension uses the powerful Tesseract.js with online language training resources to have the latest database
When I am trying to use this extension on local images, I get the "Cannot access contents of the page. Extension manifest must request permission to access the respective host" notification. Is there anyway to use this extension on local images?
You need to create a local server and access images with the "http://127.0.0.1/..." address to be able to use this extension. On modern browsers, no extension can access the FILE scheme. So we are going to access local files with the standard HTTP scheme similar to normal web pages. Read How do you set up a local testing server documentation to set up a local server.
I usually perform OCR on documents in different languages. It would be helpful if this extension could detect the language of the image and use the proper engine. Is this possible?
As of version 0.2.3, it is possible to change the language to auto-detect. If this mode is selected, the extension performs the initial OCR on the image in three different languages (English, Arabic, and Japanese), and uses the output text to detect the content's language using the Compact Language Detector (CLD) algorithm. On successful language detection, the extension uses it to perform the actual OCR. Note that since the extension needs to grab the trained engine for multiple languages, the first detection is slow.
Is it possible to post the OCR result to a server?
As of version 0.2.4, you can define a custom server to post the result. A use case is to copy the data to a local text file without a manual copy and paste process. To configure the server, use Shift + click on the "Post Result" button. General Format:
[GET|POST|PUT]|URL|[POST|PUT body]
Post Example:POST|http://127.0.0.1:8080|&content;
POST|http://127.0.0.1:8080|{"body":"&content"};
Put Example:PUT|http://127.0.0.1:8080|&content;
Get Example:GET|http://127.0.0.1:8080?data=&content;|
Open in a Browser Tab Example:OPEN|http://127.0.0.1:8080?data=&content;|
The "OPEN" command can be used to for instance search the extracted content in a new browser tab or send the content to a website that needs user interaction. The &content;
keyword on the URL part will be replaced with the actual result and it is encoded (encodeURIComponent), but the &content;
on the body section is not altered. You can have one instance of the &content;
keyword in the URL and one instance in the body part. You can write the server code in any language such as Python, PHP, or JavaScript. Here you can find a sample code written in JavaScipt. This code is meant for NodeJS. Alter the code to fit your needs:const http = require('http');
const server = http.createServer(function(req, res) { // 2 - creating server
// res.setHeader('Access-Control-Allow-Origin', '*');
console.log('Request URL: ' + req.url);
console.log('Request method: ' + req.method);
if (req.method === 'GET') {
res.end();
}
else {
req.on('data', chunk => {
console.log('Chunk:', chunk);
});
req.on('end', () => {
res.end();
});
}
});
server.listen(8080);
Supported keywords:&content;
OCR result&href;
Document URL[Version 0.2.7] Is it possible to close all result panels at once?
Use the Shift key while pressing the "Close" button to close all open panels on the current page
Can I translate the extracted text from an image using this extension?
You can use the "Post Result" button to send the extracted text to a translator service. For instance, to send the text to Google Translate and translate any language into English use:
OPEN|https://translate.google.com/?sl=auto&tl=en&text=&content;|
To send the text to DeepL and translate in English, useOPEN|https://www.deepl.com/translator#en/de/&content;|
Please keep reviews clean, avoid improper language, and do not post any personal information. Also, please consider sharing your valuable input on the official store.
Permission | Description |
---|---|
storage | to keep the internal preferences |
activeTab | to inject area select script into the active page after a user action |
notifications | to display possible warnings during the OCR process |