Recognizing text in image archives in Yandex Vision OCR

Use the Yandex Vision OCR service to recognize text in images. You can also store both the source images and recognition results in Yandex Object Storage.

To set up an infrastructure for text recognition using Vision OCR and export the results automatically to Object Storage:

1. Prepare your cloud.
2. Create a bucket.
3. Create a VM.
4. Configure the VM.
5. Create an archive with images.
6. Prepare a script for recognition and uploading of images.
7. Double-check the recognition results.

If you no longer need these resources, delete them.

Before you beginBefore you begin

Sign up in Yandex Cloud and create a billing account:

1. Navigate to the management console and log in to Yandex Cloud or register a new account.
2. On the Yandex Cloud Billing page, make sure you have a billing account linked and it has the ACTIVE or TRIAL_ACTIVE status. If you do not have a billing account, create one and link a cloud to it.

If you have an active billing account, you can navigate to the cloud page to create or select a folder for your infrastructure to operate in.

Learn more about clouds and folders.

Required paid resourcesRequired paid resources

The infrastructure costs for image recognition and data storage include:

• A fee for VM computing resources (see Yandex Compute Cloud pricing).
• A fee for data storage in a bucket and operations with data (see Yandex Object Storage pricing).
• A fee for using a dynamic or a static public IP (see Yandex Virtual Private Cloud pricing).
• A fee for using Yandex Vision OCR (see pricing for Yandex Vision OCR).

Create a bucketCreate a bucket

To create an Object Storage bucket to store the source images and recognition results:

Create a VMCreate a VM

Configure the VMConfigure the VM

Set up the Yandex Cloud CLISet up the Yandex Cloud CLI

1. Connect to the VM via SSH.

2. Install the Yandex Cloud CLI and create a profile.

3. Make sure that the Yandex Cloud CLI runs correctly:

   CLI

   Run the following command on the VM:

   yc config list
   

   Result:

   token: AQ...gs
   cloud-id: b1gdtdqb1900f5rqqvli
   folder-id: b1gveg9vude9g3uioa50
   

   Save the folder-id parameter: you'll need it to set up a service account.

Set up a service accountSet up a service account

Set up the AWS CLISet up the AWS CLI

1. Update the packages installed in the VM operating system. To do this, run the command:

   sudo yum update -y
   

2. Install the AWS CLI:

   sudo yum install awscli -y
   

3. Set up the AWS CLI:

   aws configure
   

   Specify the parameter values:

   • AWS Access Key ID: The ID of the key_id static access key that you generated when setting up the service account.
   • AWS Secret Access Key: The secret key that you generated when setting up the service account.
   • Default region name: ru-central1.
   • Default output format: json.

4. Make sure that the ~/.aws/credentials file contains relevant values for key_id and secret:

   cat ~/.aws/credentials
   

5. Make sure that the ~/.aws/config file contains relevant values for Default region name and Default output format:

   cat ~/.aws/config
   

Create an archive with imagesCreate an archive with images

1. Upload your images that include recognizable text to the bucket.

   Tip

   Use the sample image of the penguin crossing road sign.

2. To make sure that the images were uploaded, use the request with the bucket name:

   aws --endpoint-url=https://storage.yandexcloud.net s3 ls s3://<bucket_name>/
   

3. Save the images from the bucket to the VM, for example, to the my_pictures folder:

   aws --endpoint-url=https://storage.yandexcloud.net s3 cp s3://<bucket_name>/ my_pictures --recursive
   

4. Compress the images into an archive, for example, my_pictures.tar:

   tar -cf my_pictures.tar my_pictures/*
   

5. Delete the image directory:

   rm -rfd my_pictures
   

Prepare a script for digitizing and uploading imagesPrepare a script for digitizing and uploading images

Configure the environmentConfigure the environment

1. Install the jq package. The script will use it to process the results from Vision OCR:

   sudo yum install jq -y
   

2. Install the text editor nano:

   sudo yum install nano -y
   

3. Set the environment variables necessary for the script to run:

   export BUCKETNAME="<bucket_name>"
   export FOLDERID="<folder_id>"
   export IAMTOKEN="<IAM_token>"
   

   Where:

   • BUCKETNAME: The bucket name.
   • FOLDERID: The folder ID.
   • IAMTOKEN: The IAM token that you issued when setting up the service account.

Create a scriptCreate a script

The script includes the following steps:

1. Create the relevant directories.
2. Unpack the archive with images.
3. Process all the images one-by-one:
   1. Base64-encode the image.
   2. Create a request body for the given image.
   3. Send the image in a POST request to Vision OCR for recognition.
   4. Save the result to the output.json file.
   5. Extract the recognized text from output.json and save it to a text file.
4. Add the resulting text files to an archive.
5. Upload the archive with the text files to Object Storage.
6. Delete the auxiliary files.

For your convenience, the text of the script includes comments to each step.

To implement the script:

1. Create a file, for example, vision.sh and open it in the nano text editor:

   sudo nano vision.sh
   

2. Copy the script text to vision.sh:

   #!/bin/bash
   
   # Create the relevant directories
    echo "Creating directories..."
   
   # Create a directory for the recognized text
   mkdir my_pictures_text
   
   # Unpack the archive with images to the created directory
   echo "Extract pictures in my_pictures directory..."
   tar -xf my_pictures.tar
   
   # Recognize the images from the archive
   FILES=my_pictures/*
   for f in $FILES
   # Loop through the files in the directory to run the actions:
   do
       # Base64-encode the image to send it to Vision OCR
       CODEIMG=$(base64 -i $f | cat)
   
       # Create the body.json file to be sent in a POST request to Vision OCR
       cat <<EOF > body.json
   {
   "folderId": "$FOLDERID",
   "analyze_specs": [{
   "content": "$CODEIMG",
   "features": [{
   "type": "TEXT_DETECTION",
   "text_detection_config": {
   "language_codes": ["en","ru"]
   }
   }]
   }]
   }
   EOF
       # Send the image to Vision OCR for recognition and write the result to output.json
       echo "Processing file $f in Vision OCR..."
       curl -X POST --silent \
       -H "Content-Type: application/json" \
       -H "Authorization: Bearer ${IAMTOKEN}" \
       -d '@body.json' \
       https://vision.api.cloud.yandex.net/vision/v1/batchAnalyze > output.json
   
       # Get the image file name to be used below
       IMAGE_BASE_NAME=$(basename -- "$f")
       IMAGE_NAME="${IMAGE_BASE_NAME%.*}"
   
       # Get text data from output.json and write it to a TXT file named identically with the image file
       cat output.json | jq -r '.results[].results[].textDetection.pages[].blocks[].lines[].words[].text' | awk -v ORS=" " '{print}' > my_pictures_text/$IMAGE_NAME".txt"
   done
   
   # Add the directory with the text files to an archive
   echo "Packing text files to archive..."
   tar -cf my_pictures_text.tar my_pictures_text
   
   # Send the text file archive to the bucket
   echo "Sending archive to Object Storage Bucket..."
   aws --endpoint-url=https://storage.yandexcloud.net s3 cp my_pictures_text.tar s3://$BUCKETNAME/ > /dev/null
   
   # Delete the auxiliary files
   echo "Cleaning up..."
   rm -f body.json
   rm -f output.json
   rm -rfd my_pictures
   rm -rfd my_pictures_text
   rm -r my_pictures_text.tar
   

3. Set the permissions to run the script:

   sudo chmod 755 vision.sh
   

4. Run the script:

   ./vision.sh
   

Double-check the recognition resultsDouble-check the recognition results

How to delete created resourcesHow to delete created resources

To stop paying for the resources created:

1. Delete all the objects from the bucket.
2. Delete the respective bucket.
3. Delete the VM.
4. Delete the static public IP if you reserved one.