86 строки
4.5 KiB
Markdown
86 строки
4.5 KiB
Markdown
# Azure Batch OCR job template
|
|
|
|
This sample shows how to use `ghostscript` and `tesseract-ocr` to transform PDF files into plain text files (`.txt`). It does this in two stages:
|
|
|
|
1. Use [`ghostscript`](https://ghostscript.com/) to convert a PDF to a set of PNG files (one for each page of the PDF).
|
|
2. Use [`tesseract-ocr`](https://github.com/tesseract-ocr) to convert the PNG images into plain text files (`.txt`).
|
|
|
|
## Features used by this sample
|
|
|
|
* [Pool and job templates with parameterization](../../doc/templates.md)
|
|
* [Parametric sweep task factory](../../doc/taskFactories.md#parametric-sweep)
|
|
* [Automatic persistence of task output files to Azure Storage](../../doc/outputFiles.md)
|
|
* [Easy software installation via package managers](../../doc/packages.md)
|
|
|
|
## Prerequisites
|
|
|
|
You must have an Azure Batch account set up with a linked Azure Storage account.
|
|
|
|
## Create a pool
|
|
|
|
To create your pool:
|
|
|
|
```bash
|
|
az batch pool create --template pool.json
|
|
```
|
|
|
|
The default settings in `pool.json` specify a pool named `ocrpool` containing **3** **STANDARD_D1_V2** virtual machines.
|
|
|
|
If you want to change the default values of the pool creation, you can create a JSON file to supply the parameters of your pool. If you have a large number of files to convert, you should use a larger pool or bigger VMs in the pool.
|
|
|
|
In order to create the pool with your own configurations, run:
|
|
```bash
|
|
az batch pool create --template pool.json --parameters <your settings JSON file>
|
|
```
|
|
|
|
**You are billed for your Azure Batch pools, so don't forget to delete this pool through the [Azure portal](https://portal.azure.com) when you're done.**
|
|
|
|
## Upload files
|
|
|
|
To upload your PDF files:
|
|
|
|
```bash
|
|
az batch file upload --local-path <path> --file-group <group>
|
|
```
|
|
|
|
Run this command on a folder containing the PDF files you want to process.
|
|
|
|
## Create a job and tasks
|
|
|
|
Edit the `job.parameters.json` file to supply parameters to the template. If you want to configure other options of the job, such as the the pool id, you can look in the `job.json` parameters section to see what options are available.
|
|
|
|
|
|
| Parameter | Required | Description |
|
|
| -------------------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
|
|
| jobId | Mandatory | The id of the Azure Batch job. |
|
|
| poolId | Optional | The id of the Azure Batch pool to run on. <br/> Must match the id of the pool you created earlier. <br/> Default value if not otherwise specified: `ocrpool` |
|
|
| inputFileGroup | Mandatory | The file group containing the input files. <br/> Must match the name of the file group used by your `az batch file upload` command earlier. |
|
|
| outputFileStorageUrl | Mandatory | A storage SAS URL to a **container** with write access. <br/> A general SAS url to blob storage will not work. |
|
|
|
|
|
|
## Run the job
|
|
|
|
To create your job and tasks:
|
|
```bash
|
|
az batch job create --template job.json --parameters job.parameters.json
|
|
```
|
|
|
|
The outputs of the tasks will be uploaded to the Azure Storage container which you specified as the individual tasks complete.
|
|
The target container will contain a new virtual directory for each task that ran.
|
|
|
|
## Monitor the job
|
|
|
|
You can use this command to monitor the tasks in the job and their progress:
|
|
``` bash
|
|
az batch task list --job-id <jobid>`
|
|
```
|
|
You can also use the [Azure portal](https://portal.azure.com) or [Batch Explorer](https://github.com/Azure/azure-batch-samples/tree/master/CSharp/BatchExplorer) for monitoring.
|
|
|
|
## Structure of the sample
|
|
|
|
| File | Content |
|
|
| --------------------- | ------------------------------------------------------------------------------------------------------ |
|
|
| `pool.json` | A template for creating the pool required for OCR processing. |
|
|
| `job.json` | A template for the job to run, including parameter definitions and a **parametricSweep** task factory. |
|
|
| `job.parameters.json` | Provides values for the parameters defined in `job.json`. |
|