ocrworker

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 Go to latest Published: May 1, 2019 License: Apache-2.0 Imports: 17 Imported by: 6

README

GoDoc

OpenOCR makes it simple to host your own OCR REST API.

The heavy lifting OCR work is handled by Tesseract OCR.

Docker is used to containerize the various components of the service.

screenshot

Features

  • Scalable message passing architecture via RabbitMQ.
  • Platform independence via Docker containers.
  • Kubernetes support: workers can run in a Kubernetes Replication Controller
  • Supports 31 languages in addition to English
  • Ability to use an image pre-processing chain. An example using Stroke Width Transform is provided.
  • PDF support via a PDF preprocessor
  • Pass arguments to Tesseract such as character whitelist and page segment mode.
  • REST API docs
  • A Go REST client is available.

Launching OpenOCR on a Docker PAAS

OpenOCR can easily run on any PAAS that supports Docker containers. Here are the instructions for a few that have already been tested:

If your preferred PAAS isn't listed, please open a Github issue to request instructions.

Launching OpenOCR on Ubuntu 14.04

OpenOCR can be launched on anything that supports Docker, such as Ubuntu 14.04.

Here's how to install it from scratch and verify that it's working correctly.

Install Docker

See Installing Docker on Ubuntu instructions.

Find out your host address

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 08:00:27:43:40:c7
          inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0
          ...

The ip address 10.0.2.15 will be used as the RABBITMQ_HOST env variable below.

Launching OpenOCR command run.sh

  • Install docker
  • Install docker-compose
  • git clone https://github.com/tleyden/open-ocr.git
  • cd open-ocr/docker-compose
  • Type ./run.sh (in case you don't have execute right type sudo chmod +x run.sh
  • The runner will ask you if you want to delete the images (choose y or n for each)
  • The runner will ask you to choose between version 1 and 2
    • Version 1 is using the ocr Tesseract 3.04. The memory usage is light. It is pretty fast and not costly in term of size (a simple aws instance with 1GB of ram and 8GB of storage is sufficiant). Result are acceptable
    • Version 2 is using the ocr Tesseract 4.00. The memory usage is light. It is less fast than tesseract 3 and more costly in term of size (an simple aws instance with 1GB of ram is sufficient but with an EBS of 16GB of storage). Result are really better compared to version 3.04.
    • To see a comparative you can have a look to the official page of tesseract

You can use the docker-compose without the run.sh. For this just do:

# for v1
export OPEN_OCR_INSTANCE=open-ocr

# for v2
export OPEN_OCR_INSTANCE=open-ocr-2

# then up (with -d to start it as deamon)
docker-compose up

Docker Compose will start four docker instances

You are now ready to decode images → text via your REST API.

Launching OpenOCR with Docker Compose on OSX

  • Install docker
  • Install docker toolbox
  • Checkout OpenOCR repository
  • cd docker-compose directory
  • docker-machine start default
  • docker-machine env
  • Look at the Docker host IP address
  • Run docker-compose up -d to run containers as daemons or docker-compose up to see the log in console

How to test the REST API after turning on the docker-compose up

Where IP_ADDRESS_OF_DOCKER_HOST is what you saw when you run docker-machine env (e.g. 192.168.99.100) and where HTTP_POST is the port number inside the .yml file inside the docker-compose directory presuming it should be the same 9292.

Request

$ curl -X POST -H "Content-Type: application/json" -d '{"img_url":"http://bit.ly/ocrimage","engine":"tesseract"}' http://IP_ADDRESS_OF_DOCKER_HOST:HTTP_PORT/ocr

Assuming the values are (192.168.99.100 and 9292 respectively)

$ curl -X POST -H "Content-Type: application/json" -d '{"img_url":"http://bit.ly/ocrimage","engine":"tesseract"}' http://192.168.99.100:9292/ocr

Response

It will return the decoded text for the test image:

< HTTP/1.1 200 OK
< Date: Tue, 13 May 2014 16:18:50 GMT
< Content-Length: 283
< Content-Type: text/plain; charset=utf-8
<
You can create local variables for the pipelines within the template by
prefixing the variable name with a “$" sign. Variable names have to be
composed of alphanumeric characters and the underscore. In the example
below I have used a few variations that work for variable names.

Test the REST API

With image url

Request

$ curl -X POST -H "Content-Type: application/json" -d '{"img_url":"http://bit.ly/ocrimage","engine":"tesseract"}' http://10.0.2.15:$HTTP_PORT/ocr

Response

It will return the decoded text for the test image:

< HTTP/1.1 200 OK
< Date: Tue, 13 May 2014 16:18:50 GMT
< Content-Length: 283
< Content-Type: text/plain; charset=utf-8
<
You can create local variables for the pipelines within the template by
prefixing the variable name with a “$" sign. Variable names have to be
composed of alphanumeric characters and the underscore. In the example
below I have used a few variations that work for variable names.

With image base64

Request

$ curl -X POST -H "Content-Type: application/json" -d '{"img_base64":"<YOUR BASE 64 HERE>","engine":"tesseract"}' http://10.0.2.15:$HTTP_PORT/ocr

The REST API also supports:

  • Uploading the image content via multipart/related, rather than passing an image URL. (example client code provided in the Go REST client)
  • Tesseract config vars (eg, equivalent of -c arguments when using Tesseract via the command line) and Page Seg Mode
  • Ability to use an image pre-processing chain, eg Stroke Width Transform.
  • Non-English languages

See the REST API docs and the Go REST client for details.

Client Libraries

These client libraries make it easier to invoke the REST API:

Uploading local files using curl

The supplied docs/upload-local-file.sh provides an example of how to upload a local file using curl with multipart/related encoding of the json and image data:

  • usage: docs/upload-local-file.sh <urlendpoint> <file> [mimetype]
  • download the example ocr image wget http://bit.ly/ocrimage
  • example: docs/upload-local-file.sh http://10.0.2.15:$HTTP_PORT/ocr-file-upload ocrimage

Community

License

OpenOCR is Open Source and available under the Apache 2 License.

Documentation

Index

Constants

View Source 
const (
	ENGINE_TESSERACT = OcrEngineType(iota)
	ENGINE_GO_TESSERACT
	ENGINE_MOCK
)
View Source 
const MOCK_ENGINE_RESPONSE = "mock engine decoder response"
View Source 
const PreprocessorConvertPdf = "convert-pdf"
View Source 
const PreprocessorIdentity = "identity"
View Source 
const PreprocessorStrokeWidthTransform = "stroke-width-transform"
View Source 
const (
	RPC_RESPONSE_TIMEOUT = time.Second * 120
)

Variables

This section is empty.

Functions

This section is empty.

Types

type ConvertPdf 

type ConvertPdf struct {
}

type FlagFunction 

type FlagFunction func()

func NoOpFlagFunction 

func NoOpFlagFunction() FlagFunction

type IdentityPreprocessor 

type IdentityPreprocessor struct {
}

type MockEngine 

type MockEngine struct {
}

func (MockEngine) ProcessRequest 

func (m MockEngine) ProcessRequest(ocrRequest OcrRequest) (OcrResult, error)

type OcrEngine 

type OcrEngine interface {
	ProcessRequest(ocrRequest OcrRequest) (OcrResult, error)
}

func NewOcrEngine 

func NewOcrEngine(engineType OcrEngineType) OcrEngine

type OcrEngineType 

type OcrEngineType int

func (OcrEngineType) String 

func (e OcrEngineType) String() string

func (*OcrEngineType) UnmarshalJSON 

func (e *OcrEngineType) UnmarshalJSON(b []byte) (err error)

type OcrHttpHandler 

type OcrHttpHandler struct {
	RabbitConfig RabbitConfig
}

func NewOcrHttpHandler 

func NewOcrHttpHandler(r RabbitConfig) *OcrHttpHandler

func (*OcrHttpHandler) ServeHTTP 

func (s *OcrHttpHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)

type OcrHttpMultipartHandler 

type OcrHttpMultipartHandler struct {
	RabbitConfig RabbitConfig
}

func NewOcrHttpMultipartHandler 

func NewOcrHttpMultipartHandler(r RabbitConfig) *OcrHttpMultipartHandler

func (*OcrHttpMultipartHandler) ServeHTTP 

func (s *OcrHttpMultipartHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)

type OcrRequest 

type OcrRequest struct {
	ImgUrl            string                 `json:"img_url"`
	ImgBase64         string                 `json:"img_base64"`
	EngineType        OcrEngineType          `json:"engine"`
	ImgBytes          []byte                 `json:"img_bytes"`
	PreprocessorChain []string               `json:"preprocessors"`
	PreprocessorArgs  map[string]interface{} `json:"preprocessor-args"`
	EngineArgs        map[string]interface{} `json:"engine_args"`

	// decode ocr in http handler rather than putting in queue
	InplaceDecode bool `json:"inplace_decode"`
}

func (OcrRequest) String 

func (o OcrRequest) String() string

type OcrResult 

type OcrResult struct {
	Text string
}

func HandleOcrRequest 

func HandleOcrRequest(ocrRequest OcrRequest, rabbitConfig RabbitConfig) (OcrResult, error)

type OcrRpcClient 

type OcrRpcClient struct {
	// contains filtered or unexported fields
}

func NewOcrRpcClient 

func NewOcrRpcClient(rc RabbitConfig) (*OcrRpcClient, error)

func (*OcrRpcClient) DecodeImage 

func (c *OcrRpcClient) DecodeImage(ocrRequest OcrRequest) (OcrResult, error)

type OcrRpcWorker 

type OcrRpcWorker struct {
	Done chan error
	// contains filtered or unexported fields
}

func NewOcrRpcWorker 

func NewOcrRpcWorker(rc RabbitConfig) (*OcrRpcWorker, error)

func (OcrRpcWorker) Run 

func (w OcrRpcWorker) Run() error

func (*OcrRpcWorker) Shutdown 

func (w *OcrRpcWorker) Shutdown() error

type Preprocessor 

type Preprocessor interface {
	// contains filtered or unexported methods
}

type PreprocessorRpcWorker 

type PreprocessorRpcWorker struct {
	Done chan error
	// contains filtered or unexported fields
}

func NewPreprocessorRpcWorker 

func NewPreprocessorRpcWorker(rc RabbitConfig, preprocessor string) (*PreprocessorRpcWorker, error)

func (PreprocessorRpcWorker) Run 

func (w PreprocessorRpcWorker) Run() error

func (*PreprocessorRpcWorker) Shutdown 

func (w *PreprocessorRpcWorker) Shutdown() error

type RabbitConfig 

type RabbitConfig struct {
	AmqpURI      string
	Exchange     string
	ExchangeType string
	RoutingKey   string
	Reliable     bool
}

func DefaultConfigFlagsOverride 

func DefaultConfigFlagsOverride(flagFunction FlagFunction) RabbitConfig

func DefaultTestConfig 

func DefaultTestConfig() RabbitConfig

type StrokeWidthTransformer 

type StrokeWidthTransformer struct {
}

type TesseractEngine 

type TesseractEngine struct {
}

This variant of the TesseractEngine calls tesseract via exec

func (TesseractEngine) ProcessRequest 

func (t TesseractEngine) ProcessRequest(ocrRequest OcrRequest) (OcrResult, error)

type TesseractEngineArgs 

type TesseractEngineArgs struct {
	// contains filtered or unexported fields
}

func NewTesseractEngineArgs 

func NewTesseractEngineArgs(ocrRequest OcrRequest) (*TesseractEngineArgs, error)

func (TesseractEngineArgs) Export 

func (t TesseractEngineArgs) Export() []string

return a slice that can be passed to tesseract binary as command line args, eg, ["-c", "tessedit_char_whitelist=0123456789", "-c", "foo=bar"]

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