Lua
Lua
Amazon Rekognition - Detect Text in an Image
See more Amazon Rekognition Examples
Detects text in the input image and converts it into machine-readable text. This example passes theimage as base64-encoded image bytes.Chilkat Lua Downloads
local chilkat = require("chilkat")
local rest = chilkat.Rest.new()
local authAws = chilkat.AuthAws.new()
authAws.access_key = "AWS_ACCESS_KEY"
authAws.secret_key = "AWS_SECRET_KEY"
-- Don't forget to change the region to your particular region. (Also make the same change in the call to Connect below.)
authAws.region = "us-west-2"
authAws.service_name = "rekognition"
-- SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
rest:set_auth_aws(authAws)
-- URL: https://rekognition.us-west-2.amazonaws.com/
local bTls = true
local port = 443
local bAutoReconnect = true
-- Don't forget to change the region domain (us-west-2.amazonaws.com) to your particular region.
local success = rest:connect("rekognition.us-west-2.amazonaws.com", port, bTls, bAutoReconnect)
if not success then
print("ConnectFailReason: " .. rest.connect_fail_reason)
print(rest.last_error_text)
return
end
-- Note: The above code does not need to be repeatedly called for each REST request.
-- The rest object can be setup once, and then many requests can be sent. Chilkat will automatically
-- reconnect within a FullRequest* method as needed. It is only the very first connection that is explicitly
-- made via the Connect method.
-- Load the JPG to be passed as base64 in the JSON.
local bdJpg = chilkat.BinData.new()
success = bdJpg:load_file("qa_data/jpg/monday_keep_smiling.jpg")
if not success then
print("Failed to load the input JPG file.")
return
end
-- We wish to send the following JSON in the body of our HTTP request:
-- {
-- "Image": {
-- "Bytes": "base64_image_bytes"
-- }
-- }
-- Here is the image we used for testing:
-- 
-- Convert binary image bytes to base64.
-- Note: We are explicitly keeping the data inside Chilkat to avoid having to pass large strings
-- as arguments to function calls. This is important for some programming languages.
local sbJpg = chilkat.StringBuilder.new()
bdJpg:get_encoded_sb("base64", sbJpg)
local json = chilkat.JsonObject.new()
json:update_sb("Image.Bytes", sbJpg)
rest:add_header("Content-Type", "application/x-amz-json-1.1")
rest:add_header("X-Amz-Target", "RekognitionService.DetectText")
local sbRequestBody = chilkat.StringBuilder.new()
json:emit_sb(sbRequestBody)
local sbResponseBody = chilkat.StringBuilder.new()
success = rest:full_request_sb("POST", "/", sbRequestBody, sbResponseBody)
if not success then
print(rest.last_error_text)
return
end
local respStatusCode = rest.response_status_code
print("response status code = " .. respStatusCode)
if respStatusCode >= 400 then
print("Response Status Code = " .. respStatusCode)
print("Response Header:")
print(rest.response_header)
print("Response Body:")
print(sbResponseBody:get_as_string())
return
end
local jResp = chilkat.JsonObject.new()
jResp:load_sb(sbResponseBody)
jResp.emit_compact = false
print(jResp:emit())
-- Sample JSON response:
-- (Sample code for parsing the JSON response is shown below)
-- {
-- "TextDetections": [
-- {
-- "Confidence": 95.99308776855469,
-- "DetectedText": "( MONDAY IT'S",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.6399821043014526,
-- "Left": 0.219133198261261,
-- "Top": 0.08677978068590164,
-- "Width": 0.7433173656463623
-- },
-- "Polygon": [
-- {
-- "X": 0.219133198261261,
-- "Y": 0.3588336706161499
-- },
-- {
-- "X": 0.8984103798866272,
-- "Y": 0.08677978068590164
-- },
-- {
-- "X": 0.9624505639076233,
-- "Y": 0.4547080099582672
-- },
-- {
-- "X": 0.2831733524799347,
-- "Y": 0.7267619371414185
-- }
-- ]
-- },
-- "Id": 0,
-- "Type": "LINE"
-- },
-- {
-- "Confidence": 99.70352172851562,
-- "DetectedText": "but keep",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.09703556448221207,
-- "Left": 0.6335319876670837,
-- "Top": 0.5153074264526367,
-- "Width": 0.21070890128612518
-- },
-- "Polygon": [
-- {
-- "X": 0.6355597376823425,
-- "Y": 0.5153074264526367
-- },
-- {
-- "X": 0.8442409038543701,
-- "Y": 0.5266726613044739
-- },
-- {
-- "X": 0.8422132134437561,
-- "Y": 0.6123430132865906
-- },
-- {
-- "X": 0.6335319876670837,
-- "Y": 0.6009777784347534
-- }
-- ]
-- },
-- "Id": 1,
-- "Type": "LINE"
-- },
-- {
-- "Confidence": 99.92333984375,
-- "DetectedText": "Smiling",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.31578224897384644,
-- "Left": 0.5070608258247375,
-- "Top": 0.6086956262588501,
-- "Width": 0.4795433282852173
-- },
-- "Polygon": [
-- {
-- "X": 0.5070608258247375,
-- "Y": 0.6298336386680603
-- },
-- {
-- "X": 0.9808917045593262,
-- "Y": 0.6086956262588501
-- },
-- {
-- "X": 0.9866041541099548,
-- "Y": 0.9033399224281311
-- },
-- {
-- "X": 0.5127732157707214,
-- "Y": 0.9244779348373413
-- }
-- ]
-- },
-- "Id": 2,
-- "Type": "LINE"
-- },
-- {
-- "Confidence": 99.77294158935547,
-- "DetectedText": "IT'S",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.09903381764888763,
-- "Left": 0.668789803981781,
-- "Top": 0.17874395847320557,
-- "Width": 0.1449044644832611
-- },
-- "Polygon": [
-- {
-- "X": 0.668789803981781,
-- "Y": 0.17874395847320557
-- },
-- {
-- "X": 0.8136942386627197,
-- "Y": 0.17874395847320557
-- },
-- {
-- "X": 0.8136942386627197,
-- "Y": 0.2777777910232544
-- },
-- {
-- "X": 0.668789803981781,
-- "Y": 0.2777777910232544
-- }
-- ]
-- },
-- "Id": 5,
-- "ParentId": 0,
-- "Type": "WORD"
-- },
-- {
-- "Confidence": 98.44307708740234,
-- "DetectedText": "MONDAY",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.11112251877784729,
-- "Left": 0.5541401505470276,
-- "Top": 0.3526569902896881,
-- "Width": 0.39013487100601196
-- },
-- "Polygon": [
-- {
-- "X": 0.5541401505470276,
-- "Y": 0.3526569902896881
-- },
-- {
-- "X": 0.9442675113677979,
-- "Y": 0.3502415418624878
-- },
-- {
-- "X": 0.9458598494529724,
-- "Y": 0.4613526463508606
-- },
-- {
-- "X": 0.5541401505470276,
-- "Y": 0.4637681245803833
-- }
-- ]
-- },
-- "Id": 4,
-- "ParentId": 0,
-- "Type": "WORD"
-- },
-- {
-- "Confidence": 99.61898803710938,
-- "DetectedText": "but",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.06521739065647125,
-- "Left": 0.6353503465652466,
-- "Top": 0.5241546034812927,
-- "Width": 0.0843949019908905
-- },
-- "Polygon": [
-- {
-- "X": 0.6353503465652466,
-- "Y": 0.5241546034812927
-- },
-- {
-- "X": 0.7197452187538147,
-- "Y": 0.5241546034812927
-- },
-- {
-- "X": 0.7197452187538147,
-- "Y": 0.5893719792366028
-- },
-- {
-- "X": 0.6353503465652466,
-- "Y": 0.5893719792366028
-- }
-- ]
-- },
-- "Id": 6,
-- "ParentId": 1,
-- "Type": "WORD"
-- },
-- {
-- "Confidence": 99.78804779052734,
-- "DetectedText": "keep",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.07971014827489853,
-- "Left": 0.7308917045593262,
-- "Top": 0.5265700221061707,
-- "Width": 0.1114649698138237
-- },
-- "Polygon": [
-- {
-- "X": 0.7308917045593262,
-- "Y": 0.5265700221061707
-- },
-- {
-- "X": 0.8423566818237305,
-- "Y": 0.5265700221061707
-- },
-- {
-- "X": 0.8423566818237305,
-- "Y": 0.6062802076339722
-- },
-- {
-- "X": 0.7308917045593262,
-- "Y": 0.6062802076339722
-- }
-- ]
-- },
-- "Id": 7,
-- "ParentId": 1,
-- "Type": "WORD"
-- },
-- {
-- "Confidence": 89.76324462890625,
-- "DetectedText": "(",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.16401274502277374,
-- "Left": 0.27229300141334534,
-- "Top": 0.6642512083053589,
-- "Width": 0.2850286066532135
-- },
-- "Polygon": [
-- {
-- "X": 0.27229300141334534,
-- "Y": 0.6642512083053589
-- },
-- {
-- "X": 0.2707006335258484,
-- "Y": 0.37922704219818115
-- },
-- {
-- "X": 0.43471336364746094,
-- "Y": 0.37922704219818115
-- },
-- {
-- "X": 0.4363057315349579,
-- "Y": 0.6642512083053589
-- }
-- ]
-- },
-- "Id": 3,
-- "ParentId": 0,
-- "Type": "WORD"
-- },
-- {
-- "Confidence": 99.92333984375,
-- "DetectedText": "Smiling",
-- "Geometry": {
-- "BoundingBox": {
-- "Height": 0.294724702835083,
-- "Left": 0.5079618096351624,
-- "Top": 0.6304348111152649,
-- "Width": 0.4734293222427368
-- },
-- "Polygon": [
-- {
-- "X": 0.5079618096351624,
-- "Y": 0.6304348111152649
-- },
-- {
-- "X": 0.9808917045593262,
-- "Y": 0.6086956262588501
-- },
-- {
-- "X": 0.9856687784194946,
-- "Y": 0.9033816456794739
-- },
-- {
-- "X": 0.512738823890686,
-- "Y": 0.9227052927017212
-- }
-- ]
-- },
-- "Id": 8,
-- "ParentId": 2,
-- "Type": "WORD"
-- }
-- ],
-- "TextModelVersion": "3.0"
-- }
--
--
-- Sample code for parsing the JSON response...
-- Use the following online tool to generate parsing code from sample JSON:
-- Generate Parsing Code from JSON
local Confidence = ""
local DetectedText = ""
local GeometryBoundingBoxHeight = ""
local GeometryBoundingBoxLeft = ""
local GeometryBoundingBoxTop = ""
local GeometryBoundingBoxWidth = ""
local Id = 0
local v_Type = ""
local ParentId = 0
local j = 0
local count_j = 0
local X = ""
local Y = ""
local TextModelVersion = jResp:string_of("TextModelVersion")
local i = 0
local count_i = jResp:size_of_array("TextDetections")
while i < count_i do
jResp.i = i
Confidence = jResp:string_of("TextDetections[i].Confidence")
DetectedText = jResp:string_of("TextDetections[i].DetectedText")
GeometryBoundingBoxHeight = jResp:string_of("TextDetections[i].Geometry.BoundingBox.Height")
GeometryBoundingBoxLeft = jResp:string_of("TextDetections[i].Geometry.BoundingBox.Left")
GeometryBoundingBoxTop = jResp:string_of("TextDetections[i].Geometry.BoundingBox.Top")
GeometryBoundingBoxWidth = jResp:string_of("TextDetections[i].Geometry.BoundingBox.Width")
Id = jResp:int_of("TextDetections[i].Id")
v_Type = jResp:string_of("TextDetections[i].Type")
ParentId = jResp:int_of("TextDetections[i].ParentId")
j = 0
count_j = jResp:size_of_array("TextDetections[i].Geometry.Polygon")
while j < count_j do
jResp.j = j
X = jResp:string_of("TextDetections[i].Geometry.Polygon[j].X")
Y = jResp:string_of("TextDetections[i].Geometry.Polygon[j].Y")
j = j + 1
end
i = i + 1
end