Cloud Vision API

library(googleAuthR)
library(RCurl)
library(stringi)

# Google AuthR Credentials
options('googleAuthR.client_id' = '[your client id]')
options('googleAuthR.client_secret' = '[your client secret]')

# Input
img_url <- '[Image URL]'
feature <- '[Selected Feature]'

# Define Scope
options('googleAuthR.scopes.selected' = c('https://www.googleapis.com/auth/cloud-platform'))
googleAuthR::gar_auth()

# Create a Google Vision API function
f <- gar_api_generator(baseURI = "https://vision.googleapis.com/v1/images:annotate",
                       http_header = "POST")
# Encode the Image URL
img_url_encoded <- base64Encode(getBinaryURL(img_url), "img_url_encoded")
# Create the JSON request
body <- paste0('{  "requests": [    {   "image": { "content": "',img_url_encoded,'" },"features": [  { "type": "',feature,'" } ],  }    ],}')
# Submit the JOB and retrieve the result
result <- f(the_body = body)

# Check status
status <- result$status_code

# Merge the text result
ocr_text <- paste(result$content$responses$textAnnotations[[1]]$description, sep=' ', collapse=' ')
ocr_text <- stri_replace_all(ocr_text, regex = "\n|\r", replacement = " ")