bi-ocr.scala

// Add class wrapping String for JSON Streaming
case class OcrString(ocr:String)

def imageOcr = Flow[BufferedImage].map(bi => {
  val ocr = tesseract.doOCR(bi)
  OcrString(ocr)
})

// Update route
path("image" / "ocr") {
  post {
    fileUpload("fileUpload") {
      case (_, fileStream) =>
        val inputStream = fileStream.runWith(StreamConverters.asInputStream())
        val image = ImageIO.read(inputStream)

        val ocr = Source
          .single(image)
          .via(imageToBinaryImage)
          .via(bufferedImageToMat)
          .via(enhanceMat)
          .via(matToBufferedImage)
          .via(imageDeSkew())
          .via(imageOcr)

        complete(ocr)
    }
  }
}

// Add implicit ocrFormat
object MyJsonProtocol
  extends SprayJsonSupport
    with DefaultJsonProtocol {
      implicit val ocrFormat = jsonFormat1(OcrString.apply)
}