server-ocr-2.scala

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

        val preProcessed: Source[ByteString, NotUsed] = Source
          .single(image)
          .via(imageToBinaryImage)
          .via(imageDeSkew())
          .via(imageWriter())

        complete(HttpEntity(ContentType.Binary(MediaTypes.`image/png`), preProcessed))
    }
  }
}