1. Ditch std::unique_ptr, use FrameBuffer directly.

2. Use old Postprocess API

Author: jonpsy

tensorflow_lite_support/cc/task/vision/image_transformer.cc

@@ -152,8 +152,9 @@ StatusOr<FrameBuffer> ImageTransformer::Transform(
   return InferWithFallback(frame_buffer, roi);
 }
 
-StatusOr<std::unique_ptr<FrameBuffer>> ImageTransformer::Postprocess() {
-  std::unique_ptr<FrameBuffer> postprocessed_frame_buffer;
+StatusOr<FrameBuffer> ImageTransformer::Postprocess(
+    const std::vector<const TfLiteTensor*>& /*output_tensors*/,
+    const FrameBuffer& /*frame_buffer*/, const BoundingBox& /*roi*/) {
   const int kRgbPixelBytes = 3;
   const TfLiteTensor* output_tensor =
       TfLiteEngine::GetOutput(GetTfLiteEngine()->interpreter(), 0);
@@ -171,9 +172,9 @@ StatusOr<std::unique_ptr<FrameBuffer>> ImageTransformer::Postprocess() {
           "Size mismatch or unsupported padding bytes between pixel data "
           "and output tensor.");
     }
-
-    postprocessed_data.insert(postprocessed_data.end(), &output_tensor[0],
-                              &output_tensor[output_byte_size / sizeof(uint8)]);
+    const uint8* output_data = AssertAndReturnTypedTensor<uint8>(output_tensor);
+    postprocessed_data.insert(postprocessed_data.end(), &output_data[0],
+                              &output_data[output_byte_size / sizeof(uint8)]);
   } else {  // Denormalize to [0, 255] range.
     if (output_tensor->bytes / sizeof(float) !=
         output_byte_size / sizeof(uint8)) {
@@ -213,11 +214,12 @@ StatusOr<std::unique_ptr<FrameBuffer>> ImageTransformer::Postprocess() {
       /*buffer=*/postprocessed_data.data(),
       /*stride=*/{output_tensor->dims->data[2] * kRgbPixelBytes,
                   kRgbPixelBytes}};
-  postprocessed_frame_buffer = FrameBuffer::Create(
+  auto postprocessed_frame_buffer = FrameBuffer::Create(
       {postprocessed_plane}, to_buffer_dimension, FrameBuffer::Format::kRGB,
       FrameBuffer::Orientation::kTopLeft);
 
-  return postprocessed_frame_buffer;
+  FrameBuffer postprocessed_result = *postprocessed_frame_buffer.get();
+  return postprocessed_result;
 }
 }  // namespace vision
 }  // namespace task

tensorflow_lite_support/cc/task/vision/image_transformer.h

@@ -61,7 +61,7 @@ namespace vision {
 // A CLI demo tool is available for easily trying out this API, and provides
 // example usage. See:
 // examples/task/vision/desktop/image_classifier_demo.cc
-class ImageTransformer : public BaseVisionTaskApi<::tflite::task::vision::FrameBuffer> {
+class ImageTransformer : public BaseVisionTaskApi<FrameBuffer> {
  public:
   using BaseVisionTaskApi::BaseVisionTaskApi;
 
@@ -85,7 +85,7 @@ class ImageTransformer : public BaseVisionTaskApi<::tflite::task::vision::FrameB
   //   only supported colorspace for now),
   // - rotate it according to its `Orientation` so that inference is performed
   //   on an "upright" image.
-  tflite::support::StatusOr<::tflite::task::vision::FrameBuffer> Transform(
+  tflite::support::StatusOr<FrameBuffer> Transform(
       const FrameBuffer& frame_buffer);
 
   // Same as above, except that the transformation is performed based on the
@@ -99,15 +99,17 @@ class ImageTransformer : public BaseVisionTaskApi<::tflite::task::vision::FrameB
   // `frame_buffer` data before any `Orientation` flag gets applied. Also, the
   // region of interest is not clamped, so this method will return a non-ok
   // status if the region is out of these bounds.
-  tflite::support::StatusOr<::tflite::task::vision::FrameBuffer> Transform(
+  tflite::support::StatusOr<FrameBuffer> Transform(
       const FrameBuffer& frame_buffer, const BoundingBox& roi);
 
  protected:
   // The options used to build this ImageTransformer.
   std::unique_ptr<ImageTransformerOptions> options_;
 
   // Post-processing to transform the raw model outputs into image results.
-  tflite::support::StatusOr<std::unique_ptr<::tflite::task::vision::FrameBuffer>> Postprocess();
+  tflite::support::StatusOr<FrameBuffer> Postprocess(
+      const std::vector<const TfLiteTensor*>& output_tensors,
+      const FrameBuffer& frame_buffer, const BoundingBox& roi) override;
 
   // Performs sanity checks on the provided ImageTransformerOptions.
   static absl::Status SanityCheckOptions(const ImageTransformerOptions& options);