# tensorflow::ops::NonMaxSuppressionV4

`#include <image_ops.h>`

Greedily selects a subset of bounding boxes in descending order of score,.

## Summary

pruning away boxes that have high intersection-over-union (IOU) overlap with previously selected boxes. Bounding boxes with score less than `score_threshold` are removed. Bounding boxes are supplied as \[y1, x1, y2, x2\], where (y1, x1) and (y2, x2) are the coordinates of any diagonal pair of box corners and the coordinates can be provided as normalized (i.e., lying in the interval \[0, 1\]) or absolute. Note that this algorithm is agnostic to where the origin is in the coordinate system and more generally is invariant to orthogonal transformations and translations of the coordinate system; thus translating or reflections of the coordinate system result in the same boxes being selected by the algorithm. The output of this operation is a set of integers indexing into the input collection of bounding boxes representing the selected boxes. The bounding box coordinates corresponding to the selected indices can then be obtained using the `tf.gather operation`. For example: selected_indices = tf.image.non_max_suppression_v2( boxes, scores, max_output_size, iou_threshold, score_threshold) selected_boxes = tf.gather(boxes, selected_indices)

Arguments:

- scope: A [Scope](https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/scope#classtensorflow_1_1_scope) object
- boxes: A 2-D float tensor of shape `[num_boxes, 4]`.
- scores: A 1-D float tensor of shape `[num_boxes]` representing a single score corresponding to each box (each row of boxes).
- max_output_size: A scalar integer tensor representing the maximum number of boxes to be selected by non max suppression.
- iou_threshold: A 0-D float tensor representing the threshold for deciding whether boxes overlap too much with respect to IOU.
- score_threshold: A 0-D float tensor representing the threshold for deciding when to remove boxes based on score.

<br />

Optional attributes (see `https://www.tensorflow.org/versions/r2.0/api_docs/cc/struct/tensorflow/ops/non-max-suppression-v4/attrs#structtensorflow_1_1ops_1_1_non_max_suppression_v4_1_1_attrs`):

- pad_to_max_output_size: If true, the output `selected_indices` is padded to be of length `max_output_size`. Defaults to false.

<br />

Returns:

- `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/output#classtensorflow_1_1_output` selected_indices: A 1-D integer tensor of shape `[M]` representing the selected indices from the boxes tensor, where `M <= max_output_size`.
- `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/output#classtensorflow_1_1_output` valid_outputs: A 0-D integer tensor representing the number of valid elements in `selected_indices`, with the valid elements appearing first.

<br />

| ### Constructors and Destructors ||
|---|---|
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1ac241f89469a7188f8d9b5c0daa2441f4(const ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/scope#classtensorflow_1_1_scope & scope, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input boxes, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input scores, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input max_output_size, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input iou_threshold, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input score_threshold)` ||
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1afc8c9e7cedb3678900fa3bcf995aee11(const ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/scope#classtensorflow_1_1_scope & scope, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input boxes, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input scores, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input max_output_size, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input iou_threshold, ::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/input#classtensorflow_1_1_input score_threshold, const https://www.tensorflow.org/versions/r2.0/api_docs/cc/struct/tensorflow/ops/non-max-suppression-v4/attrs#structtensorflow_1_1ops_1_1_non_max_suppression_v4_1_1_attrs & attrs)` ||

| ### Public attributes ||
|---|---|
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1a68c64a50fa3dd5b983f6e09e61b92eab` | `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/operation#classtensorflow_1_1_operation` |
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1a3f301cbbf0cd3b82a64c243b1e357fa6` | `::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/output#classtensorflow_1_1_output` |
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1a47653a5cde7a40dd1801dfc699e2f429` | `::https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/output#classtensorflow_1_1_output` |

| ### Public static functions ||
|---|---|
| `https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4_1a67d61f68bcfca71cdf3f27c979f2ecd2(bool x)` | `https://www.tensorflow.org/versions/r2.0/api_docs/cc/struct/tensorflow/ops/non-max-suppression-v4/attrs#structtensorflow_1_1ops_1_1_non_max_suppression_v4_1_1_attrs` |

| ### Structs ||
|---|---|
| [tensorflow::ops::NonMaxSuppressionV4::Attrs](https://www.tensorflow.org/versions/r2.0/api_docs/cc/struct/tensorflow/ops/non-max-suppression-v4/attrs) | Optional attribute setters for [NonMaxSuppressionV4](https://www.tensorflow.org/versions/r2.0/api_docs/cc/class/tensorflow/ops/non-max-suppression-v4#classtensorflow_1_1ops_1_1_non_max_suppression_v4). |

## Public attributes

### operation

```
Operation operation
```

### selected_indices

```
::tensorflow::Output selected_indices
```

### valid_outputs

```
::tensorflow::Output valid_outputs
```

## Public functions

### NonMaxSuppressionV4

```
 NonMaxSuppressionV4(
  const ::tensorflow::Scope & scope,
  ::tensorflow::Input boxes,
  ::tensorflow::Input scores,
  ::tensorflow::Input max_output_size,
  ::tensorflow::Input iou_threshold,
  ::tensorflow::Input score_threshold
)
```

### NonMaxSuppressionV4

```
 NonMaxSuppressionV4(
  const ::tensorflow::Scope & scope,
  ::tensorflow::Input boxes,
  ::tensorflow::Input scores,
  ::tensorflow::Input max_output_size,
  ::tensorflow::Input iou_threshold,
  ::tensorflow::Input score_threshold,
  const NonMaxSuppressionV4::Attrs & attrs
)
```

## Public static functions

### PadToMaxOutputSize

```
Attrs PadToMaxOutputSize(
  bool x
)
```