# TensorFlow Lite Optimizing Converter command-line examples

This page provides examples on how to use TOCO via command line. It is
complemented by the following documents:

*   [README](../README.md)
*   [Command-line glossary](cmdline_reference.md)
*   [Python API examples](python_api.md)

Table of contents:

*   [Command-line tools](#tools)
    *   [Converting models prior to TensorFlow 1.9.](#pre-tensorflow-1.9)
*   [Basic examples](#basic)
    *   [Convert a TensorFlow GraphDef](#graphdef)
    *   [Convert a TensorFlow SavedModel](#savedmodel)
    *   [Convert a tf.keras model](#keras)
*   [Quantization](#quantization)
    *   [Convert a TensorFlow GraphDef for quantized inference](#graphdef-quant)
    *   [Use "dummy-quantization" to try out quantized inference on a float
        graph](#dummy-quant)
*   [Specifying input and output arrays](#specifying-input-and-output-arrays)
    *   [Multiple input arrays](#multiple-input-arrays)
    *   [Multiple output arrays](#multiple-output-arrays)
    *   [Specifying subgraphs](#specifying-subgraphs)
*   [Graph visualizations](#graph-visualizations)
    *   [Using --output_format=GRAPHVIZ_DOT](#using-output-format-graphviz-dot)
    *   [Using --dump_graphviz_dir](#using-dump-graphviz-dir)
    *   [Graph "video" logging](#graph-video-logging)
    *   [Legend for the graph visualizations](#graphviz-legend)

## Command-line tools <a name="tools"></a>

There are two approaches to running TOCO via command line.

*   `tflite_convert`: Starting from TensorFlow 1.9, the command-line tool
    `tflite_convert` will be installed as part of the Python package. All of the
    examples below use `tflite_convert` for simplicity.
    *   Example: `tflite_convert --output_file=...`
*   `bazel`: In order to run the latest version of TOCO, [clone the TensorFlow
    repository](https://www.tensorflow.org/install/install_sources#clone_the_tensorflow_repository)
    and use `bazel`. This is the recommended approach for converting models that
    utilize new features that were not supported by TOCO in TensorFlow 1.9.
    *   Example: `bazel run
        //tensorflow/contrib/lite/python:tflite_convert --
        --output_file=...`

### Converting models prior to TensorFlow 1.9. <a name="pre-tensorflow-1.9"></a>

The recommended approach for using TOCO prior to TensorFlow 1.9 is the [Python
API](python_api.md#pre-tensorflow-1.9). If a command line tool is desired, the
`toco` command line tool was available in TensorFlow 1.7. Enter `toco --help` in
Terminal for additional details on the command-line flags available. There were
no command line tools in TensorFlow 1.8.

## Basic examples <a name="basic"></a>

The following section shows examples of how to convert a basic float-point model
from each of the supported data formats into a TensorFlow Lite FlatBuffers.

### Convert a TensorFlow GraphDef <a name="graphdef"></a>

The follow example converts a basic TensorFlow GraphDef (frozen by
[freeze_graph.py](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/tools/freeze_graph.py))
into a TensorFlow Lite FlatBuffer to perform floating-point inference. Frozen
graphs contain the variables stored in Checkpoint files as Const ops.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/mobilenet_v1_0.50_128_frozen.tgz \
  | tar xzv -C /tmp
tflite_convert \
  --output_file=/tmp/foo.tflite \
  --graph_def_file=/tmp/mobilenet_v1_0.50_128/frozen_graph.pb \
  --input_arrays=input \
  --output_arrays=MobilenetV1/Predictions/Reshape_1
```

The value for `input_shapes` is automatically determined whenever possible.

### Convert a TensorFlow SavedModel <a name="savedmodel"></a>

The follow example converts a basic TensorFlow SavedModel into a Tensorflow Lite
FlatBuffer to perform floating-point inference.

```
tflite_convert \
  --output_file=/tmp/foo.tflite \
  --saved_model_dir=/tmp/saved_model
```

[SavedModel](https://www.tensorflow.org/guide/saved_model#using_savedmodel_with_estimators)
has fewer required flags than frozen graphs due to access to additional data
contained within the SavedModel. The values for `--input_arrays` and
`--output_arrays` are an aggregated, alphabetized list of the inputs and outputs
in the [SignatureDefs](https://www.tensorflow.org/serving/signature_defs) within
the
[MetaGraphDef](https://www.tensorflow.org/guide/saved_model#apis_to_build_and_load_a_savedmodel)
specified by `--saved_model_tag_set`. As with the GraphDef, the value for
`input_shapes` is automatically determined whenever possible.

There is currently no support for MetaGraphDefs without a SignatureDef or for
MetaGraphDefs that use the [`assets/`
directory](https://www.tensorflow.org/guide/saved_model#structure_of_a_savedmodel_directory).

### Convert a tf.Keras model <a name="keras"></a>

The following example converts a `tf.keras` model into a TensorFlow Lite
Flatbuffer. The `tf.keras` file must contain both the model and the weights.

```
tflite_convert \
  --output_file=/tmp/foo.tflite \
  --keras_model_file=/tmp/keras_model.h5
```

## Quantization

### Convert a TensorFlow GraphDef for quantized inference <a name="graphdef-quant"></a>

TOCO is compatible with fixed point quantization models described
[here](https://www.tensorflow.org/performance/quantization). These are float
models with
[`FakeQuant*`](https://www.tensorflow.org/api_guides/python/array_ops#Fake_quantization)
ops inserted at the boundaries of fused layers to record min-max range
information. This generates a quantized inference workload that reproduces the
quantization behavior that was used during training.

The following command generates a quantized TensorFlow Lite FlatBuffer from a
"quantized" TensorFlow GraphDef.

```
tflite_convert \
  --output_file=/tmp/foo.tflite \
  --graph_def_file=/tmp/some_quantized_graph.pb \
  --inference_type=QUANTIZED_UINT8 \
  --input_arrays=input \
  --output_arrays=MobilenetV1/Predictions/Reshape_1 \
  --mean_values=128 \
  --std_dev_values=127
```

### Use \"dummy-quantization\" to try out quantized inference on a float graph <a name="dummy-quant"></a>

In order to evaluate the possible benefit of generating a quantized graph, TOCO
allows "dummy-quantization" on float graphs. The flags `--default_ranges_min`
and `--default_ranges_max` accept plausible values for the min-max ranges of the
values in all arrays that do not have min-max information. "Dummy-quantization"
will produce lower accuracy but will emulate the performance of a correctly
quantized model.

The example below contains a model using Relu6 activation functions. Therefore,
a reasonable guess is that most activation ranges should be contained in [0, 6].

```
curl https://storage.googleapis.com/download.tensorflow.org/models/mobilenet_v1_0.50_128_frozen.tgz \
  | tar xzv -C /tmp
tflite_convert \
  --output_file=/tmp/foo.cc \
  --graph_def_file=/tmp/mobilenet_v1_0.50_128/frozen_graph.pb \
  --inference_type=QUANTIZED_UINT8 \
  --input_arrays=input \
  --output_arrays=MobilenetV1/Predictions/Reshape_1 \
  --default_ranges_min=0 \
  --default_ranges_max=6 \
  --mean_values=128 \
  --std_dev_values=127
```

## Specifying input and output arrays

### Multiple input arrays

The flag `input_arrays` takes in a comma-separated list of input arrays as seen
in the example below. This is useful for models or subgraphs with multiple
inputs.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/inception_v1_2016_08_28_frozen.pb.tar.gz \
  | tar xzv -C /tmp
tflite_convert \
  --graph_def_file=/tmp/inception_v1_2016_08_28_frozen.pb \
  --output_file=/tmp/foo.tflite \
  --input_shapes=1,28,28,96:1,28,28,16:1,28,28,192:1,28,28,64 \
  --input_arrays=InceptionV1/InceptionV1/Mixed_3b/Branch_1/Conv2d_0a_1x1/Relu,InceptionV1/InceptionV1/Mixed_3b/Branch_2/Conv2d_0a_1x1/Relu,InceptionV1/InceptionV1/Mixed_3b/Branch_3/MaxPool_0a_3x3/MaxPool,InceptionV1/InceptionV1/Mixed_3b/Branch_0/Conv2d_0a_1x1/Relu \
  --output_arrays=InceptionV1/Logits/Predictions/Reshape_1
```

Note that `input_shapes` is provided as a colon-separated list. Each input shape
corresponds to the input array at the same position in the respective list.

### Multiple output arrays

The flag `output_arrays` takes in a comma-separated list of output arrays as
seen in the example below. This is useful for models or subgraphs with multiple
outputs.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/inception_v1_2016_08_28_frozen.pb.tar.gz \
  | tar xzv -C /tmp
tflite_convert \
  --graph_def_file=/tmp/inception_v1_2016_08_28_frozen.pb \
  --output_file=/tmp/foo.tflite \
  --input_arrays=input \
  --output_arrays=InceptionV1/InceptionV1/Mixed_3b/Branch_1/Conv2d_0a_1x1/Relu,InceptionV1/InceptionV1/Mixed_3b/Branch_2/Conv2d_0a_1x1/Relu
```

### Specifying subgraphs

Any array in the input file can be specified as an input or output array in
order to extract subgraphs out of an input graph file. TOCO discards the parts
of the graph outside of the specific subgraph. Use [graph
visualizations](#graph-visualizations) to identify the input and output arrays
that make up the desired subgraph.

The follow command shows how to extract a single fused layer out of a TensorFlow
GraphDef.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/inception_v1_2016_08_28_frozen.pb.tar.gz \
  | tar xzv -C /tmp
tflite_convert \
  --graph_def_file=/tmp/inception_v1_2016_08_28_frozen.pb \
  --output_file=/tmp/foo.pb \
  --input_shapes=1,28,28,96:1,28,28,16:1,28,28,192:1,28,28,64 \
  --input_arrays=InceptionV1/InceptionV1/Mixed_3b/Branch_1/Conv2d_0a_1x1/Relu,InceptionV1/InceptionV1/Mixed_3b/Branch_2/Conv2d_0a_1x1/Relu,InceptionV1/InceptionV1/Mixed_3b/Branch_3/MaxPool_0a_3x3/MaxPool,InceptionV1/InceptionV1/Mixed_3b/Branch_0/Conv2d_0a_1x1/Relu \
  --output_arrays=InceptionV1/InceptionV1/Mixed_3b/concat_v2
```

Note that the final representation in TensorFlow Lite FlatBuffers tends to have
coarser granularity than the very fine granularity of the TensorFlow GraphDef
representation. For example, while a fully-connected layer is typically
represented as at least four separate ops in TensorFlow GraphDef (Reshape,
MatMul, BiasAdd, Relu...), it is typically represented as a single "fused" op
(FullyConnected) in the converter's optimized representation and in the final
on-device representation. As the level of granularity gets coarser, some
intermediate arrays (say, the array between the MatMul and the BiasAdd in the
TensorFlow GraphDef) are dropped.

When specifying intermediate arrays as `--input_arrays` and `--output_arrays`,
it is desirable (and often required) to specify arrays that are meant to survive
in the final form of the graph, after fusing. These are typically the outputs of
activation functions (since everything in each layer until the activation
function tends to get fused).

## Logging


## Graph visualizations

TOCO can export a graph to the Graphviz Dot format for easy visualization via
either the `--output_format` flag or the `--dump_graphviz_dir` flag. The
subsections below outline the use cases for each.

### Using `--output_format=GRAPHVIZ_DOT` <a name="using-output-format-graphviz-dot"></a>

The first way to get a Graphviz rendering is to pass `GRAPHVIZ_DOT` into
`--output_format`. This results in a plausible visualization of the graph. This
reduces the requirements that exist during conversion from a TensorFlow GraphDef
to a TensorFlow Lite FlatBuffer. This may be useful if the conversion to TFLite
is failing.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/mobilenet_v1_0.50_128_frozen.tgz \
  | tar xzv -C /tmp
tflite_convert \
  --graph_def_file=/tmp/mobilenet_v1_0.50_128/frozen_graph.pb \
  --output_file=/tmp/foo.dot \
  --output_format=GRAPHVIZ_DOT \
  --input_shape=1,128,128,3 \
  --input_arrays=input \
  --output_arrays=MobilenetV1/Predictions/Reshape_1
```

The resulting `.dot` file can be rendered into a PDF as follows:

```
dot -Tpdf -O /tmp/foo.dot
```

And the resulting `.dot.pdf` can be viewed in any PDF viewer, but we suggest one
with a good ability to pan and zoom across a very large page. Google Chrome does
well in that respect.

```
google-chrome /tmp/foo.dot.pdf
```

Example PDF files are viewable online in the next section.

### Using `--dump_graphviz_dir`

The second way to get a Graphviz rendering is to pass the `--dump_graphviz_dir`
flag, specifying a destination directory to dump Graphviz rendering to. Unlike
the previous approach, this one retains the original output format. This
provides a visualization of the actual graph resulting from a specific
conversion process.

```
curl https://storage.googleapis.com/download.tensorflow.org/models/mobilenet_v1_0.50_128_frozen.tgz \
  | tar xzv -C /tmp
tflite_convert \
  --graph_def_file=/tmp/mobilenet_v1_0.50_128/frozen_graph.pb \
  --output_file=/tmp/foo.tflite \
  --input_arrays=input \
  --output_arrays=MobilenetV1/Predictions/Reshape_1 \
  --dump_graphviz_dir=/tmp
```

This generates a few files in the destination directory. The two most important
files are `toco_AT_IMPORT.dot` and `/tmp/toco_AFTER_TRANSFORMATIONS.dot`.
`toco_AT_IMPORT.dot` represents the original graph containing only the
transformations done at import time. This tends to be a complex visualization
with limited information about each node. It is useful in situations where a
conversion command fails.

`toco_AFTER_TRANSFORMATIONS.dot` represents the graph after all transformations
were applied to it, just before it is exported. Typically, this is a much
smaller graph with more information about each node.

As before, these can be rendered to PDFs:

```
dot -Tpdf -O /tmp/toco_*.dot
```

Sample output files can be seen here:

*   [toco_AT_IMPORT.dot.pdf](https://storage.googleapis.com/download.tensorflow.org/example_images/toco_AT_IMPORT.dot.pdf)
*   [toco_AFTER_TRANSFORMATIONS.dot.pdf](https://storage.googleapis.com/download.tensorflow.org/example_images/toco_AFTER_TRANSFORMATIONS.dot.pdf).

### Graph "video" logging

When `--dump_graphviz_dir` is used, one may additionally pass
`--dump_graphviz_video`. This causes a graph visualization to be dumped after
each individual graph transformation, resulting in thousands of files.
Typically, one would then bisect into these files to understand when a given
change was introduced in the graph.

### Legend for the graph visualizations <a name="graphviz-legend"></a>

*   Operators are red square boxes with the following hues of red:
    *   Most operators are
        <span style="background-color:#db4437;color:white;border:1px;border-style:solid;border-color:black;padding:1px">bright
        red</span>.
    *   Some typically heavy operators (e.g. Conv) are rendered in a
        <span style="background-color:#c53929;color:white;border:1px;border-style:solid;border-color:black;padding:1px">darker
        red</span>.
*   Arrays are octogons with the following colors:
    *   Constant arrays are
        <span style="background-color:#4285f4;color:white;border:1px;border-style:solid;border-color:black;padding:1px">blue</span>.
    *   Activation arrays are gray:
        *   Internal (intermediate) activation arrays are
            <span style="background-color:#f5f5f5;border:1px;border-style:solid;border-color:black;border:1px;border-style:solid;border-color:black;padding:1px">light
            gray</span>.
        *   Those activation arrays that are designated as `--input_arrays` or
            `--output_arrays` are
            <span style="background-color:#9e9e9e;border:1px;border-style:solid;border-color:black;padding:1px">dark
            gray</span>.
    *   RNN state arrays are green. Because of the way that the converter
        represents RNN back-edges explicitly, each RNN state is represented by a
        pair of green arrays:
        *   The activation array that is the source of the RNN back-edge (i.e.
            whose contents are copied into the RNN state array after having been
            computed) is
            <span style="background-color:#b7e1cd;border:1px;border-style:solid;border-color:black;padding:1px">light
            green</span>.
        *   The actual RNN state array is
            <span style="background-color:#0f9d58;color:white;border:1px;border-style:solid;border-color:black;padding:1px">dark
            green</span>. It is the destination of the RNN back-edge updating
            it.
