# How to configure OpenCV launcher¶

For enabling OpenCV launcher you need to add framework: opencv in launchers section of your configuration file and provide following parameters:

• device - specifies which device will be used for infer (cpu, gpu, gpu_fp16 etc.).

• tags - optional specifies which device bit type will be used for infer (FP32 and FP16).

• backend - specifies which backend OpenCV’s will be used for infer (ocv and ie).

• model/weights - path to configuration files with model and weights for your topology (prototxt/caffemodel, xml/bin, pbtxt/pb etc.) and preferably used in pairs .

• adapter - approach how raw output will be converted to representation of dataset problem, some adapters can be specific to framework. You can find detailed instruction how to use adapters here.

You also should specify all inputs for your model with their shapes to write inputs, using specific parameter: inputs. Each input description should has following info:

• name - input layer name in network

• type - type of input values, it has impact on filling policy. Available options:

• CONST_INPUT - input will be filled using constant provided in config. It also requires to provide value.

• IMAGE_INFO - specific key for setting information about input shape to layer (used in Faster RCNN based topologies). You do not need to provide value, because it will be calculated in runtime. Format value is list with N elements of the form [H, W, S], where N is batch size, H - original image height, W - original image width, S - scale of original image (default 1).

• ORIG_IMAGE_INFO - specific key for setting information about original image size before preprocessing.

• PROCESSED_IMAGE_INFO - specific key for setting information about input size after preprocessing.

• SCALE_FACTOR - specific key for setting information about image scale factor defined as [SCALE_Y, SCALE_X], where SCALE_Y = <resized_image_height>/<original_image_height, SCALE_X = <resized_image_width> / <original_image_width>

• IGNORE_INPUT - input which should be stayed empty during evaluation.

• INPUT - network input for main data stream (e. g. images). If you have several data inputs, you should provide regular expression for identifier as value for specifying which one data should be provided in specific input.

• shape - shape of input layer described as comma-separated of all dimensions size except batch size.

Optionally you can determine layout in case when your model was trained with non-standard data layout (For OpenCV default layout is NCHW) and precision (Supported precisions: FP32 - float, FP16 - signed shot, U8 - unsigned char, U16 - unsigned short int, I8 - signed char, I16 - short int, I32 - int, I64 - long int).

OpenCV launcher config example:

launchers:
- framework: opencv
device: CPU
backend: OCV
model: path_to_model/alexnet.prototxt
weights: path_to_weights/alexnet.caffemodel
inputs:
- name: 'input'
type: INPUT
shape: 3, 32, 32
adapter: classification