# Casting NN subtraction

This example demonstrates how to perform frame subtraction using a
[NeuralNetwork](https://docs.luxonis.com/software/depthai-components/nodes/neural_network.md) and the
[Cast](https://docs.luxonis.com/software/depthai-components/nodes/cast_node.md) node.

## Demo

## Setup

Please run the [install script](https://github.com/luxonis/depthai-python/blob/main/examples/install_requirements.py) to download
all required dependencies. Please note that this script must be ran from git context, so you have to download the
[depthai-python](https://github.com/luxonis/depthai-python) repository first and then run the script

```bash
git clone https://github.com/luxonis/depthai-python.git
cd depthai-python/examples
python3 install_requirements.py
```

For additional information, please follow the [installation guide](https://docs.luxonis.com/software/depthai/manual-install.md).

## Source code

#### Python

```python
#!/usr/bin/env python3

import cv2
import depthai as dai
from pathlib import Path

SHAPE = 720

p = dai.Pipeline()

camRgb = p.create(dai.node.ColorCamera)
nn = p.create(dai.node.NeuralNetwork)
script = p.create(dai.node.Script)
rgbXout = p.create(dai.node.XLinkOut)
cast = p.create(dai.node.Cast)
castXout = p.create(dai.node.XLinkOut)

camRgb.setVideoSize(SHAPE, SHAPE)
camRgb.setPreviewSize(SHAPE, SHAPE)
camRgb.setInterleaved(False)

nnBlobPath = (Path(__file__).parent / Path('../models/diff_openvino_2022.1_6shave.blob')).resolve().absolute()
nn.setBlobPath(nnBlobPath)

script.setScript("""
old = node.io['in'].get()
while True:
    frame = node.io['in'].get()
    node.io['img1'].send(old)
    node.io['img2'].send(frame)
    old = frame
""")

rgbXout.setStreamName("rgb")
castXout.setStreamName("cast")
cast.setOutputFrameType(dai.RawImgFrame.Type.GRAY8)

# Linking
camRgb.preview.link(script.inputs['in'])
script.outputs['img1'].link(nn.inputs['img1'])
script.outputs['img2'].link(nn.inputs['img2'])
camRgb.video.link(rgbXout.input)
nn.out.link(cast.input)
cast.output.link(castXout.input)

# Pipeline is defined, now we can connect to the device
with dai.Device(p) as device:
    qCam = device.getOutputQueue(name="rgb", maxSize=4, blocking=False)
    qCast = device.getOutputQueue(name="cast", maxSize=4, blocking=False)

    while True:
        colorFrame = qCam.get()
        assert isinstance(colorFrame, dai.ImgFrame)
        cv2.imshow("Color", colorFrame.getCvFrame())

        inCast = qCast.get()
        assert isinstance(inCast, dai.ImgFrame)
        cv2.imshow("Diff", inCast.getCvFrame())

        if cv2.waitKey(1) == ord('q'):
            break
```

#### C++

```cpp
#include <depthai/depthai.hpp>
#include <filesystem>
#include <opencv2/opencv.hpp>

constexpr int SHAPE = 720;

int main() {
    dai::Pipeline p;

    auto camRgb = p.create<dai::node::ColorCamera>();
    auto nn = p.create<dai::node::NeuralNetwork>();
    auto script = p.create<dai::node::Script>();
    auto rgbXout = p.create<dai::node::XLinkOut>();
    auto cast = p.create<dai::node::Cast>();
    auto castXout = p.create<dai::node::XLinkOut>();

    camRgb->setVideoSize(SHAPE, SHAPE);
    camRgb->setPreviewSize(SHAPE, SHAPE);
    camRgb->setInterleaved(false);

    nn->setBlobPath(BLOB_PATH);

    script->setScript(R"(
        old = node.io['in'].get()
        while True:
            frame = node.io['in'].get()
            node.io['img1'].send(old)
            node.io['img2'].send(frame)
            old = frame
    )");

    rgbXout->setStreamName("rgb");
    castXout->setStreamName("cast");
    cast->setOutputFrameType(dai::RawImgFrame::Type::GRAY8);

    // Linking
    camRgb->preview.link(script->inputs["in"]);
    script->outputs["img1"].link(nn->inputs["img1"]);
    script->outputs["img2"].link(nn->inputs["img2"]);
    camRgb->video.link(rgbXout->input);
    nn->out.link(cast->input);
    cast->output.link(castXout->input);

    // Pipeline is defined, now we can connect to the device
    dai::Device device(p);
    auto qCam = device.getOutputQueue("rgb", 4, false);
    auto qCast = device.getOutputQueue("cast", 4, false);

    while(true) {
        auto colorFrame = qCam->get<dai::ImgFrame>();
        if(colorFrame) {
            cv::imshow("Color", colorFrame->getCvFrame());
        }

        auto inCast = qCast->get<dai::ImgFrame>();
        if(inCast) {
            cv::imshow("Diff", inCast->getCvFrame());
        }

        if(cv::waitKey(1) == 'q') {
            break;
        }
    }

    return 0;
}
```

## Pipeline

### examples/cast_diff.pipeline.json

```json
{
  "pipeline": {
    "connections": [
      {
        "node1Id": 0,
        "node1Output": "preview",
        "node1OutputGroup": "",
        "node2Id": 2,
        "node2Input": "in",
        "node2InputGroup": "io"
      },
      {
        "node1Id": 2,
        "node1Output": "img1",
        "node1OutputGroup": "io",
        "node2Id": 1,
        "node2Input": "img1",
        "node2InputGroup": "inputs"
      },
      {
        "node1Id": 2,
        "node1Output": "img2",
        "node1OutputGroup": "io",
        "node2Id": 1,
        "node2Input": "img2",
        "node2InputGroup": "inputs"
      },
      {
        "node1Id": 0,
        "node1Output": "video",
        "node1OutputGroup": "",
        "node2Id": 3,
        "node2Input": "in",
        "node2InputGroup": ""
      },
      {
        "node1Id": 1,
        "node1Output": "out",
        "node1OutputGroup": "",
        "node2Id": 4,
        "node2Input": "input",
        "node2InputGroup": ""
      },
      {
        "node1Id": 4,
        "node1Output": "output",
        "node1OutputGroup": "",
        "node2Id": 5,
        "node2Input": "in",
        "node2InputGroup": ""
      }
    ],
    "globalProperties": {
      "calibData": null,
      "cameraTuningBlobSize": null,
      "cameraTuningBlobUri": "",
      "leonCssFrequencyHz": 700000000.0,
      "leonMssFrequencyHz": 700000000.0,
      "pipelineName": null,
      "pipelineVersion": null,
      "sippBufferSize": 18432,
      "sippDmaBufferSize": 16384,
      "xlinkChunkSize": -1
    },
    "nodes": [
      [
        0,
        {
          "id": 0,
          "ioInfo": [
            [
              [
                "",
                "inputConfig"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 1,
                "name": "inputConfig",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "raw"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 6,
                "name": "raw",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "still"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 7,
                "name": "still",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "inputControl"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 2,
                "name": "inputControl",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "video"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 3,
                "name": "video",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "isp"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 4,
                "name": "isp",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "preview"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 5,
                "name": "preview",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "frameEvent"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 8,
                "name": "frameEvent",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "ColorCamera",
          "properties": {
            "boardSocket": -1,
            "cameraName": "",
            "colorOrder": 0,
            "fp16": false,
            "fps": 30.0,
            "imageOrientation": -1,
            "initialControl": {
              "aeLockMode": false,
              "aeMaxExposureTimeUs": 0,
              "aeRegion": {
                "height": 0,
                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "afRegion": {
                "height": 0,
                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "antiBandingMode": 0,
              "autoFocusMode": 3,
              "awbLockMode": false,
              "awbMode": 0,
              "brightness": 0,
              "captureIntent": 0,
              "chromaDenoise": 0,
              "cmdMask": 0,
              "contrast": 0,
              "controlMode": 0,
              "effectMode": 0,
              "expCompensation": 0,
              "expManual": {
                "exposureTimeUs": 0,
                "frameDurationUs": 0,
                "sensitivityIso": 0
              },
              "frameSyncMode": 0,
              "lensPosAutoInfinity": 0,
              "lensPosAutoMacro": 0,
              "lensPosition": 0,
              "lensPositionRaw": 0.0,
              "lowPowerNumFramesBurst": 0,
              "lowPowerNumFramesDiscard": 0,
              "lumaDenoise": 0,
              "saturation": 0,
              "sceneMode": 0,
              "sharpness": 0,
              "strobeConfig": {
                "activeLevel": 0,
                "enable": 0,
                "gpioNumber": 0
              },
              "strobeTimings": {
                "durationUs": 0,
                "exposureBeginOffsetUs": 0,
                "exposureEndOffsetUs": 0
              },
              "wbColorTemp": 0
            },
            "interleaved": false,
            "isp3aFps": 0,
            "ispScale": {
              "horizDenominator": 0,
              "horizNumerator": 0,
              "vertDenominator": 0,
              "vertNumerator": 0
            },
            "numFramesPoolIsp": 3,
            "numFramesPoolPreview": 4,
            "numFramesPoolRaw": 3,
            "numFramesPoolStill": 4,
            "numFramesPoolVideo": 4,
            "previewHeight": 720,
            "previewKeepAspectRatio": true,
            "previewWidth": 720,
            "rawPacked": null,
            "resolution": 0,
            "sensorCropX": -1.0,
            "sensorCropY": -1.0,
            "stillHeight": -1,
            "stillWidth": -1,
            "videoHeight": 720,
            "videoWidth": 720
          }
        }
      ],
      [
        1,
        {
          "id": 1,
          "ioInfo": [
            [
              [
                "",
                "in"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 9,
                "name": "in",
                "queueSize": 5,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "inputs",
                "img1"
              ],
              {
                "blocking": false,
                "group": "inputs",
                "id": 10,
                "name": "img1",
                "queueSize": 1,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "inputs",
                "img2"
              ],
              {
                "blocking": false,
                "group": "inputs",
                "id": 11,
                "name": "img2",
                "queueSize": 1,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "",
                "out"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 12,
                "name": "out",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "passthrough"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 13,
                "name": "passthrough",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "NeuralNetwork",
          "properties": {
            "blobSize": 2010,
            "blobUri": "asset:__blob",
            "numFrames": 8,
            "numNCEPerThread": 0,
            "numThreads": 0
          }
        }
      ],
      [
        2,
        {
          "id": 2,
          "ioInfo": [
            [
              [
                "io",
                "in"
              ],
              {
                "blocking": true,
                "group": "io",
                "id": 14,
                "name": "in",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "io",
                "img1"
              ],
              {
                "blocking": false,
                "group": "io",
                "id": 15,
                "name": "img1",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "io",
                "img2"
              ],
              {
                "blocking": false,
                "group": "io",
                "id": 16,
                "name": "img2",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "Script",
          "properties": {
            "processor": 1,
            "scriptName": "<script>",
            "scriptUri": "asset:__script"
          }
        }
      ],
      [
        3,
        {
          "id": 3,
          "ioInfo": [
            [
              [
                "",
                "in"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 17,
                "name": "in",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": true
              }
            ]
          ],
          "name": "XLinkOut",
          "properties": {
            "maxFpsLimit": -1.0,
            "metadataOnly": false,
            "streamName": "rgb"
          }
        }
      ],
      [
        4,
        {
          "id": 4,
          "ioInfo": [
            [
              [
                "",
                "input"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 18,
                "name": "input",
                "queueSize": 4,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "",
                "output"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 19,
                "name": "output",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "passthroughInput"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 20,
                "name": "passthroughInput",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "Cast",
          "properties": {
            "numFramesPool": 4,
            "offset": null,
            "outputType": 30,
            "scale": null
          }
        }
      ],
      [
        5,
        {
          "id": 5,
          "ioInfo": [
            [
              [
                "",
                "in"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 21,
                "name": "in",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": true
              }
            ]
          ],
          "name": "XLinkOut",
          "properties": {
            "maxFpsLimit": -1.0,
            "metadataOnly": false,
            "streamName": "cast"
          }
        }
      ]
    ]
  }
}
```

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