Normalize of grayscale camera

AnhTuNguyen

Hello Luxonis team !

I'm currently working with the OAK-D lite and i'm trying to use a neural network on that camera. With this model, I want to use the mono camera (left or right) as input of my neural network.

The input of my model has 3 channels (even with mono camera i want to have 3 channels because my model was trained on both grayscale and rgb images) and has values between -1 and 1, I apply the normalization during the conversion between ONNX to IR format by using --meanvalues [127.5,127.5,127.5] and --scalevalues [127.5,127.5,127.5] as mention in the documentation here .

When I did the test, with mono camera as input (Left/Right), the model just output random values. I tested the same blob on RGB camera and it worked normally. In my case, how can i normalize correctly the image from mono camera ?

Thanks in advance for your support !

jakaskerl

Hi AnhTuNguyen
Could you add an minimal code for the pipeline. Maybe the dimensions are off?

Did you set the type using manip node?:
# The NN model expects BGR input. By default ImageManip output type would be same as input (gray in this case) manip.initialConfig.setFrameType(dai.ImgFrame.Type.BGR888p)

Thanks,
Jaka

AnhTuNguyen

jakaskerl Hello !

Sorry for the delay.
This is my pipeline code

def create_mono(pipeline: dai.Pipeline, socket):
        cam = pipeline.createMonoCamera()
        cam.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
        cam.setBoardSocket(socket)

        # ImageManip for cropping (face detection NN requires input image of 300x300) and to change frame type
        manip = pipeline.create(dai.node.ImageManip)
        manip.initialConfig.setResize(args.HW[1], args.HW[0])
        manip.initialConfig.setFrameType(dai.ImgFrame.Type.BGR888p)
        cam.out.link(manip.inputImage)
        return cam, manip

# setup input cameras
cam_left, processed_left = create_mono(pipeline, dai.CameraBoardSocket.LEFT)
cam_right, processed_right = create_mono(pipeline, dai.CameraBoardSocket.RIGHT)
# create left output node
xout_left = pipeline.createXLinkOut()
xout_left.setStreamName("left")
cam_left.out.link(xout_left.input)
# create right output node
xout_right = pipeline.createXLinkOut()
xout_right.setStreamName("right")
cam_right.out.link(xout_right.input)

# setup neural network node
model = pipeline.create(dai.node.NeuralNetwork)
model.setBlob(args.blob_path)
model.setNumInferenceThreads(2)
processed_left.out.link(model.inputs["frame1"])
processed_right.out.link(model.inputs["frame2"])

jakaskerl

Hi AnhTuNguyen
The code looks fine at first glance. Could you route the image manip directly through Xlink and display its values to see if they are correctly scaled?

Thanks,
Jaka

AnhTuNguyen

jakaskerl

Hello !

I tested it and the values are in good scaled.

I think there is a bug in the manip. I explain the way I test:
- In the output of my model, I also output the input image. The goal is to really see how the input of my model looks like inside the pipeline of depthai. I found very strange input image.

from left to right: Left camera - Right camera - Input frame that my model received.
Knowing that I have a OAK-D Lite, rvc2. depthai version is 2.21.2.0

jakaskerl

Hi AnhTuNguyen
So can you confirm the manip output (sent through xlink) and NN passthrough differ? Maybe draw them both side by side if you can. Also, what is the H, W of the right most image?

Thanks,
Jaka

AnhTuNguyen

jakaskerl

Hi !
That was the figure I sent above: Manip Left - Manip Right - NN input. NN input should be exactly the same as Manip-Left (first image) but somehow it was corrupted into that strange image in my figure.

I tried with Color camera and the right most image was correct --> I only had problem with input come from mono camera - manip.

I used 160x160 for the manip and input of model.

AnhTuNguyen

jakaskerl

Hi !
I found the problem. Since I use mono camera for my neural network, I must specify -ip U8 when I compile the openvino IR to blob. My model works well now.

Thanks a lot for your time !

jakaskerl

Hi AnhTuNguyen
Great! I thought that might be a potential issue, but wouldn't the mismatch on mono cause the

Input tensor 'inputs' (0) exceeds available data range.

error? I figured you probably didn't get that error, otherwise you would have said so - and the error is pretty vocal ;-).

Thanks,
Jaka

AnhTuNguyen

jakaskerl

Hi !
No didnt get that error. If I've had that error, that'd have been much easy to find the cause.