RGB Value Normalization

[pmiracle]

Hey,

Looking at the image classification application example, I couldn't find any part of the code that handles the normalization of pixel value from [0,255] to [-1,1] or [0,1] that I would expect from a CV model of that kind. 

Do you mind explaining how this implementation that is based on the mobilenet_v2_0 skips the need for normalization?

Thanks.

 

[Julian E.]

Hello @pmiracle,

 

In the example you linked, the deployed model is a model from model zoo: 

mobilenet_v2_0.35_128_fft_int8.tflite

 

This model takes a float32 input [-1,1] and contains the scale and offset:

 

The yaml from model zoo only indicate the scripts how to edit the getting started application for model zoo to deploy it on the stm32. ie:

If you run the deployment yaml throught the stm32ai_main.py, you can look at the edited and deployed application here:  /application_code/image_classification/STM32N6/

 

Have a good day,

Julian

[pmiracle]

Thanks for the reply,

This doesn't makes sense to me, because the camera on the DevKit creates RGB values in the range of 0-255 and there is no code in the example project that I have seen that translates these values to -1,1.

Any explanation?

[Julian E.]

Hello @pmiracle,

 

You're right, I misread. 

The float32[-1:1] is the output (look at the image).

The input is uint8[128,128,3] and most likely RGB values in the range of 0-255 as you pointed out.

 

Have a good day,

Julian