license plate accuracy of v1_small

[wang-xinyu]

@YonghaoHe thanks for your work.

I meet a strange problem in license-plate detection, for the same image, when resize it to 320x240, the confidence of the box is 0.99+, but when resize it to 640x480, the confidence only 0.3+. Do you have an idea why this can happen?

regards

[YonghaoHe]

@wang-xinyu if the target license plate is in the range [64, 512], it should be confidently detected. You can resize the image to some other scales, and observe the results. If the problem remains, I guess the failure may be caused by different data distribution. Note that the CCPD dataset is collected in Anhui province.

[wang-xinyu]

@YonghaoHe Thanks a lot.

For the range[64, 512], does it mean the plate width in the image?

For example:

• the original image size is 2048x1536, while plate is around 500x167. Width is 500.
• if resize it to 640x480, the plate is around 160x49. Width is 160.
• if resize to 320x240, the plate is around 80x25. Width is 80.

[YonghaoHe]

@wang-xinyu I means the longer side, in license plate detection, it should always be the width.
In your description, no matter in 640x480 or 320x240, the plate should be well detected. I think the train data matters. You can try some other images to see if the same problem occurs. If you have your own data, you can finetune a new model.

[wang-xinyu]

@YonghaoHe Yes, I understand, thanks a lot!