Is there a preferred image channel that Paddle performs better on?

[l03126]

I have noticed that processing the same image on different channels returns different results. I did not test it out with more images but I passed a BGR image and it was recognized correctly. However, the model misclassified the same image when converted to grayscale. So, is there a fixed preferred channel/ config to get better results? (Grayscale/ BGR/ RGB)

Model : Finetuned en_PP-OCRv4_rec

[GreatV]

PaddleOCR generally performs best when the input image is in RGB format, as the models are typically trained and fine-tuned on RGB images. The inconsistency you observed between BGR and grayscale inputs is likely due to the fact that the model's training data and preprocessing pipelines are configured for RGB images.

Here are some key points to address your question:

1. Preferred Image Format:

   • PaddleOCR expects images in the RGB channel format for optimal performance.
   • If you are using OpenCV to preprocess your images, note that OpenCV loads images in BGR format by default. You should convert the image to RGB using cv2.cvtColor(image, cv2.COLOR_BGR2RGB) before passing it to PaddleOCR.

2. Impact of Grayscale Images:

   • Grayscale images reduce the channel dimension from 3 (RGB) to 1, which can significantly disrupt the model’s ability to extract features, especially if the model is trained on color images.
   • This explains why the model misclassified the grayscale version of your image.

3. BGR vs. RGB:

   • While BGR and RGB images contain the same information but with swapped channel orders, feeding BGR images directly to a model trained on RGB data can lead to suboptimal results. Models are sensitive to the order of channels, so always ensure the channel order matches the training setup.

Recommendation:

To ensure the best performance and consistency:

• Always use RGB images as input to PaddleOCR.
• If your image input is in a different format (e.g., BGR or grayscale), convert it to RGB using preprocessing tools like OpenCV.

Additional Reference:

You can refer to the discussion on the official PaddleOCR GitHub repository here, where it's confirmed that PaddleOCR expects images in RGB format.

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