CODEWITHSUNDEEP
androidandroid-jetpack-composegoogle-mlkitroitext-recognition
Hocine Elhadj
Hocine Elhadj

Reputation: 105

How to Use Region of Interest (ROI) for ML Kit Text Recognition with Camera Preview in Android?

I'm working on an Android application using Jetpack Compose and the ML Kit Text Recognition API. I want to implement a Region of Interest (ROI) so that the text recognition only processes images within this specific area of the camera preview. Here are the details:

Setup: Camera Library: Using CameraX for camera preview. Text Recognition: Using ML Kit for text recognition. UI Framework: Jetpack Compose. Problem: Currently, the text recognition processes the entire camera preview, but I want it to focus on a specific rectangular area defined by an ROI. I've created the ROI as a Rect in my Composable function, but I'm not sure how to ensure that the text recognition only analyzes the portion of the image that corresponds to this rectangle.

Code Snippet: Here's the relevant part of my code where I set up the TextRecognitionAnalyzer:

class TextRecognitionAnalyzer(
    private val mrzRect: Rect,
    private val screenSize: IntSize,
    private val onTextDetected: (Text) -> Unit
) : ImageAnalysis.Analyzer {
    // Analyzer implementation...
}

I’m currently using the following approach to determine the crop area for text recognition based on the mrzRect:

val cropLeft = // calculate crop left based on ROI and scaling
val cropTop = // calculate crop top based on ROI and scaling
val cropRight = // calculate crop right based on ROI and scaling
val cropBottom = // calculate crop bottom based on ROI and scaling

// Use the cropped area for text recognition...

Questions:

1 - How do I accurately calculate the coordinates for cropping the image based on the ROI?

2 - What adjustments do I need to make to ensure that the text recognition operates solely within the defined ROI?

3 - Are there any best practices or common pitfalls to avoid when working with ROI and camera previews in this context?

Additional Information:

I'm facing issues where the readings are not accurately confined to the ROI. The text recognition sometimes picks up text outside of this area.

Upvotes: 1

Views: 97

Answers (0)

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