# Pre-processing

Pre-processing (or image processing) prepares the captured screen image before it's sent to the OCR engine for text recognition.

**Important:** Pre-processing is primarily useful for **traditional OCR engines** (Tesseract OCR and Windows OCR). If you're using **modern OCR engines** like Fast OCR or **AI-based engines** (Google Cloud Vision, Azure Cloud Vision, LLM-based engines), you can skip pre-processing as these engines handle various image conditions automatically.

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#### **When to Use Pre-processing**

Use pre-processing when:

* You're using **Tesseract OCR** or **Windows OCR**
* Game text has colored or complex backgrounds
* There's low contrast between text and background
* OCR accuracy is poor without adjustments

Skip pre-processing when:

* You're using **Fast OCR**, **EasyOCR**, or other modern engines
* You're using **AI-based engines** (Qwen 2.5 VL, GPT-4 Vision, Claude Vision)
* You're using **cloud-based engines** (Google Cloud Vision, Azure Cloud Vision)

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### Pre-processing Options

#### **Image Upscaler** (OCR Master)

Increases the resolution or size of the captured image. Higher resolution can help the OCR engine recognize small or blurry text more accurately.

#### **Image Filter** (OCR Master)

Removes background colors and enhances text visibility. There are three filter options:

* **Black Text Filter**
  * Converts the image to show black text on a white background
* **White Text Filter**
  * Converts the image to show white text on a black background
* **Color Text Filter**
  * Preserves text colors while removing background

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#### Image Adjustments

Fine-tune the captured image for better text recognition:

* **Greyscale**&#x20;
  * Converts the image to black and white (removes all colors)
* **Normalize**
  * Automatically adjusts image brightness and contrast
  * Adjust the threshold value to make text stand out more clearly
* **Invert**
  * Swaps black and white colors in the image
* **Threshold**
  * Controls the contrast between text and background
  * Adjust the threshold value to make text stand out more clearly
* **Lightness**
  * Adjusts the overall lightness of the image
* **Brightness**
  * Adjusts how bright or dark the image appears
* **Sharpen**
  * Makes text edges more defined and clear