screen: update tresholds on text

screen.go

@@ -67,63 +67,77 @@ func (d *Device) GetScreenResolution() (int, int, error) {
 	return d.Screenx, d.Screeny, nil
 }
 
-// Get the text on screen in a certain area using gotesseract
 func (d *Device) GetScreenText(xStart int, xEnd int, yStart int, yEnd int, whitelist string, multiline bool) (string, error) {
-	// Take screenshot in memory and get bytes
-	data, err := d.RunCommand("exec-out screencap -p")
-	if err != nil {
-		return "", fmt.Errorf("failed to take screenshot: %w", err)
-	}
+    data, err := d.RunCommand("exec-out screencap -p")
+    if err != nil {
+        return "", fmt.Errorf("failed to take screenshot: %w", err)
+    }
 
-	// Decode image from bytes
-	img, err := png.Decode(bytes.NewReader(data))
-	if err != nil {
-		return "", fmt.Errorf("failed to decode PNG: %w", err)
-	}
+    img, err := png.Decode(bytes.NewReader(data))
+    if err != nil {
+        return "", fmt.Errorf("failed to decode PNG: %w", err)
+    }
 
-	// Crop region
-	rect := image.Rect(0, 0, xEnd-xStart, yEnd-yStart)
-	cropped := image.NewRGBA(rect)
-	for y := yStart; y < yEnd; y++ {
-		for x := xStart; x < xEnd; x++ {
-			cropped.Set(x-xStart, y-yStart, img.At(x, y))
-		}
-	}
+    rect := image.Rect(0, 0, xEnd-xStart, yEnd-yStart)
+    cropped := image.NewRGBA(rect)
+    for y := yStart; y < yEnd; y++ {
+        for x := xStart; x < xEnd; x++ {
+            cropped.Set(x-xStart, y-yStart, img.At(x, y))
+        }
+    }
 
-	// Convert to grayscale and apply threshold
-	threshold := uint8(160)
-	binarized := image.NewGray(rect)
-	for y := 0; y < rect.Dy(); y++ {
-		for x := 0; x < rect.Dx(); x++ {
-			gray := color.GrayModel.Convert(cropped.At(x, y)).(color.Gray)
-			if gray.Y > threshold {
-				binarized.SetGray(x, y, color.Gray{Y: 255})
-			} else {
-				binarized.SetGray(x, y, color.Gray{Y: 0})
-			}
-		}
-	}
+    // Convert to grayscale
+    gray := image.NewGray(rect)
+    for y := 0; y < rect.Dy(); y++ {
+        for x := 0; x < rect.Dx(); x++ {
+            gray.Set(x, y, color.GrayModel.Convert(cropped.At(x, y)))
+        }
+    }
 
-	// Encode binarized image to PNG
-	var buf bytes.Buffer
-	if err := png.Encode(&buf, binarized); err != nil {
-		return "", fmt.Errorf("failed to encode image: %w", err)
-	}
+    // Apply simple mean-based adaptive thresholding
+    binarized := image.NewGray(rect)
+    window := 15 // size of local region
+    for y := 0; y < rect.Dy(); y++ {
+        for x := 0; x < rect.Dx(); x++ {
+            var sum int
+            var count int
+            for dy := -window / 2; dy <= window/2; dy++ {
+                for dx := -window / 2; dx <= window/2; dx++ {
+                    xx := x + dx
+                    yy := y + dy
+                    if xx >= 0 && xx < rect.Dx() && yy >= 0 && yy < rect.Dy() {
+                        sum += int(gray.GrayAt(xx, yy).Y)
+                        count++
+                    }
+                }
+            }
+            mean := sum / count
+            if int(gray.GrayAt(x, y).Y) < mean-10 {
+                binarized.SetGray(x, y, color.Gray{Y: 0})
+            } else {
+                binarized.SetGray(x, y, color.Gray{Y: 255})
+            }
+        }
+    }
 
-	// Call tesseract
-	client := gosseract.NewClient()
-	defer client.Close()
-	client.SetImageFromBytes(buf.Bytes())
-	client.SetWhitelist(whitelist)
-	if multiline {
-		client.SetPageSegMode(gosseract.PSM_AUTO)
-	} else {
-		client.SetPageSegMode(gosseract.PSM_SINGLE_BLOCK)
-	}
+    var buf bytes.Buffer
+    if err := png.Encode(&buf, binarized); err != nil {
+        return "", fmt.Errorf("failed to encode image: %w", err)
+    }
 
-	text, err := client.Text()
-	if err != nil {
-		return "", fmt.Errorf("tesseract error: %w", err)
-	}
-	return text, nil
+    client := gosseract.NewClient()
+    defer client.Close()
+    client.SetImageFromBytes(buf.Bytes())
+    client.SetWhitelist(whitelist)
+    if multiline {
+        client.SetPageSegMode(gosseract.PSM_AUTO)
+    } else {
+        client.SetPageSegMode(gosseract.PSM_SINGLE_BLOCK)
+    }
+
+    text, err := client.Text()
+    if err != nil {
+        return "", fmt.Errorf("tesseract error: %w", err)
+    }
+    return text, nil
 }