fix tests

diylc/diylc-core/src/main/java/org/diylc/presenter/CalcUtils.java

@@ -101,7 +101,9 @@ public class CalcUtils {
       return null;
     }
     double luminance = calculateLuminance(color);
-    Color monochromeColor = (luminance < threshold) ? Color.BLACK : Color.WHITE;
+    // Use <= to handle edge case where luminance equals threshold (should be white)
+    // Add small epsilon to account for floating point precision issues
+    Color monochromeColor = (luminance < threshold - 1e-10) ? Color.BLACK : Color.WHITE;
     // Preserve alpha channel if present
     if (color.getAlpha() < 255) {
       monochromeColor = new Color(monochromeColor.getRed(), monochromeColor.getGreen(), 

diylc/diylc-core/src/test/java/org/diylc/presenter/CalcUtilsTest.java

@@ -229,8 +229,17 @@ public class CalcUtilsTest {
     @Test
     public void testConvertToMonochromeWithAlpha() {
         // Test color with alpha channel - alpha should be preserved
+        // Red (255, 0, 0) has luminance ~76, which is < 128, so it becomes BLACK
         Color transparentRed = new Color(255, 0, 0, 128);
         Color result = CalcUtils.convertToMonochrome(transparentRed);
+        assertEquals(Color.BLACK.getRed(), result.getRed());
+        assertEquals(Color.BLACK.getGreen(), result.getGreen());
+        assertEquals(Color.BLACK.getBlue(), result.getBlue());
+        assertEquals(128, result.getAlpha());
+        
+        // Test light color with alpha - should become WHITE
+        Color transparentLight = new Color(255, 255, 200, 128);
+        result = CalcUtils.convertToMonochrome(transparentLight);
         assertEquals(Color.WHITE.getRed(), result.getRed());
         assertEquals(Color.WHITE.getGreen(), result.getGreen());
         assertEquals(Color.WHITE.getBlue(), result.getBlue());