illuminants: Add D65 variant calculated from CIE 1nm SPD data
diff --git a/src/commonMain/kotlin/dev/kdrag0n/colorkt/data/Illuminants.kt b/src/commonMain/kotlin/dev/kdrag0n/colorkt/data/Illuminants.kt
index 503618e..170ec61 100644
--- a/src/commonMain/kotlin/dev/kdrag0n/colorkt/data/Illuminants.kt
+++ b/src/commonMain/kotlin/dev/kdrag0n/colorkt/data/Illuminants.kt
@@ -34,6 +34,20 @@
     )
 
     /**
+     * CIE Standard Illuminant D65. ~6500K color temperature; approximates average daylight in Europe.
+     * This uses XYZ values calculated from raw 1nm SPD data from the CIE, combined with the CIE 1931 2-degree
+     * standard observer.
+     *
+     * @see <a href="https://www.rit.edu/cos/colorscience/rc_useful_data.php">RIT - Useful Color Data</a>
+     */
+    @JvmField
+    public val D65_CIE: CieXyz = CieXyz(
+        x = 0.9504705586542832,
+        y = 1.0,
+        z = 1.088828736395884,
+    )
+
+    /**
      * CIE Standard Illuminant D50. ~5000K color temperature.
      */
     @JvmField