fix calculation alpha with mask opacity

projects/coloration/src/lib/coloration.ts

@@ -134,7 +134,7 @@ export class Coloration {
             const B = baseColor.intColor & 0x0000FF;
 
             if (additionalColor.alpha) {
-                this.calcColor.alpha = this.minmax(baseColor.alpha + additionalColor.alpha, 0, 1);
+                this.calcColor.alpha = this.minmax(baseColor.alpha + additionalColor.alpha * opacity, 0, 1);
             }
             this.calcColor.intColor = this.rgbToInt(
                 Math.round(((additionalColor.intColor >> 16) - R) * lum) + R,