fix(vewport): Add missing blendmodes from cornerstonejs (#4055)

extensions/cornerstone/src/utils/getCornerstoneBlendMode.ts

@@ -1,6 +1,8 @@
 import { Enums } from '@cornerstonejs/core';
 
 const MIP = 'mip';
+const MINIP = 'minip';
+const AVG = 'avg';
 
 export default function getCornerstoneBlendMode(blendMode: string): Enums.BlendModes {
   if (!blendMode) {
@@ -11,5 +13,13 @@ export default function getCornerstoneBlendMode(blendMode: string): Enums.BlendM
     return Enums.BlendModes.MAXIMUM_INTENSITY_BLEND;
   }
 
-  throw new Error();
+  if (blendMode.toLowerCase() === MINIP) {
+    return Enums.BlendModes.MINIMUM_INTENSITY_BLEND;
+  }
+
+  if (blendMode.toLowerCase() === AVG) {
+    return Enums.BlendModes.AVERAGE_INTENSITY_BLEND;
+  }
+
+  throw new Error(`Unsupported blend mode: ${blendMode}`);
 }