From a6f6be95125f530a0cf044ec37c59c2970f664fb Mon Sep 17 00:00:00 2001
From: MediaPipe Team <mediapipe-team@google.com>
Date: Fri, 27 Jan 2023 09:20:07 -0800
Subject: [PATCH] Fix incorrect uint8 -> int8 conversion in JS cosine
 similarity.

PiperOrigin-RevId: 505135368
---
 .../tasks/web/components/utils/cosine_similarity.test.ts      | 4 ++--
 mediapipe/tasks/web/components/utils/cosine_similarity.ts     | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mediapipe/tasks/web/components/utils/cosine_similarity.test.ts b/mediapipe/tasks/web/components/utils/cosine_similarity.test.ts
index f442caa20..2a82f388d 100644
--- a/mediapipe/tasks/web/components/utils/cosine_similarity.test.ts
+++ b/mediapipe/tasks/web/components/utils/cosine_similarity.test.ts
@@ -70,12 +70,12 @@ describe('computeCosineSimilarity', () => {
 
   it('succeeds with quantized embeddings', () => {
     const u: Embedding = {
-      quantizedEmbedding: new Uint8Array([255, 128, 128, 128]),
+      quantizedEmbedding: new Uint8Array([127, 0, 0, 0]),
       headIndex: 0,
       headName: ''
     };
     const v: Embedding = {
-      quantizedEmbedding: new Uint8Array([0, 128, 128, 128]),
+      quantizedEmbedding: new Uint8Array([128, 0, 0, 0]),
       headIndex: 0,
       headName: ''
     };
diff --git a/mediapipe/tasks/web/components/utils/cosine_similarity.ts b/mediapipe/tasks/web/components/utils/cosine_similarity.ts
index 1f483b9b6..b512478f4 100644
--- a/mediapipe/tasks/web/components/utils/cosine_similarity.ts
+++ b/mediapipe/tasks/web/components/utils/cosine_similarity.ts
@@ -38,7 +38,7 @@ export function computeCosineSimilarity(u: Embedding, v: Embedding): number {
 }
 
 function convertToBytes(data: Uint8Array): number[] {
-  return Array.from(data, v => v - 128);
+  return Array.from(data, v => v > 127 ? v - 256 : v);
 }
 
 function compute(u: number[], v: number[]) {