new algorithm: watermark based on LSB

README.md

@@ -30,6 +30,7 @@ Info Hiding Library
 
 
 
+
 安装
 ```
 pip install HideInfo

example/example_img_watermark.py

@@ -0,0 +1,7 @@
+from hide_info import img_watermark
+
+# 嵌入隐式水印
+img_watermark.file_encode(img_filename="图片.png", watermark_filename="watermark.png", img_filename_new="图片_打入水印.png")
+
+# 提取隐式水印
+img_watermark.file_decode(img_filename="图片_打入水印.png", wm_extract="解出的水印.png")

hide_info/img_watermark.py

@@ -0,0 +1,48 @@
+import numpy
+import numpy as np
+from PIL import Image
+
+
+def encode(img: numpy.ndarray, watermark: numpy.ndarray, n: int):
+    height, width = img.shape[:2]
+    height0, width0 = watermark.shape
+
+    a1 = np.uint8(1 << n)
+    a2 = ~(np.uint8(a1))
+
+    for i in range(height):
+        for j in range(width):
+            if watermark[i % height0, j % width0]:
+                for channel in range(3):
+                    img[i, j, channel] |= a1
+            else:
+                for channel in range(3):
+                    img[i, j, channel] &= a2
+
+
+def decode(img, n):
+    height, width = img.shape[:2]
+    a1 = np.uint8(1 << n)
+    watermark_extract = np.zeros(shape=(height, width), dtype=np.uint8)
+
+    for i in range(height):
+        for j in range(width):
+            tmp = sum(img[i, j, channel] & a1 for channel in range(3))
+            watermark_extract[i, j] = int(tmp * 85)  # 85 = 255 / 3
+
+    return watermark_extract
+
+
+def file_encode(img_filename: str, watermark_filename: str, img_filename_new: str, n: int = 0):
+    # n：0～3，越大水印强度越高
+    watermark = np.array(Image.open(watermark_filename).convert('1'))
+    img = np.array(Image.open(img_filename))
+    encode(img, watermark, n)
+    Image.fromarray(img).save(img_filename_new)
+
+
+def file_decode(img_filename: str, wm_extract: str, n: int = 0):
+    img = np.array(Image.open(img_filename))
+    watermark_extract = decode(img, n)
+    Image.fromarray(watermark_extract).save(wm_extract)
+