fix_113

aperisolve/analyzers/image_resize.py

@@ -146,6 +146,17 @@ def analyze_image_resize(input_img: Path, output_dir: Path) -> None:
 
         logs.append(f"Target CRC found: 0x{png.crc:08x}")
 
+        if png.crc == png.compute_crc():
+            logs.append(
+                f"PNG is already valid with dimensions {png.width}x{png.height} "
+                f"and crc 0x{png.crc:08x}."
+            )
+            output_data: dict[str, Any] = {
+                "image_resize": {"status": "ok", "output": logs}
+            }
+            update_data(output_dir, output_data)
+            return
+
         saved_img_urls = []
 
         db_matches = lookup_crc(png)

aperisolve/analyzers/utils.py

@@ -180,17 +180,24 @@ class PNG:
         self.height = size[1]
         self.bit_depth = bit_depth
         self.color_type = color_type
-        self.crc = (
+        self.interlace = interlace
-            crc
+        self.crc = crc or self.compute_crc()
-            or zlib.crc32(
+
+    def compute_crc(self) -> int:
+        """Compute the CRC checksum for the PNG IHDR chunk.
+
+        Returns:
+            int: The computed CRC checksum.
+        """
+        return (
+            zlib.crc32(
                 b"IHDR"
                 + self.width.to_bytes(4, "big")
                 + self.height.to_bytes(4, "big")
-                + bytes((bit_depth, color_type, 0, 0, interlace))
+                + bytes((self.bit_depth, self.color_type, 0, 0, self.interlace))
             )
             & 0xFFFFFFFF
         )
-        self.interlace = interlace
 
     @classmethod
     def from_packed(cls, packed: int, crc: int | None = None) -> Self: