Fix potential rotation mismatch issue and add webp support for the inactive fast image size checker
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Jaret Burkett committed
1 parent
04733873cf
commit
c22f21fa95
1 file changed
+127
-21
+127
-21
@@ -28,6 +28,69 @@ ICO = types['ICO'] = 'ICO'
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JPEG = types['JPEG'] = 'JPEG'
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PNG = types['PNG'] = 'PNG'
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TIFF = types['TIFF'] = 'TIFF'
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WEBP = types['WEBP'] = 'WEBP'
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# EXIF orientations 5-8 are transposed: the displayed image swaps width/height
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_EXIF_SWAP_ORIENTATIONS = (5, 6, 7, 8)
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# SOF0-15 minus DHT (C4), JPG (C8), DAC (CC)
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_JPEG_SOF_MARKERS = frozenset(range(0xC0, 0xD0)) - {0xC4, 0xC8, 0xCC}
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# markers with no length field: TEM, RST0-7, SOI
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_JPEG_STANDALONE_MARKERS = frozenset(range(0xD0, 0xD8)) | {0x01, 0xD8}
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def _exif_orientation(exif):
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"""Orientation tag (0x0112) from a TIFF-format EXIF blob, or None."""
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if exif.startswith(b"Exif\x00\x00"):
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exif = exif[6:]
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if len(exif) < 8 or exif[:2] not in (b"II", b"MM"):
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return None
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bo = "<" if exif[:2] == b"II" else ">"
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try:
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ifd = struct.unpack(bo + "I", exif[4:8])[0]
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count = struct.unpack(bo + "H", exif[ifd:ifd + 2])[0]
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for i in range(count):
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off = ifd + 2 + i * 12
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tag, typ, n = struct.unpack(bo + "HHI", exif[off:off + 8])
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if tag == 0x0112:
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if typ != 3 or n != 1:
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return None
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return struct.unpack(bo + "H", exif[off + 8:off + 10])[0]
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except struct.error:
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return None
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return None
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def _png_exif_orientation(input):
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"""Walk PNG chunks after IHDR for eXIf; it must precede IDAT, so stop there."""
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pos = 33 # signature + IHDR chunk
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try:
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while True:
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input.seek(pos)
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head = input.read(8)
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if len(head) < 8:
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return None
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length, ctype = struct.unpack(">I4s", head)
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if ctype in (b"IDAT", b"IEND"):
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return None
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if ctype == b"eXIf":
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return _exif_orientation(input.read(length))
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pos += 12 + length
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except struct.error:
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return None
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def _webp_exif_orientation(input, size, pos):
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"""Walk RIFF chunks from pos for EXIF; a few seeks, never the bitstream."""
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try:
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while pos + 8 <= size:
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input.seek(pos)
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fourcc, length = struct.unpack("<4sI", input.read(8))
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if fourcc == b"EXIF":
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return _exif_orientation(input.read(length))
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pos += 8 + length + (length & 1)
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except struct.error:
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return None
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return None
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image_fields = ['path', 'type', 'file_size', 'width', 'height']
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@@ -101,6 +164,9 @@ def get_image_metadata_from_bytesio(input, size, file_path=None):
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Return an `Image` object for a given img file content - no external
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dependencies except the os and struct builtin modules
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Width/height honor the EXIF orientation tag (JPEG APP1, PNG eXIf, WebP
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EXIF chunk), so they match `PIL.ImageOps.exif_transpose(...).size`.
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Args:
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input (io.IOBase): io object support read & seek
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size (int): size of buffer in byte
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@@ -111,7 +177,8 @@ def get_image_metadata_from_bytesio(input, size, file_path=None):
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"""
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height = -1
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width = -1
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data = input.read(26)
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orientation = None
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data = input.read(30)
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msg = " raised while trying to decode as JPEG."
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if (size >= 10) and data[:6] in (b'GIF87a', b'GIF89a'):
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@@ -127,40 +194,75 @@ def get_image_metadata_from_bytesio(input, size, file_path=None):
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w, h = struct.unpack(">LL", data[16:24])
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width = int(w)
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height = int(h)
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elif (size >= 16) and data.startswith(b'\211PNG\r\n\032\n'):
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# older PNGs
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imgtype = PNG
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w, h = struct.unpack(">LL", data[8:16])
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width = int(w)
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height = int(h)
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orientation = _png_exif_orientation(input)
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elif (size >= 2) and data.startswith(b'\377\330'):
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# JPEG
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imgtype = JPEG
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input.seek(0)
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input.read(2)
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b = input.read(1)
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input.seek(2)
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try:
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while (b and ord(b) != 0xDA):
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while (ord(b) != 0xFF):
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b = input.read(1)
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while (ord(b) == 0xFF):
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b = input.read(1)
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if (ord(b) >= 0xC0 and ord(b) <= 0xC3):
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input.read(3)
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while True:
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b = input.read(1)
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if not b:
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raise UnknownImageFormat("no SOF marker" + msg)
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if b != b'\xff':
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continue
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marker = input.read(1)
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while marker == b'\xff': # fill bytes
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marker = input.read(1)
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if not marker:
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raise UnknownImageFormat("no SOF marker" + msg)
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m = ord(marker)
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if m in _JPEG_STANDALONE_MARKERS:
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continue
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if m in (0xD9, 0xDA): # EOI / SOS before any SOF
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raise UnknownImageFormat("no SOF marker" + msg)
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seg_len = struct.unpack(">H", input.read(2))[0] - 2
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if m in _JPEG_SOF_MARKERS:
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input.read(1) # sample precision
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h, w = struct.unpack(">HH", input.read(4))
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break
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if m == 0xE1 and orientation is None:
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# first Exif APP1 wins, same as PIL
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orientation = _exif_orientation(input.read(seg_len))
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else:
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input.read(
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int(struct.unpack(">H", input.read(2))[0]) - 2)
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b = input.read(1)
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input.seek(seg_len, 1)
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width = int(w)
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height = int(h)
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except UnknownImageFormat:
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raise
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except struct.error:
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raise UnknownImageFormat("StructError" + msg)
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except ValueError:
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raise UnknownImageFormat("ValueError" + msg)
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except Exception as e:
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raise UnknownImageFormat(e.__class__.__name__ + msg)
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elif (size >= 30) and data[:4] == b'RIFF' and data[8:12] == b'WEBP':
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# WebP: RIFF header, then first chunk fourcc at 12, chunk size at 16, payload at 20
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imgtype = WEBP
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chunk = data[12:16]
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if chunk == b'VP8 ':
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# lossy: 3-byte frame tag, 3-byte start code, then 14-bit width/height
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if data[23:26] != b'\x9d\x01\x2a':
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raise UnknownImageFormat("bad VP8 start code")
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w, h = struct.unpack("<HH", data[26:30])
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width = int(w & 0x3FFF)
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height = int(h & 0x3FFF)
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elif chunk == b'VP8L':
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# lossless: signature byte, then 14-bit width-1 / height-1 packed LE
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if data[20] != 0x2F:
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raise UnknownImageFormat("bad VP8L signature")
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bits = struct.unpack("<I", data[21:25])[0]
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width = (bits & 0x3FFF) + 1
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height = ((bits >> 14) & 0x3FFF) + 1
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elif chunk == b'VP8X':
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# extended: flags byte, 3 reserved, then 24-bit canvas width-1 / height-1
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width = int.from_bytes(data[24:27], 'little') + 1
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height = int.from_bytes(data[27:30], 'little') + 1
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if data[20] & 0x08: # EXIF flag
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chunk_size = struct.unpack("<I", data[16:20])[0]
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orientation = _webp_exif_orientation(input, size, 20 + chunk_size + (chunk_size & 1))
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else:
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raise UnknownImageFormat("Unknown WebP chunk: " + repr(chunk))
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elif (size >= 26) and data.startswith(b'BM'):
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# BMP
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imgtype = 'BMP'
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@@ -245,7 +347,8 @@ def get_image_metadata_from_bytesio(input, size, file_path=None):
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if 0 != struct.unpack("<H", reserved)[0]:
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raise UnknownImageFormat(FILE_UNKNOWN)
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format = input.read(2)
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assert 1 == struct.unpack("<H", format)[0]
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if 1 != struct.unpack("<H", format)[0]:
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raise UnknownImageFormat(FILE_UNKNOWN)
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num = input.read(2)
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num = struct.unpack("<H", num)[0]
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if num > 1:
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@@ -259,6 +362,9 @@ def get_image_metadata_from_bytesio(input, size, file_path=None):
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else:
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raise UnknownImageFormat(FILE_UNKNOWN)
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if orientation in _EXIF_SWAP_ORIENTATIONS:
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width, height = height, width
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return Image(path=file_path,
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type=imgtype,
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file_size=size,
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