234 lines
8.4 KiB
Python
234 lines
8.4 KiB
Python
#
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# The Python Imaging Library.
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#
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# QOI support for PIL
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#
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# See the README file for information on usage and redistribution.
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#
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from __future__ import annotations
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import os
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from typing import IO
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from . import Image, ImageFile
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from ._binary import i32be as i32
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from ._binary import o8
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from ._binary import o32be as o32
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def _accept(prefix: bytes) -> bool:
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return prefix.startswith(b"qoif")
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class QoiImageFile(ImageFile.ImageFile):
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format = "QOI"
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format_description = "Quite OK Image"
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def _open(self) -> None:
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if not _accept(self.fp.read(4)):
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msg = "not a QOI file"
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raise SyntaxError(msg)
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self._size = i32(self.fp.read(4)), i32(self.fp.read(4))
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channels = self.fp.read(1)[0]
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self._mode = "RGB" if channels == 3 else "RGBA"
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self.fp.seek(1, os.SEEK_CUR) # colorspace
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self.tile = [ImageFile._Tile("qoi", (0, 0) + self._size, self.fp.tell())]
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class QoiDecoder(ImageFile.PyDecoder):
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_pulls_fd = True
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_previous_pixel: bytes | bytearray | None = None
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_previously_seen_pixels: dict[int, bytes | bytearray] = {}
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def _add_to_previous_pixels(self, value: bytes | bytearray) -> None:
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self._previous_pixel = value
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r, g, b, a = value
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hash_value = (r * 3 + g * 5 + b * 7 + a * 11) % 64
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self._previously_seen_pixels[hash_value] = value
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def decode(self, buffer: bytes | Image.SupportsArrayInterface) -> tuple[int, int]:
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assert self.fd is not None
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self._previously_seen_pixels = {}
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self._previous_pixel = bytearray((0, 0, 0, 255))
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data = bytearray()
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bands = Image.getmodebands(self.mode)
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dest_length = self.state.xsize * self.state.ysize * bands
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while len(data) < dest_length:
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byte = self.fd.read(1)[0]
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value: bytes | bytearray
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if byte == 0b11111110 and self._previous_pixel: # QOI_OP_RGB
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value = bytearray(self.fd.read(3)) + self._previous_pixel[3:]
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elif byte == 0b11111111: # QOI_OP_RGBA
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value = self.fd.read(4)
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else:
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op = byte >> 6
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if op == 0: # QOI_OP_INDEX
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op_index = byte & 0b00111111
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value = self._previously_seen_pixels.get(
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op_index, bytearray((0, 0, 0, 0))
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)
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elif op == 1 and self._previous_pixel: # QOI_OP_DIFF
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value = bytearray(
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(
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(self._previous_pixel[0] + ((byte & 0b00110000) >> 4) - 2)
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% 256,
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(self._previous_pixel[1] + ((byte & 0b00001100) >> 2) - 2)
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% 256,
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(self._previous_pixel[2] + (byte & 0b00000011) - 2) % 256,
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self._previous_pixel[3],
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)
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)
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elif op == 2 and self._previous_pixel: # QOI_OP_LUMA
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second_byte = self.fd.read(1)[0]
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diff_green = (byte & 0b00111111) - 32
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diff_red = ((second_byte & 0b11110000) >> 4) - 8
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diff_blue = (second_byte & 0b00001111) - 8
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value = bytearray(
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tuple(
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(self._previous_pixel[i] + diff_green + diff) % 256
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for i, diff in enumerate((diff_red, 0, diff_blue))
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)
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)
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value += self._previous_pixel[3:]
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elif op == 3 and self._previous_pixel: # QOI_OP_RUN
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run_length = (byte & 0b00111111) + 1
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value = self._previous_pixel
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if bands == 3:
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value = value[:3]
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data += value * run_length
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continue
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self._add_to_previous_pixels(value)
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if bands == 3:
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value = value[:3]
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data += value
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self.set_as_raw(data)
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return -1, 0
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def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
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if im.mode == "RGB":
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channels = 3
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elif im.mode == "RGBA":
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channels = 4
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else:
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msg = "Unsupported QOI image mode"
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raise ValueError(msg)
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colorspace = 0 if im.encoderinfo.get("colorspace") == "sRGB" else 1
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fp.write(b"qoif")
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fp.write(o32(im.size[0]))
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fp.write(o32(im.size[1]))
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fp.write(o8(channels))
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fp.write(o8(colorspace))
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ImageFile._save(im, fp, [ImageFile._Tile("qoi", (0, 0) + im.size)])
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class QoiEncoder(ImageFile.PyEncoder):
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_pushes_fd = True
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_previous_pixel: tuple[int, int, int, int] | None = None
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_previously_seen_pixels: dict[int, tuple[int, int, int, int]] = {}
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_run = 0
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def _write_run(self) -> bytes:
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data = o8(0b11000000 | (self._run - 1)) # QOI_OP_RUN
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self._run = 0
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return data
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def _delta(self, left: int, right: int) -> int:
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result = (left - right) & 255
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if result >= 128:
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result -= 256
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return result
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def encode(self, bufsize: int) -> tuple[int, int, bytes]:
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assert self.im is not None
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self._previously_seen_pixels = {0: (0, 0, 0, 0)}
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self._previous_pixel = (0, 0, 0, 255)
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data = bytearray()
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w, h = self.im.size
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bands = Image.getmodebands(self.mode)
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for y in range(h):
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for x in range(w):
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pixel = self.im.getpixel((x, y))
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if bands == 3:
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pixel = (*pixel, 255)
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if pixel == self._previous_pixel:
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self._run += 1
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if self._run == 62:
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data += self._write_run()
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else:
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if self._run:
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data += self._write_run()
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r, g, b, a = pixel
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hash_value = (r * 3 + g * 5 + b * 7 + a * 11) % 64
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if self._previously_seen_pixels.get(hash_value) == pixel:
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data += o8(hash_value) # QOI_OP_INDEX
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elif self._previous_pixel:
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self._previously_seen_pixels[hash_value] = pixel
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prev_r, prev_g, prev_b, prev_a = self._previous_pixel
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if prev_a == a:
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delta_r = self._delta(r, prev_r)
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delta_g = self._delta(g, prev_g)
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delta_b = self._delta(b, prev_b)
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if (
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-2 <= delta_r < 2
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and -2 <= delta_g < 2
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and -2 <= delta_b < 2
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):
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data += o8(
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0b01000000
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| (delta_r + 2) << 4
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| (delta_g + 2) << 2
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| (delta_b + 2)
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) # QOI_OP_DIFF
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else:
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delta_gr = self._delta(delta_r, delta_g)
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delta_gb = self._delta(delta_b, delta_g)
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if (
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-8 <= delta_gr < 8
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and -32 <= delta_g < 32
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and -8 <= delta_gb < 8
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):
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data += o8(
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0b10000000 | (delta_g + 32)
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) # QOI_OP_LUMA
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data += o8((delta_gr + 8) << 4 | (delta_gb + 8))
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else:
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data += o8(0b11111110) # QOI_OP_RGB
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data += bytes(pixel[:3])
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else:
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data += o8(0b11111111) # QOI_OP_RGBA
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data += bytes(pixel)
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self._previous_pixel = pixel
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if self._run:
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data += self._write_run()
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data += bytes((0, 0, 0, 0, 0, 0, 0, 1)) # padding
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return len(data), 0, data
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Image.register_open(QoiImageFile.format, QoiImageFile, _accept)
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Image.register_decoder("qoi", QoiDecoder)
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Image.register_extension(QoiImageFile.format, ".qoi")
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Image.register_save(QoiImageFile.format, _save)
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Image.register_encoder("qoi", QoiEncoder)
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