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434b0b0 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 | # Copyright (c) 2023-2024, Zexin He
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -*- coding: utf-8 -*-
# @Organization : Tongyi Lab, Alibaba
# @Author : Lingteng Qiu
# @Email : 220019047@link.cuhk.edu.cn
# @Time : 2025-08-31 10:02:15
# @Function : Image preprocessing with rembg
import numpy as np
import rembg
import cv2
class Preprocessor:
"""
Preprocessing under cv2 conventions.
"""
def __init__(self):
self.rembg_session = rembg.new_session(
providers=["CUDAExecutionProvider", "CPUExecutionProvider"],
)
def preprocess(
self,
image_path: str,
save_path: str,
rmbg: bool = True,
recenter: bool = True,
size: int = 512,
border_ratio: float = 0.2,
):
image = self.step_load_to_size(image_path=image_path, size=size * 2)
if rmbg:
image = self.step_rembg(image_in=image)
else:
image = cv2.cvtColor(image, cv2.COLOR_BGR2BGRA)
if recenter:
image = self.step_recenter(
image_in=image, border_ratio=border_ratio, square_size=size
)
else:
image = cv2.resize(
src=image,
dsize=(size, size),
interpolation=cv2.INTER_AREA,
)
return cv2.imwrite(save_path, image)
def step_rembg(self, image_in: np.ndarray) -> np.ndarray:
image_out = rembg.remove(
data=image_in,
session=self.rembg_session,
)
return image_out
def step_recenter(
self, image_in: np.ndarray, border_ratio: float, square_size: int
) -> np.ndarray:
assert image_in.shape[-1] == 4, "Image to recenter must be RGBA"
mask = image_in[..., -1] > 0
ijs = np.nonzero(mask)
# find bbox
i_min, i_max = ijs[0].min(), ijs[0].max()
j_min, j_max = ijs[1].min(), ijs[1].max()
bbox_height, bbox_width = i_max - i_min, j_max - j_min
# recenter and resize
desired_size = int(square_size * (1 - border_ratio))
scale = desired_size / max(bbox_height, bbox_width)
desired_height, desired_width = int(bbox_height * scale), int(
bbox_width * scale
)
desired_i_min, desired_j_min = (square_size - desired_height) // 2, (
square_size - desired_width
) // 2
desired_i_max, desired_j_max = (
desired_i_min + desired_height,
desired_j_min + desired_width,
)
# create new image
image_out = np.zeros((square_size, square_size, 4), dtype=np.uint8)
image_out[desired_i_min:desired_i_max, desired_j_min:desired_j_max] = (
cv2.resize(
src=image_in[i_min:i_max, j_min:j_max],
dsize=(desired_width, desired_height),
interpolation=cv2.INTER_AREA,
)
)
return image_out
def step_load_to_size(self, image_path: str, size: int) -> np.ndarray:
image = cv2.imread(image_path, cv2.IMREAD_UNCHANGED)
height, width = image.shape[:2]
scale = size / max(height, width)
height, width = int(height * scale), int(width * scale)
image_out = cv2.resize(
src=image,
dsize=(width, height),
interpolation=cv2.INTER_AREA,
)
return image_out
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