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import random
from typing import Any, Dict
from PIL import Image
import torchvision.transforms as T
import text_recognizer.metadata.iam_lines as metadata
from text_recognizer.data.transforms.image import ImageStem
class LineStem(ImageStem):
"""A stem for handling images containing a line of text."""
def __init__(
self,
augment: bool = False,
color_jitter_kwargs: Dict[str, Any] = None,
random_affine_kwargs: Dict[str, Any] = None,
) -> None:
super().__init__()
if color_jitter_kwargs is None:
color_jitter_kwargs = {"brightness": (0.5, 1)}
if random_affine_kwargs is None:
random_affine_kwargs = {
"degrees": 3,
"translate": (0, 0.05),
"scale": (0.4, 1.1),
"shear": (-40, 50),
"interpolation": T.InterpolationMode.BILINEAR,
"fill": 0,
}
if augment:
self.pil_transforms = T.Compose(
[
T.ColorJitter(**color_jitter_kwargs),
T.RandomAffine(**random_affine_kwargs),
]
)
class IamLinesStem(ImageStem):
"""A stem for handling images containing lines of text from the IAMLines dataset."""
def __init__(
self,
augment: bool = False,
color_jitter_kwargs: Dict[str, Any] = None,
random_affine_kwargs: Dict[str, Any] = None,
) -> None:
super().__init__()
def embed_crop(crop, augment=augment):
# crop is PIL.image of dtype="L" (so values range from 0 -> 255)
image = Image.new("L", (metadata.IMAGE_WIDTH, metadata.IMAGE_HEIGHT))
# Resize crop
crop_width, crop_height = crop.size
new_crop_height = metadata.IMAGE_HEIGHT
new_crop_width = int(new_crop_height * (crop_width / crop_height))
if augment:
# Add random stretching
new_crop_width = int(new_crop_width * random.uniform(0.9, 1.1))
new_crop_width = min(new_crop_width, metadata.IMAGE_WIDTH)
crop_resized = crop.resize(
(new_crop_width, new_crop_height), resample=Image.BILINEAR
)
# Embed in the image
x = min(metadata.CHAR_WIDTH, metadata.IMAGE_WIDTH - new_crop_width)
y = metadata.IMAGE_HEIGHT - new_crop_height
image.paste(crop_resized, (x, y))
return image
if color_jitter_kwargs is None:
color_jitter_kwargs = {"brightness": (0.8, 1.6)}
if random_affine_kwargs is None:
random_affine_kwargs = {
"degrees": 1,
"shear": (-30, 20),
"interpolation": T.InterpolationMode.BILINEAR,
"fill": 0,
}
pil_transform_list = [T.Lambda(embed_crop)]
if augment:
pil_transform_list += [
T.ColorJitter(**color_jitter_kwargs),
T.RandomAffine(**random_affine_kwargs),
]
self.pil_transform = T.Compose(pil_transform_list)
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