ColorJitter in PyTorch

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ColorJitter() can change the brightness, contrast, saturation and hue of an image as shown below:

*Memos:

• The 1st argument for initialization is brightness(Optional-Default:0-Type:int, float or tuple/list(int or float)): *Memos:
  • It's the range of the brightness [min, max] so it must be min <= max.
  • It must be 0 <= x.
  • A tuple/list must be the 1D with 2 elements.
  • A single value means [max(0, 1-brightness), 1+brightness].
• The 2nd argument for initialization is contrast(Optional-Default:0-Type:int, float or tuple/list(int or float)): *Memos:
  • It's the range of the contrast [min, max] so it must be min <= max.
  • It must be 0 <= x.
  • A tuple/list must be the 1D with 2 elements.
  • A single value means [max(0, 1-contrast), 1+contrast].
• The 3rd argument for initialization is saturation(Optional-Default:0-Type:int, float or tuple/list(int or float)): *Memos:
  • It's the range of the saturation [min, max] so it must be min <= max.
  • It must be 0 <= x.
  • A tuple/list must be the 1D with 2 elements.
  • A single value means [max(0, 1-saturation), 1+saturation].
• The 4th argument for initialization is hue(Optional-Default:0-Type:float or tuple/list(float)): *Memos:
  • It's the range of the hue [min, max] so it must be min <= max.
  • It must be -0.5 <= x <= 0.5.
  • A tuple or list must be the 1D with 2 elements.
  • A single value means [-hue, +hue].
• The 1st argument is img(Required-Type:PIL Image or tensor(int)): *Memos:
  • A tensor must be 2D or 3D.
  • Don't use img=.
• v2 is recommended to use according to V1 or V2? Which one should I use?.

from torchvision.datasets import OxfordIIITPet
from torchvision.transforms.v2 import ColorJitter

colorjitter = ColorJitter()
colorjitter = ColorJitter(brightness=0,
                          contrast=0,
                          saturation=0,
                          hue=0)
colorjitter = transform=ColorJitter(brightness=[1, 1]),
                                    contrast=[1, 1],
                                    saturation=[1, 1],
                                    hue=[0, 0])
colorjitter
# ColorJitter()

print(colorjitter.brightness)
# None

print(colorjitter.contrast)
# None

print(colorjitter.saturation)
# None

print(colorjitter.hue)
# None

origin_data = OxfordIIITPet(
    root="data",
    transform=None
    # transform=ColorJitter()
    # colorjitter = ColorJitter(brightness=0,
    #                           contrast=0,
    #                           saturation=0,
    #                           hue=0)
    # transform=ColorJitter(brightness=[1, 1]),
    #                       contrast=[1, 1],
    #                       saturation=[1, 1],
    #                       hue=[0, 0])
)

brightp2_data = OxfordIIITPet( # `bright` is brightness and `p` is plus.
    root="data",
    transform=ColorJitter(brightness=2)
    # transform=ColorJitter(brightness=[0, 3])
)

brightp2p2_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(brightness=[2, 2])
)

brightp05p05_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(brightness=[0.5, 0.5])
)

contrap2_data = OxfordIIITPet( # `contra` is contrast.
    root="data",
    transform=ColorJitter(contrast=2)
    # transform=ColorJitter(contrast=[0, 3])
)

contrap2p2_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(contrast=[2, 2])
)

contrap05p05_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(contrast=[0.5, 0.5])
)

saturap2_data = OxfordIIITPet( # `satura` is saturation.
    root="data",
    transform=ColorJitter(saturation=2)
    # transform=ColorJitter(saturation=[0, 3])
)

saturap2p2_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(saturation=[2, 2])
)

saturap05p05_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(saturation=[0.5, 0.5])
)

huep05_data = OxfordIIITPet(
    root="data",
    transform=ColorJitter(hue=0.5)
    # transform=ColorJitter(hue=[-0.5, 0.5])
)

huep025p025_data = OxfordIIITPet( # `m` is minus.
    root="data",
    transform=ColorJitter(hue=[0.25, 0.25])
)

huem025m025_data = OxfordIIITPet( # `m` is minus.
    root="data",
    transform=ColorJitter(hue=[-0.25, -0.25])
)

import matplotlib.pyplot as plt

def show_images1(data, main_title=None):
    plt.figure(figsize=(10, 5))
    plt.suptitle(t=main_title, y=0.8, fontsize=14)
    for i, (im, _) in zip(range(1, 6), data):
        plt.subplot(1, 5, i)
        plt.imshow(X=im)
        plt.xticks(ticks=[])
        plt.yticks(ticks=[])
    plt.tight_layout()
    plt.show()

show_images1(data=origin_data, main_title="origin_data")
show_images1(data=brightp2_data, main_title="brightp2_data")
show_images1(data=brightp2p2_data, main_title="brightp2p2_data")
show_images1(data=brightp05p05_data, main_title="brightp05p05_data")
print()
show_images1(data=origin_data, main_title="origin_data")
show_images1(data=contrap2_data, main_title="contrap2_data")
show_images1(data=contrap2p2_data, main_title="contrap2p2_data")
show_images1(data=contrap05p05_data, main_title="contrap05p05_data")
print()
show_images1(data=origin_data, main_title="origin_data")
show_images1(data=saturap2_data, main_title="saturap2_data")
show_images1(data=saturap2p2_data, main_title="saturap2p2_data")
show_images1(data=saturap05p05_data, main_title="saturap05p05_data")
print()
show_images1(data=origin_data, main_title="origin_data")
show_images1(data=huep05_data, main_title="huep05_data")
show_images1(data=huep025p025_data, main_title="huep025p025_data")
show_images1(data=huem025m025_data, main_title="huem025m025_data")

# ↓ ↓ ↓ ↓ ↓ ↓ The code below is identical to the code above. ↓ ↓ ↓ ↓ ↓ ↓
def show_images2(data, main_title=None, b=0, c=0, s=0, h=0):
    plt.figure(figsize=(10, 5))
    plt.suptitle(t=main_title, y=0.8, fontsize=14)
    for i, (im, _) in zip(range(1, 6), data):
        plt.subplot(1, 5, i)
        cj = ColorJitter(brightness=b, contrast=c, # Here
                         saturation=s, hue=h)
        plt.imshow(X=cj(im)) # Here
        plt.xticks(ticks=[])
        plt.yticks(ticks=[])
    plt.tight_layout()
    plt.show()

show_images2(data=my_data, main_title="origin_data")
show_images2(data=my_data, main_title="brightp2_data", b=2)
show_images2(data=my_data, main_title="brightp2p2_data", b=[2, 2])
show_images2(data=my_data, main_title="brightp05p05_data", b=[0.5, 0.5])
print()
show_images2(data=my_data, main_title="origin_data")
show_images2(data=my_data, main_title="contrap2_data", c=2)
show_images2(data=my_data, main_title="contrap2p2_data", c=[2, 2])
show_images2(data=my_data, main_title="contrap05p05_data", c=[0.5, 0.5])
print()
show_images2(data=my_data, main_title="origin_data")
show_images2(data=my_data, main_title="saturap2_data", s=2)
show_images2(data=my_data, main_title="saturap2p2_data", s=[2, 2])
show_images2(data=my_data, main_title="saturap05p05_data", s=[0.5, 0.5])
print()
show_images2(data=my_data, main_title="origin_data")
show_images2(data=my_data, main_title="huep05_data", h=0.5)
show_images2(data=my_data, main_title="huep025p025_data", h=[0.25, 0.25])
show_images2(data=my_data, main_title="huem025m025_data", h=[-0.25, -0.25])

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