def color_space_transform()

in src/util/flip_loss.py [0:0]

• 96 lines of code
• 18 McCabe index (conditional complexity)

def color_space_transform(input_color, fromSpace2toSpace):
    dim = input_color.size()

    if fromSpace2toSpace == "srgb2linrgb":
        input_color = torch.clamp(input_color, 0.0, 1.0)  # clamp added to stabilize training
        limit = 0.04045
        transformed_color = torch.where(input_color > limit, torch.pow((input_color + 0.055) / 1.055, 2.4), input_color / 12.92)

    elif fromSpace2toSpace == "linrgb2srgb":
        input_color = torch.clamp(input_color, 0.0, 1.0)  # clamp added to stabilize training
        limit = 0.0031308
        transformed_color = torch.where(input_color > limit, 1.055 * (input_color ** (1.0 / 2.4)) - 0.055, 12.92 * input_color)

    elif fromSpace2toSpace == "linrgb2xyz" or fromSpace2toSpace == "xyz2linrgb":
        # Source: https://www.image-engineering.de/library/technotes/958-how-to-convert-between-srgb-and-ciexyz
        # Assumes D65 standard illuminant
        a11 = 10135552 / 24577794
        a12 = 8788810 / 24577794
        a13 = 4435075 / 24577794
        a21 = 2613072 / 12288897
        a22 = 8788810 / 12288897
        a23 = 887015 / 12288897
        a31 = 1425312 / 73733382
        a32 = 8788810 / 73733382
        a33 = 70074185 / 73733382
        A = torch.Tensor([[a11, a12, a13],
                          [a21, a22, a23],
                          [a31, a32, a33]])

        input_color = input_color.view(dim[0], dim[1], dim[2] * dim[3]).cuda()  # NC(HW)
        if fromSpace2toSpace == "xyz2linrgb":
            A = torch.inverse(A)
        transformed_color = torch.matmul(A.cuda(), input_color)
        transformed_color = transformed_color.view(dim[0], dim[1], dim[2], dim[3])

    elif fromSpace2toSpace == "xyz2ycxcz":
        reference_illuminant = color_space_transform(torch.ones(dim), 'linrgb2xyz')
        input_color = torch.div(input_color, reference_illuminant)
        y = 116 * input_color[:, 1:2, :, :] - 16
        cx = 500 * (input_color[:, 0:1, :, :] - input_color[:, 1:2, :, :])
        cz = 200 * (input_color[:, 1:2, :, :] - input_color[:, 2:3, :, :])
        transformed_color = torch.cat((y, cx, cz), 1)

    elif fromSpace2toSpace == "ycxcz2xyz":
        y = (input_color[:, 0:1, :, :] + 16) / 116
        cx = input_color[:, 1:2, :, :] / 500
        cz = input_color[:, 2:3, :, :] / 200

        x = y + cx
        z = y - cz
        transformed_color = torch.cat((x, y, z), 1)

        reference_illuminant = color_space_transform(torch.ones(dim), 'linrgb2xyz')
        transformed_color = torch.mul(transformed_color, reference_illuminant)

    elif fromSpace2toSpace == "xyz2lab":
        reference_illuminant = color_space_transform(torch.ones(dim), 'linrgb2xyz')
        input_color = torch.div(input_color, reference_illuminant)
        delta = 6 / 29
        limit = 0.00885

        input_color = torch.where(input_color > limit, torch.pow(input_color, 1 / 3), (input_color / (3 * delta * delta)) + (4 / 29))

        l = 116 * input_color[:, 1:2, :, :] - 16
        a = 500 * (input_color[:, 0:1, :, :] - input_color[:, 1:2, :, :])
        b = 200 * (input_color[:, 1:2, :, :] - input_color[:, 2:3, :, :])

        transformed_color = torch.cat((l, a, b), 1)

    elif fromSpace2toSpace == "lab2xyz":
        y = (input_color[:, 0:1, :, :] + 16) / 116
        a = input_color[:, 1:2, :, :] / 500
        b = input_color[:, 2:3, :, :] / 200

        x = y + a
        z = y - b

        xyz = torch.cat((x, y, z), 1)
        delta = 6 / 29
        xyz = torch.where(xyz > delta, xyz ** 3, 3 * delta ** 2 * (xyz - 4 / 29))

        reference_illuminant = color_space_transform(torch.ones(dim), 'linrgb2xyz')
        transformed_color = torch.mul(xyz, reference_illuminant)

    elif fromSpace2toSpace == "srgb2xyz":
        transformed_color = color_space_transform(input_color, 'srgb2linrgb')
        transformed_color = color_space_transform(transformed_color, 'linrgb2xyz')
    elif fromSpace2toSpace == "srgb2ycxcz":
        transformed_color = color_space_transform(input_color, 'srgb2linrgb')
        transformed_color = color_space_transform(transformed_color, 'linrgb2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2ycxcz')
    elif fromSpace2toSpace == "linrgb2ycxcz":
        transformed_color = color_space_transform(input_color, 'linrgb2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2ycxcz')
    elif fromSpace2toSpace == "srgb2lab":
        transformed_color = color_space_transform(input_color, 'srgb2linrgb')
        transformed_color = color_space_transform(transformed_color, 'linrgb2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2lab')
    elif fromSpace2toSpace == "linrgb2lab":
        transformed_color = color_space_transform(input_color, 'linrgb2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2lab')
    elif fromSpace2toSpace == "ycxcz2linrgb":
        transformed_color = color_space_transform(input_color, 'ycxcz2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2linrgb')
    elif fromSpace2toSpace == "lab2srgb":
        transformed_color = color_space_transform(input_color, 'lab2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2linrgb')
        transformed_color = color_space_transform(transformed_color, 'linrgb2srgb')
    elif fromSpace2toSpace == "ycxcz2lab":
        transformed_color = color_space_transform(input_color, 'ycxcz2xyz')
        transformed_color = color_space_transform(transformed_color, 'xyz2lab')
    else:
        print('The color transform is not defined!')
        transformed_color = input_color

    return transformed_color