hsc.py

#!/usr/bin/python
import numpy as np

class HSC:
    'Hue Saturation Control'

    def __init__(self, img, hue, saturation, clip):
        self.img = img
        self.hue = hue
        self.saturation = saturation
        self.clip = clip

    def clipping(self):
        np.clip(self.img, 0, self.clip, out=self.img)
        return self.img

    def lut(self):
        ind = np.array([i for i in range(360)])
        sin = np.sin(ind * np.pi / 180) * 256
        cos = np.cos(ind * np.pi / 180) * 256
        lut_sin = dict(zip(ind, [round(sin[i]) for i in ind]))
        lut_cos = dict(zip(ind, [round(cos[i]) for i in ind]))
        return lut_sin, lut_cos

    def execute(self):
        lut_sin, lut_cos = self.lut()
        img_h = self.img.shape[0]
        img_w = self.img.shape[1]
        img_c = self.img.shape[2]
        hsc_img = np.empty((img_h, img_w, img_c), np.int16)
        hsc_img[:,:,0] = (self.img[:,:,0] - 128) * lut_cos[self.hue] + (self.img[:,:,1] - 128) * lut_sin[self.hue] + 128
        hsc_img[:,:,1] = (self.img[:,:,1] - 128) * lut_cos[self.hue] - (self.img[:,:,0] - 128) * lut_sin[self.hue] + 128
        hsc_img[:,:,0] = self.saturation * (self.img[:,:,0] - 128) / 256 + 128
        hsc_img[:,:,1] = self.saturation * (self.img[:,:,1] - 128) / 256 + 128
        self.img = hsc_img
        return self.clipping()