GCR added

In CMYK we need to use GCR for black channel for 4 channel printers
It optimized based on our requirement

Author: hamed-faraji

halftone.py

@@ -1,102 +1,106 @@
-# %% libraries
 import PIL.Image as Image
 import numpy.matlib
 import numpy as np
 import random
 import math
+import matplotlib.pyplot as plt
+import matplotlib.image as mpimg
 
-# %% functions
-dithMat = [
-    # 8x8 sprial
-    [[62, 58, 45, 41, 37, 49, 53, 61],
-     [54, 34, 25, 21, 17, 29, 33, 57],
-     [50, 30, 13, 9, 5, 12, 24, 44],
-     [38, 18, 6, 1, 0, 8, 20, 40],
-     [42, 22, 10, 2, 3, 4, 16, 36],
-     [46, 26, 14, 7, 11, 15, 28, 48],
-     [59, 35, 31, 19, 23, 27, 32, 52],
-     [63, 55, 51, 39, 43, 47, 56, 60]],
+dithMat =[ 
     # 8x8 dispresed
-    [[1, 30, 8, 28, 2, 29, 7, 27],
-     [17, 9, 24, 16, 18, 10, 23, 15],
-     [5, 25, 3, 32, 6, 26, 4, 31],
-     [21, 13, 19, 11, 22, 14, 20, 12],
-     [2, 29, 7, 27, 1, 30, 8, 28],
-     [18, 10, 23, 15, 17, 9, 24, 16],
-     [6, 26, 4, 31, 5, 25, 3, 32],
-     [22, 14, 20, 12, 21, 13, 19, 11]],
-    # 8X8 octa_dot
-    [[45, 17, 25, 37, 47, 19, 27, 39],
-     [49, 1, 9, 57, 51, 3, 11, 59],
-     [29, 33, 41, 21, 31, 35, 43, 23],
-     [13, 61, 53, 5, 15, 63, 55, 7],
-     [48, 20, 28, 40, 46, 18, 26, 38],
-     [52, 4, 12, 60, 50, 2, 10, 58],
-     [32, 36, 44, 24, 30, 34, 42, 22],
-     [16, 64, 56, 8, 14, 62, 54, 6]],
-    # 5x5 diamond
-    [[5, 118, 160, 58, 17],
-     [48, 201, 232, 170, 99],
-     [129, 211, 252, 242, 150],
-     [89, 191, 221, 181, 68],
-     [38, 78, 140, 108, 27]],
+    [[ 1, 30, 8, 28, 2, 29, 7, 27],
+     [ 17, 9, 24, 16, 18, 10, 23, 15],
+     [ 5, 25, 3, 32, 6, 26, 4, 31],
+     [ 21, 13, 19, 11, 22, 14, 20, 12],
+     [ 2, 29, 7, 27, 1, 30, 8, 28],
+     [ 18, 10, 23, 15, 17, 9, 24, 16],
+     [ 6, 26, 4, 31, 5, 25, 3, 32],
+     [ 22, 14, 20, 12, 21, 13, 19, 11]],
     # 5x5 clockwise sprial
     [[3, 10, 16, 11, 4],
-     [9, 20, 21, 17, 12],
-     [15, 24, 25, 22, 13],
-     [8, 19, 23, 18, 5],
-     [2, 7, 14, 6, 1]],
-    # 4x4 ordered 
-    [[5, 9, 6, 10],
-     [13, 1, 14, 2],
-     [7, 11, 4, 8],
-     [15, 3, 12, 0]],
+     [ 9, 20, 21, 17, 12],
+     [ 15, 24, 25, 22, 13],
+     [ 8, 19, 23, 18, 5],
+     [ 2, 7, 14, 6, 1]],
+    
+    [[0, 8, 2, 10], 
+     [12, 4, 14, 6],
+     [3, 11, 1, 9],
+     [15, 7, 13, 5]],
+    
+    [[0, 32, 8, 40, 2, 34, 10, 42],
+     [48, 16, 56, 24, 50, 18, 58, 26],
+     [3, 35, 11, 43, 1, 33, 9, 41],
+     [51, 19, 59, 27, 49, 17, 57, 25]]
 ]
 
+def gcr(im):
+    cmyk_im = im.convert('CMYK')
+    cmyk_im = cmyk_im.split()
+    cmyk = []
+    check_brightness = []
+    for i in range(4):
+        cmyk.append(np.asarray(cmyk_im[i]))
+        check_brightness.append(np.mean(cmyk[i]) > 128)
+    cmyk = np.asarray(cmyk)
+    check_brightness = np.asarray(check_brightness)
+    if np.mean(check_brightness) > 0.5:
+        percentage = round(random.uniform(0.1,0.5),1)
+    else:
+        percentage = round(random.uniform(0.5,0.9),1)
+        
+    for x in range(im.size[0]):
+        for y in range(im.size[1]):
+            gray = min(cmyk[0][x,y], cmyk[1][x,y], cmyk[2][x,y])* (100/100)
+            for i in range(3):
+                cmyk[i][x,y] = cmyk[i][x,y] - gray
+            cmyk[3][x,y] = gray
+    cmyk_final = []
+    for i in range(4):
+        cmyk_final.append(Image.fromarray(cmyk[i]).convert('L'))
+    return Image.merge('CMYK', cmyk_final)
 
-def get_resDmat(channel_size, dithMat):
-    newSzY, newSzX = channel_size[1], channel_size[0]
+def get_resDmat(channel_size,dithMat):
+    newSzY,newSzX = channel_size[1],channel_size[0]
     minDmat = min(min(dithMat))
     maxDmat = max(max(dithMat))
-    nbOfIntervals = maxDmat - minDmat + 2
-    singleInterval = 255 / nbOfIntervals
-    scaledDithMat = np.multiply(np.subtract(dithMat, minDmat + 1), singleInterval)
+    nbOfIntervals = maxDmat-minDmat+2
+    singleInterval = 255/nbOfIntervals
+    scaledDithMat = np.multiply(np.subtract(dithMat , minDmat+1),singleInterval)
     scaledDithMat = scaledDithMat.astype(int)
 
-    dmatSzY, dmatSzX = len(scaledDithMat), len(scaledDithMat[0])
-    nX = math.ceil(newSzX / dmatSzX)
+
+    dmatSzY, dmatSzX = len(scaledDithMat),len(scaledDithMat[0])
+    nX = math.ceil(newSzX / dmatSzX) 
     nY = math.ceil(newSzY / dmatSzY)
-    resDmat = np.matlib.repmat(scaledDithMat.astype(int), nY, nX)[:newSzY, :newSzX]
+    resDmat = np.matlib.repmat(scaledDithMat.astype(int), nY, nX)[:newSzY,:newSzX]
     return resDmat
 
-
-def generate_halftone(im):
-    cmyk_im = im.convert('CMYK')
-    dithMat_sample = dithMat[random.randint(0, len(dithMat) - 1)]
+def generate_halftone(im,):
+    cmyk_im = gcr(img)
+    dithMat_sample = dithMat[random.randint(0,3)]
     cmyk = cmyk_im.split()
-    angles = [[15, 45, 0, 75],
+    angles = [[75,15,0,45],
               [45, 15, 0, 75],
-              [0, 0, 0, 0]]
-
-    angles = angles[random.randint(0, len(angles) - 1)]
-    if cmyk[0] == cmyk[1] == cmyk[2]:
-        angles = angles[:1] * 4
+              [75,45,0,15]]
+    
+    angles = angles[random.randint(0,2)]
+    if cmyk[0] == cmyk[1] == cmyk[2] :
+        angles = angles[:1]*4
     dots = []
-    for x, i in enumerate(cmyk):
+    for x,i in enumerate(cmyk):
         channel_Rotation = i.rotate(angles[x], expand=1)
-        channel = np.asarray(channel_Rotation) > get_resDmat(channel_Rotation.size, dithMat_sample)
-        channel = Image.fromarray(channel * 255).convert('L').rotate(-angles[x], expand=1)
-        w, h = channel.size
-        im_x, im_y = i.size
-        x1 = (w - im_x) / 2
-        y1 = (h - im_y) / 2
-        channel = channel.crop((x1, y1, x1 + im_x, y1 + im_y))
+        #print(channel_Rotation.size)
+        channel = np.asarray(channel_Rotation) > get_resDmat(channel_Rotation.size,dithMat_sample)
+        channel = Image.fromarray(channel * 255).convert('L').rotate(-angles[x],expand=1)
+        #channel = channel.rotate(-angles[x],expand=1)
+        w,h = channel.size
+        im_x,im_y = i.size
+        x1 = (w-im_x)/2
+        y1 = (h-im_y)/2
+        channel = channel.crop((x1, y1, x1+im_x, y1+im_y))
         dots.append(channel)
-
-    halftoned_im = Image.merge('CMYK', dots)
-    return halftoned_im.convert('RGB')
-
-# %% test
-# im = Image.open('data/Places365_val_00000001.jpg')
-# imh = generate_halftone(im)
-# imh.show()
+    
+    halftoned_im = Image.merge('CMYK',dots)
+    
+    return halftoned_im.convert('RGB')