A-2 濃度パターンを用いる代表的な濃淡表現「ハーフトーン型ハーフトーニング」
from random import random
img_src = cv2.imread("data/img_A-2.bmp")
img_dst = np.empty_like(img_src)
#座標の大きさ
eight = img_src.shape[0]
width = img_src.shape[1]
patt = np.array([[10,4,6,8],
[12,0,2,14],
[7,9,11,5],
[3,15,13,1]])
for y in range(0,eight,4):
for x in range(0,width,4):
for j in range(4):
for i in range(4):
if img_src[y+j,x+i,0] < patt[i,j] * 16 + 8:
img_dst[y+j,x+i] = [0,0,0]
else:
img_dst[y+j,x+i] = [255,255,255]
#描画する
cv2.imshow("img_src",img_src)
cv2.imshow("img_dst",img_dst)
cv2.waitKey(0)
cv2.destroyAllWindows()
#ヒストグラム
fig = plt.figure()
ax1 = fig.add_subplot(211) #総行数,総列数、サブプロット番号
ax2 = fig.add_subplot(212)
color_list = ["gray"]
ax2.set_ylim(0,5000)
for i,j in enumerate(color_list):
hist = cv2.calcHist([img_src],[i],None,[256],[0,256])
ax1.plot(hist,color = j)
color_list = ["gray"]
ax2.set_ylim(0,5000)
for i,j in enumerate(color_list):
hist = cv2.calcHist([img_dst],[i],None,[256],[0,256])
ax2.plot(hist,color = j)