python存儲16bit和32bit圖像

筆記：python中存儲16bit和32bit圖像的方法。

說明：主要是利用scipy庫和pillow庫，比較其中的不同。

'''
測試16bit和32bit圖像的python存儲方法
'''
import numpy as np

import scipy.misc
from PIL import Image

# 用已有的8bit和16bit圖作存儲測試
path16 = 'D:\Py_exercise\lena16.tif'
path8  = 'D:\Py_exercise\lena8.tif'
tif16 = scipy.misc.imread(path16)        #<class 'numpy.uint16'>
tif8  = scipy.misc.imread(path8)         #<class 'numpy.uint8'>
print(np.shape(tif16),type(tif16[0,0]))  
print(np.shape(tif8),type(tif8[0,0]))    
print()

save16 = 'D:\Py_exercise\lena16_save.tif'
save8  = 'D:\Py_exercise\lena8_save.tif'
scipy.misc.imsave(save16, tif16)         #--> 8bit
scipy.misc.imsave(save8, tif8)           #--> 8bit


# Create a mat which is 64 bit float
nrows = 512
ncols = 512
np.random.seed(12345)
y = np.random.randn(nrows, ncols)*65535    #<class 'numpy.float64'>
print(type(y[0,0]))
print()

# Convert y to 16 bit unsigned integers
z16 = (y.astype(np.uint16))                #<class 'numpy.uint16'>
print(type(z16[0,0]))
print()

# 用產生的隨機矩陣作存儲測試
save16  = 'D:\Py_exercise\lena16_save1.tif'
scipy.misc.imsave(save16, z16)                 #--> 8bit

im = Image.frombytes('I;16', (ncols,nrows), y.tostring())
im.save('D:\Py_exercise\lena16_save21.tif')    #--> 16bit
im = Image.fromarray(y)                      
im.save('D:\Py_exercise\lena16_save22.tif')    #--> 32bit
im = Image.fromarray(z16)                      
im.save('D:\Py_exercise\lena16_save23.tif')    #--> 16bit

# 歸一化後的np.float64仍然存成了uint8
zNorm = (z16-np.min(z16))/(np.max(z16)-np.min(z16)) #<class 'numpy.float64'>
print(type(zNorm[0,0]))
save16 = 'D:\Py_exercise\lena16_save11.tif'
scipy.misc.imsave(save16, zNorm)               #--> 8bit

# 歸一化後的np.float64直接轉8bit或16bit都會超出閾值,要*255或*65535
# 如果沒有astype的位數設置,會直接存成32bit
zImg = (zNorm*65535).astype(np.uint16) 
im = Image.fromarray(zImg)
im.save('D:\Py_exercise\lena16_save31.tif')    #--> 16bit
im = Image.fromarray(zNorm)
im.save('D:\Py_exercise\lena16_save32.tif')    #--> 32bit(0~1)