如何使用Python将RGB565字节数组转换为RGB888字节数组？

Question

根据我对RGB888 to RGB565的问题，我想做RGB565到RGB888，这是我的测试代码，但是我在转换到RGB888字节数组时遇到了困难

import numpy as np
np.random.seed(42)
im = np.random.randint(0,256,(1,4,2), dtype=np.uint8)

# >>> im.nbytes
# 8
# >>> im
# array([[[102, 220],
#        [225,  95],
#        [179,  61],
#        [234, 203]]], dtype=uint8)

# Make components of RGB888
R8 = (im[...,0] & 0xF8).astype(np.uint32) << 8
G8 = (im[...,0] & 0x07).astype(np.uint32) << 5 | (im[...,1] & 0xE0).astype(np.uint32)
B8 = (im[...,1] & 0x1F).astype(np.uint32)
RGB888 = R8 | G8 | B8

# >>> RGB888.nbytes
# 16 <= here I think it should be 12 (4x3 bytes)

# >>> RGB888.reshape(1, 4, 3)
# Traceback (most recent call last):
#   File "<input>", line 1, in <module>
# ValueError: cannot reshape array of size 4 into shape (1,4,3)

当我使用astype（np.uint16）时，一些值变为0，因为它需要更大的数据类型来存储，这就是我在上述代码中使用unit32的原因

我知道unit32将使上述代码的RGB888大小为16，所以我想问一下，是否有其他正确的方式将RGB565传输到RGB888

Answer 1

类似这样的内容可以将您从RGB565uint16转换为三个uint8通道阵列，然后您可以将它们dstack转换为单个三维RGB图像：

import numpy as np
np.random.seed(42)
im = np.random.randint(0,65536,(4,4), dtype=np.uint16)

MASK5 = 0b011111
MASK6 = 0b111111

# TODO: BGR or RGB? Who knows!
b = (im & MASK5) << 3
g = ((im >> 5) & MASK6) << 2
r = ((im >> (5 + 6)) & MASK5) << 3

# Compose into one 3-dimensional matrix of 8-bit integers
rgb = np.dstack((r,g,b)).astype(np.uint8)

编辑：要将uint8s的W x H x 2数组转换为uint16s的W x H数组

import numpy as np
np.random.seed(42)
im = np.random.randint(0,256,(4,4,2), dtype=np.uint8)

b1 = im[:,:,0].astype(np.uint16)
b2 = im[:,:,1].astype(np.uint16)
im = (b1 << 8 | b2)

您可能需要根据源阵列的端向性交换b1和b2