如何在Python中将8bpp位图转换为1bpp位图

Question

我有一些代码，这是很好的创建灰度(8bpp)图像，但我需要创建1bpp(二进制)也为打印机。我在这里看到了2个帖子，但不明白他们是如何解决这个问题的。在PIL中不能将BMP图像数据格式化为每像素1位我已经安装了pillow，但是我把它称为使用PIL，因为我读过的所有教程似乎都说要从PIL导入图像。

我有一个叫做conv_to_1bpp的方法，它将255设置为1，但这仍然是8bpp的图像。

from PIL import Image
import numpy as np
import os
import sys
import struct

class BmpMaker:
def __init__(self):
self.ffp = None
self.img_width = None
self.img_height = None
self.ws_activation = None
self.bpp = None
def make_image(self, img_width, img_height, ws_activation):
"""Creates a bitmap."""
self.ffp = None
self.img_width = img_width
self.img_height = img_height
self.ws_activation = ws_activation

# Create new black image - L mode for b/w
img = Image.new('L', (img_width, img_height))
# Convert to Numpy array for easy processing
na = np.array(img)
# set the amount of white space activation
white_rows = ws_activation
# make white lines
na[0:white_rows, 0:999] = 255
# Revert to PIL Image from Numpy array and save
self.ffp = self.make_img_title(img_width, img_height, ws_activation)
Image.fromarray(na).save(self.ffp)
self.bpp = self.get_bitdepth()
return self.ffp
def make_img_title(self, img_width, img_height, ws_activation):
if ws_activation == 0:
mystr = f"{img_height}x{img_width}"
elif ws_activation is not None:
mystr = f"{ws_activation}_{img_height}x{img_width}"
self.ffp = os.path.join(os.getcwd(), mystr + ".bmp")
print("img_ffp : ", self.ffp)
return self.ffp
def get_bitdepth(self):
# Read first 100 bytes
with open(self.ffp, 'rb') as f:
BMP = f.read(100)
if BMP[0:2] != b'BM':
sys.exit('ERROR: Incorrect BMP signature')
# Get BITMAPINFOHEADER size - https://en.wikipedia.org/wiki/BMP_file_format
BITMAPINFOHEADERSIZE = struct.unpack('<i', BMP[14:18])[0]
okSizes = [40, 52, 56, 108, 124]
if BITMAPINFOHEADERSIZE not in okSizes:
sys.exit(f'ERROR: BITMAPINFOHEADER size was {BITMAPINFOHEADERSIZE},'
f' expected one of {okSizes}')
# Get bits per pixel
self.bpp = struct.unpack('<H', BMP[28:30])[0]
print(f'bbp: {self.bpp}')
return self.bpp
def get_img_bitdepth(self, img):
# Read first 100 bytes
with open(img, 'rb') as f:
BMP = f.read(100)
if BMP[0:2] != b'BM':
sys.exit('ERROR: Incorrect BMP signature')
# Get BITMAPINFOHEADER size - https://en.wikipedia.org/wiki/BMP_file_format
BITMAPINFOHEADERSIZE = struct.unpack('<i', BMP[14:18])[0]
okSizes = [40, 52, 56, 108, 124]
if BITMAPINFOHEADERSIZE not in okSizes:
sys.exit(f'ERROR: BITMAPINFOHEADER size was {BITMAPINFOHEADERSIZE},'
f' expected one of {okSizes}')
# Get bits per pixel
img_bpp = struct.unpack('<H', BMP[28:30])[0]
print(f'bbp: {img_bpp}')
return img_bpp
def conv_to_1bpp(self):
img = Image.open(self.ffp)
arr = np.array(img)
#print(arr)
# Set all values at indices where the array equals 255 to 1.
arr[arr==255] = 1
print('n'*3, arr)
Image.fromarray(arr).save("my_img.bmp")
print(self.get_img_bitdepth("my_img.bmp"))

if __name__ == "__main__":
import PIL
print('Pillow Version:', PIL.__version__)
bm = BmpMaker()
base_image = bm.make_image(1000, 8, 5)
print("bitmap ffp: ", bm.ffp)
print("bitmap bitdepth : ", bm.bpp)
bm.conv_to_1bpp()

Answer 1

创建初始图像时使用模式'1'代替'L'

# Create new black image - L mode for b/w, '1' for binary
img = Image.new('1', (img_width, img_height))