使用 PIL 绘制多语言文本并保存为 1 位和 8 位位图

Question

我从这个不错的答案中的脚本开始。它适用于“RGB”，但 8 位灰度“L”和 1 位黑/白“1”PIL 图像模式只是显示为黑色。我究竟做错了什么？

from PIL import Image, ImageDraw, ImageFont
import numpy as np

w_disp   = 128
h_disp   =  64
fontsize =  32
text     =  u"??!"

for imtype in "1", "L", "RGB":
    image = Image.new(imtype, (w_disp, h_disp))
    draw  = ImageDraw.Draw(image)
    font  = ImageFont.truetype("/Library/Fonts/Arial Unicode.ttf", fontsize)
    w, h  = draw.textsize(text, font=font)
    draw.text(((w_disp - w)/2, (h_disp - h)/2), text, font=font)
    image.save("NiHao! 2 " + imtype + ".bmp")
    data = np.array(list(image.getdata()))
    print data.shape, data.dtype, "min=", data.min(), "max=", data.max()

输出：

(8192,) int64 min= 0 max= 0
(8192,) int64 min= 0 max= 0
(8192, 3) int64 min= 0 max= 255

imtype = "1":

imtype = "L":

imtype = "RGB":

Answer 1

UPDATE:

This answer suggests using PIL's Image.point() method instead of .convert().

The whole thing looks like this:

from PIL import Image, ImageDraw, ImageFont
import numpy as np
w_disp   = 128
h_disp   =  64
fontsize =  32
text     =  u"??!"

imageRGB = Image.new('RGB', (w_disp, h_disp))
draw  = ImageDraw.Draw(imageRGB)
font  = ImageFont.truetype("/Library/Fonts/Arial Unicode.ttf", fontsize)
w, h  = draw.textsize(text, font=font)
draw.text(((w_disp - w)/2, (h_disp - h)/2), text, font=font)

image8bit = imageRGB.convert("L")
imageRGB.save("NiHao! RGB.bmp")
image8bit.save("NiHao! 8bit.bmp")

imagenice_80  = image8bit.point(lambda x: 0 if x < 80  else 1, mode='1')
imagenice_128 = image8bit.point(lambda x: 0 if x < 128 else 1, mode='1')
imagenice_80.save("NiHao! nice 1bit 80.bmp")
imagenice_128.save("NiHao! nice 1bit 128.bmp")

ORIGINAL:

It looks like the TrueType fonts do not want to work with anything less than RGB.

You can try down-converting the images using PIL's .convert() method.

Starting with the RGB image, this gives:

image.convert("L"):

image.convert("1"):

Converting to 8-bit gray scale works nicely, but starting with TrueType fonts, or any font that is based on a gray scale, a 1-bit conversion will always look rough.

For good looking 1-bit images, it is probably necessary to start with a 1-bit bitmapped Chinese font designed for digital on/off displays.