Python PIL 字节转图像

Question

import PIL
from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont
import urllib.request

with urllib.request.urlopen('http://pastebin.ca/raw/2311595') as in_file:
    hex_data = in_file.read()
print(hex_data)
img = Image.frombuffer('RGB', (320,240), hex_data) #i have tried fromstring
draw = ImageDraw.Draw(img)
font = ImageFont.truetype("arial.ttf",14)
draw.text((0, 220),"This is a test11",(255,255,0),font=font)
draw = ImageDraw.Draw(img)
img.save("a_test.jpg")

我正在尝试把二进制数据转换成图片，然后再在上面画文字。但是我遇到了一个错误，错误信息是：

img = Image.frombuffer('RGB', (320,240), hex_data) 
raise ValueError("not enough image data")
ValueError: not enough image data

我在这里上传了字节字符串 http://pastebin.ca/raw/2311595
而且我可以确定图片的大小是320x240

补充说明

我可以确认这个图片的字节字符串是来自320x240的，只要运行代码就能从字节字符串创建出一张图片

import urllib.request
import binascii
import struct

# Download the data.
with urllib.request.urlopen('http://pastebin.ca/raw/2311595') as in_file:
     hex_data = in_file.read()
# Unhexlify the data.
bin_data = binascii.unhexlify(hex_data)
print(bin_data)
# Remove the embedded lengths.
jpeg_data = bin_data
# Write out the JPEG.
with open('out.jpg', 'wb') as out_file:
    out_file.write(jpeg_data)

问题解决了，这是更新后的代码

from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont
import urllib.request
import io
import binascii

data = urllib.request.urlopen('http://pastebin.ca/raw/2311595').read()
r_data = binascii.unhexlify(data)
#r_data = "".unhexlify(chr(int(b_data[i:i+2],16)) for i in range(0, len(b_data),2))

stream = io.BytesIO(r_data)

img = Image.open(stream)
draw = ImageDraw.Draw(img)
font = ImageFont.truetype("arial.ttf",14)
draw.text((0, 220),"This is a test11",(255,255,0),font=font)
draw = ImageDraw.Draw(img)
img.save("a_test.png")

Answer 1

就像其他人说的，Python 3 更好用 io.BytesIO。

import io
from PIL import Image

imageFileObj = open(imageFilename, "rb")
imageBinaryBytes = imageFileObj.read()
imageStream = io.BytesIO(imageBinaryBytes)
imageFile = Image.open(imageStream)
print("imageFile.size=%s" % imageFile.size)

Answer 2

那张图片不是由原始字节组成的，而是一个经过编码的JPEG文件。此外，你并没有把流中的ascii HEX表示解析成正确的字节：也就是说，文件中的“ff”序列被当作两个字符“f”传给了PIL，而不是一个值为255的字节。

所以，首先，你需要把字符串解码成正确的字节序列——抱歉说得有点复杂——可能有更简单的方法，但我今天状态不太好：

data = urllib.urlopen("http://pastebin.ca/raw/2311595").read()
r_data = "".join(chr(int(data[i:i+2],16)) for i in range(0, len(data),2)) 

哦，C.Y.在评论中提到了一种方法：

>>> import binascii
>>> b_data = binascii.unhexlify(data)

现在，你可以把它作为JPEG图片导入到PIL中：

>>> from PIL import Image
>>> import cStringIO as StringIO
>>> stream = StringIO.StringIO(b_data)
>>> img = Image.open(stream)
>>> img.size
(320, 240)