python - Python Pil Change GreyScale Tif To RGB

Question

I have a greyscale TIF File. I need to convert it to RGB/ read from it in a way I can work with it.

img = Image.open(GIF_FILENAME)
rgbimg = img.convert('RGB')
for i in range(5):
    print rgbimg.getpixel((i, 0))

The convert.("RGB") will automatically make everything (255,255,255) even though the picture is a really dark mostly black picture.

If I just read the greyscale numbers I get numbers from around 1400 to 1900.

I need to also save a copy of the picture as a RGB Jpeg. Picture in question: [Here]: http://imgur.com/kEwfFs3

How would I go along doing this?

Answer 1

关于什么：

img = Image.open(GIF_FILENAME)
rgbimg = Image.new("RGBA", img.size)
rgbimg.paste(img)
rgbimg.save('foo.jpg')

[编辑]

创建了一个测试：

from PIL import Image
from collections import defaultdict
import pprint

img = Image.open("kEwfFs3.png")
rgbimg = Image.new("RGBA", img.size)
rgbimg.paste(img)

found_colors = defaultdict(int)
for x in range(0, rgbimg.size[0]):
    for y in range(0, rgbimg.size[1]):
        pix_val = rgbimg.getpixel((x, y))
        found_colors[pix_val] += 1 
pprint.pprint(dict(found_colors))

rgbimg.save('kEwfFs3.jpg')

那输出：

{(0, 0, 0, 255): 747802,
 (1, 1, 1, 255): 397,
 (2, 2, 2, 255): 299,
 (3, 3, 3, 255): 255,
 (4, 4, 4, 255): 221,
 (5, 5, 5, 255): 200,
 (6, 6, 6, 255): 187,
 (7, 7, 7, 255): 138,
 (8, 8, 8, 255): 160,
 (9, 9, 9, 255): 152,
 (10, 10, 10, 255): 122,
 (11, 11, 11, 255): 116,
 (12, 12, 12, 255): 144,
 (13, 13, 13, 255): 117,
 (14, 14, 14, 255): 117,
 (15, 15, 15, 255): 102,
 (16, 16, 16, 255): 119,
 (17, 17, 17, 255): 299641,
 (18, 18, 18, 255): 273,
 (19, 19, 19, 255): 233,
.................... etc .......
.................... etc .......
 (249, 249, 249, 255): 616,
 (250, 250, 250, 255): 656,
 (251, 251, 251, 255): 862,
 (252, 252, 252, 255): 1109,
 (253, 253, 253, 255): 1648,
 (254, 254, 254, 255): 2964175}

这是你所期望的。你的输出不一样吗？

Answer 2

I;16我在转换为 RGB 的（16 位灰度）tiff 时遇到了同样的问题。深入研究手册后发现问题与 PIL 用于将灰度图像转换为 RGB 的 lut 有关。它在 8 位色彩空间中工作；也就是说，它会剪切所有高于 255 的值。因此，一个快速简单的解决方案是使用您自己的 lut 手动转换为 RGB，该 lut 使用point方法在范围内缩放值，如下所示：

path = 'path\to\image'
img = Image.open(path)
img.point(lambda p: p*0.0039063096, mode='RGB')
img = img.convert('RGB')
img.show() # check it out!

我通过将 256 除以 16 位等效值 65535 来确定“lut”公式。