Question

是否有已知的解决方案将图像从3个通道（ RGB ）转换为只使用PIL（或Scipy）的一个通道

我尝试将图片转换为Grayscale并按照下面的代码保存为png，图片仍然有3个颜色通道。

from glob import glob
import os
import os.path
from PIL import Image

SIZE = 32, 32

# set directory
# os.chdir('..data/unprocessed_cats')

# filter all jpg and png images
IMAGE_FILES = glob('../data/validation/cats/*.jpg')

IMAGE_COUNTER = 1
print IMAGE_FILES
# iterate over files
for image_file in IMAGE_FILES:

    # open file and resize
    try:
        im = Image.open(image_file)
    except:
        pass
    im = im.resize(SIZE, Image.ANTIALIAS)

    # save locally
    output_filename = "%s.png" % IMAGE_COUNTER
    # Grayscale
    im.convert('LA').save(os.path.join('../data/validation', 'cats_processed', output_filename), "PNG")


    # incriment image counter
    IMAGE_COUNTER = IMAGE_COUNTER + 1

Answer 1

我尝试使用im.convert('L')，但用黑色取代透明度（将整个图像变黑）。

我发现Remove transparency/alpha from any image using PIL的以下代码非常有帮助（Humphrey的全部学分）：

def remove_transparency(im, bg_colour=(255, 255, 255)):

    # Only process if image has transparency 
    if im.mode in ('RGBA', 'LA') or (im.mode == 'P' and 'transparency' in im.info):

        # Need to convert to RGBA if LA format due to a bug in PIL 
        alpha = im.convert('RGBA').split()[-1]

        # Create a new background image of our matt color.
        # Must be RGBA because paste requires both images have the same format

        bg = Image.new("RGBA", im.size, bg_colour + (255,))
        bg.paste(im, mask=alpha)
        return bg

    else:
        return im

首先删除透明度，然后使用im.convert('L')进行转换，将返回灰度模式：

im = remove_transparency(im).convert('L')

使用PIL或Scipy将Python图像从RGB转换为单通道

1 个答案: