PPM图像到Python中的ASCII艺术

Question

我必须创建一个程序,从命令行读取文件并将其转换为ASCII艺术.我使用的是PPM格式,这里是项目的链接.

这是我到目前为止:

import sys

def main(filename):
    image = open(filename)
    #reads through the first three lines
    color = image.readline().splitlines()
    size_width, size_height = image.readline().split()
    max_color = image.readline().splitlines()

    #reads the body of the file
    pixels = image.read().split()
    red = 0
    green = 0
    blue = 0
    r_g_b_value = []
    #pulls out the values of each tuple and coverts it to its grayscale value 
    for i in pixels:
        if i !=  "\n" or " ":
            if len(i) == 3:
                red = int(i[0]) * .3
                green = int(i[1]) * .59
                blue = int(i[2]) * .11
            elif len(i) == 2:
                red == int(i[0]) * .3
                green == int(i[1]) *.59
                blue == 0
            elif len(i) == 1:
                red == int(i[0]) * .3
                green == 0
                blue == 0

            r_g_b_value = [red + green + blue]

            character = []
        for j in len(r_g_b_value):
            if int(j) <= 16:
                character = " "
            elif int(j) > 16 and int(j) <= 32:
                character = "."
            elif int(j) > 32 and int(j) <= 48:
                character = ","
            elif int(j) > 48 and int(j) <= 64:
                charcter = ":"
            elif int(j) > 64 and int(j) <= 80:
                character = ";"
            elif int(j) > 80 and int(j) <= 96:
                character = "+"
            elif int(j) > 96 and int(j) <= 112:
                character = "="
            elif int(j) > 112 and int(j) <= 128:
                character = "o"
            elif int(j) > 128 and int(j) <= 144:
                character = "a"
            elif int(j) > 144 and int(j) <= 160:
                character = "e"
            elif int(j) > 160 and int(j) <= 176:
                character = "0"
            elif int(j) > 176 and int(j) <= 192:
                character = "$"
            elif int(j) > 192 and int(j) <= 208:
                character = "@"
            elif int(j) > 208 and int(j) <= 224:
                character = "A"
            elif int(j) > 224 and int(j) <= 240:
                character = "#"
            else:
                character = "M"

            grayscale = character
            print(grayscale)

main(sys.argv[1])

我得到一个错误,说'int'对象不可迭代,是否有一种简单的方法可以解决这个问题,有人会建议在保留图像时将其打印出来.

我不确定的最后一件事是如何保持图片的宽度和高度.

任何帮助将不胜感激.

Answer 1

您可以image-to-ansi.py用于转换.

首先,下载image-to-ansi.py:

wget https://gist.githubusercontent.com/klange/1687427/raw/image-to-ansi.py

将此脚本另存为ppmimage.py:

# Parses a PPM file and loads it into image-to-ansi.py
import re, itertools

sep = re.compile("[ \t\r\n]+")

def chunks(iterable,size):
    """ http://stackoverflow.com/a/434314/309483 """
    it = iter(iterable)
    chunk = tuple(itertools.islice(it,size))
    while chunk:
        yield chunk
        chunk = tuple(itertools.islice(it,size))

""" Emulates the Image class from PIL and some member functions (`getpixel`, `size`). """
class Image:
    """ This class emulates the PIL Image class, and it can parse "plain" PPM's.
        You can use PIL instead. """
    @staticmethod
    def fromstdin():
        return Image()
    def __init__(self): # http://netpbm.sourceforge.net/doc/ppm.html
        self.entities = sep.split("\n".join(list(filter(lambda x: not x.startswith("#"), sys.stdin.read().strip().split("\n")))))
        self.size = tuple(list(map(int,self.entities[1:3])))
        self.high = int(self.entities[3]) # z.b. 255
        self.pixels = list(map(lambda x: tuple(map(lambda y: int(int(y) / self.high * 255), x)), list(chunks(self.entities[4:], 3))))
    def getpixel(self, tupl):
        x = tupl[0]
        y = tupl[1]
        pix = self.pixels[y*self.size[0]+x]
        return pix

image_to_ansi = __import__("image-to-ansi") # __import__ because of minuses in filename. From https://gist.github.com/1687427

if __name__ == '__main__':
    import sys
    #import Image
    im = Image.fromstdin() # use Image.open from PIL if using PIL
    for y in range(im.size[1]):
        for x in range(im.size[0]):
            p = im.getpixel((x,y))
            h = "%2x%2x%2x" % (p[0],p[1],p[2])
            short, rgb = image_to_ansi.rgb2short(h)
            sys.stdout.write("\033[48;5;%sm " % short)
        sys.stdout.write("\033[0m\n")
    sys.stdout.write("\n")

您可以像这样测试脚本(假设您已安装netpbm并imagemagick安装):

convert -resize $(($COLUMNS*2))x$(($LINES*2)) logo: pnm:- | pnmtoplainpnm | python3 ppmimage.py

在我的机器上,它看起来像这样:

Answer 2

我不久前用 C# 编写了其中一个，并计算了要使用以下公式的字符：

index_into_array = (int)(r_g_b_value * (chars_array_length / (255.0)));

至于宽度和高度，您可以平均每两行垂直像素，将高度减半。

编辑1：回应评论：基本思想是将RGB值从0到255缩放到0到数组的长度，并将其用作索引。

编辑 2：更新以纠正我忽略您的灰度标准化的情况。