python - 在Python中将图像转换为灰度

Question

class PPM(object):
    def __init__(self, infile, outfile):
        self.infile=infile
        self.outfile=outfile

        #Read in data of image
        data= open(self.infile,"r")
        datain=data.read()
        splits=datain.split()

        #Header info
        self.type=splits[0]
        self.columns=splits[1]
        self.row=splits[2]
        self.colour=splits[3]
        self.pixels=splits[4:]

    def greysscale():
            for row in range(rows):
                for column in range(columns):
                    r, g, b = image.getPixel(row, column)
                    brightness = int(round(0.299 * r + 0.587 * g + 0.114 * b))
                    image.setPixel(row, column, color_rgb(brightness, brightness, brightness))


    def flattenred():
        for colour in range (0,len(self.pixels),3):
            self.pixels [colour]=str[0]

        return picture

    def writetofile(self):
        dataout= open(self.outfile,"w")
        dataout.write(self.type +"\n" + self.columns + "\n" + self.row +"\n"+ self.colour +"\n"+ " ".join (self.pixels))


sample= PPM("cake.ppm", "Replica.ppm")
sample.writetofile()

我在编写名为grey_scale的函数时遇到了麻烦，该函数通过对一个像素（红色，绿色和蓝色）的所有三个色号取平均值，然后将其全部替换为该平均值，将图片转换为灰度图像。
因此，如果这三种颜色分别为25、75和250，则平均值将为116，所有三个数字将变为116。
我该怎么做？

Answer 1

rom_file= [0,3,1]
#Main Function which adds s dots and xs to the deck list(s) depending on the data input file
def main():
    #Container for the output of the program, each nested list contains one row of the output
    decks = [[], [], [], [], []]
    #list that contains the number of empty rows for inputs 1-5(location of input given by [each - 1])
    empty_rows = [4, 3, 2, 1, 0]
    #Scan through each element of the list
    for each in from_file:
        #If the element 'each' is equal to 0, append a single dot to all 5 rows
        if each == 0:
            for i in range(5):
                decks[i].append('.')
        #If the input is in the range 1-5, define variables and the nested for loops
        else:
            #Maximum width of each pyramid
            max = (each * 2) - 1
            half_dots = int((max - 1) / 2)
            base_x = 1
            loc = each - 1
            #For loop that appends the max. number of dots to rows depending on data in empty_rows
            for every in range(empty_rows[loc]):
                decks[every].append(max * '.')
            #Primary for loop; appends the dots and xs to any row not covered by the previous loop (ALl rows that do not already have max dots) for each between 1-5
            for i in range(each):
                decks[i + empty_rows[loc]].append(half_dots * '.')
                decks[i + empty_rows[loc]].append(base_x * 'x')
                decks[i + empty_rows[loc]].append(half_dots * '.')
                half_dots -= 1
                base_x += 2
    #A loop that print out the results
    for each in decks:
        text = ""
        for i in each:
            text += i
        print(text)


#Starts the program by calling the main function
main()