平滑放大图像的像素

Question

我对编程很陌生，尝试学习Python。我试图通过取每个像素及其相邻像素的平均值来平滑图像的像素。我成功地运行了以下内容。在

from cImage import *
import statistics as s


def smoothImg(oldimage):
    theWindow = ImageWin("Smooth Image",1200,1200)
    theImage = FileImage(oldimage)
    theImage.draw(theWindow)

    height = theImage.getHeight()
    width = theImage.getWidth()

    newImage = EmptyImage(width,height)

    for row in range(height):
        for col in range(width):
            try:
                pixelVal = theImage.getPixel(col-1,row-1)
            except:
                pixelVal = theImage.getPixel(col,row)  #maybe change to "pass"
            try:
                pixelVal2 = theImage.getPixel(col-1,row)
            except:
                pixelVal2 = theImage.getPixel(col,row)
            try:
                pixelVal3 = theImage.getPixel(col-1,row+1)
            except:
                pixelVal3 = theImage.getPixel(col,row)
            try:
                pixelVal4 = theImage.getPixel(col,row-1)
            except:
                pixelVal4 = theImage.getPixel(col,row)
            pixelVal5 = theImage.getPixel(col,row)
            try:
                pixelVal6 = theImage.getPixel(col,row+1)
            except:
                pixelVal6 = theImage.getPixel(col,row)
            try:
                pixelVal7 = theImage.getPixel(col+1,row-1)
            except:
                pixelVal7 = theImage.getPixel(col,row)
            try:
                pixelVal8 = theImage.getPixel(col+1,row+1)
            except:
                pixelVal8 = theImage.getPixel(col,row)
            try:
                pixelVal9 = theImage.getPixel(col+1,row)
            except:
                pixelVal9 = theImage.getPixel(col,row)

            redMean = s.mean([pixelVal[0],pixelVal2[0],pixelVal3[0],pixelVal4[0],pixelVal5[0],pixelVal6[0],pixelVal7[0],pixelVal8[0],pixelVal9[0]])
            greenMean = s.mean([pixelVal[1],pixelVal2[1],pixelVal3[1],pixelVal4[1],pixelVal5[1],pixelVal6[1],pixelVal7[1],pixelVal8[1],pixelVal9[1]])
            blueMean = s.mean([pixelVal[2],pixelVal2[2],pixelVal3[2],pixelVal4[2],pixelVal5[2],pixelVal6[2],pixelVal7[2],pixelVal8[2],pixelVal9[2]])

            meanPixel = Pixel(redMean,greenMean,blueMean)
            newImage.setPixel(col,row,meanPixel)


    newImage.setPosition(width+1,0)
    newImage.draw(theWindow)

    theWindow.exitOnClick()
    return

这个程序似乎有效，但我无法想象这是最好的方法。另外，我希望能够获得更广泛的像素平均值，而不仅仅是一个近邻。我试着在for循环中运行这个函数，但是它给了我一个完全灰色的图像。在

^{pr2}$

这个问题取自“上下文中的Python编程”。第222页练习6.25。在