缩放图片的一部分

Question

我想放大图片的一部分，在本例中是一个鼻子。

我有一个功能来选择我要放大的图片部分。

def copyAndPaste(picture):
  height = getHeight(picture)
  width = getWidth(picture)
  newPicture = makeEmptyPicture(width, height)
  for x in range(width):
    for y in range(height):
      pxl = getPixel(picture,x,y)
      if (x>48 and x<59) and (y>58 and y<71):
        newPxl =getPixel(newPicture, #?,#?)
      else:
        newPxl = getPixel(newPicture, x,y)
      color = getColor(pxl)
      setColor(newPxl,color)

  return newPicture

def d():    
  f=pickAFile()
  picture=makePicture(f)        
  newPicture = copyAndPaste(picture)        
  writePictureTo(newPicture, r"D:\FOLDER\0Pic4.jpg")
  explore (newPicture)

我还有放大图片的功能：

def Enlarge(picture):
  height = getHeight(picture)
  width = getWidth(picture)
  newPicture = makeEmptyPicture(width*2, height*2)
  x1=0
  for x in range(0,width):
    y1=0
    for y in range(0,height):
      pxl = getPixel(picture,x,y)
      newPxl = getPixel(newPicture, x1,y1)
      color = getColor(pxl)
      setColor(newPxl,color)

      y1=y1+2
    x1=x1+2

  return newPicture

例如。
从：

要：

我尝试了很多东西，但是无法弄清楚如何将两者结合起来放大图片的一部分，让图片的其余部分保持清晰。

这就是生成的图片应该是什么样子（尽管很荒谬），

我一直在练习小图像，因为程序执行时间太长，在这个阶段使用较大的图像是不可行的，这意味着结果是粗略的，但至少会显示它是否有效。

Answer 1

我仍然不确定我理解你要做什么，但我认为它是这样的：你想复制并粘贴鼻子，而不是 cut和粘贴，并且您希望粘贴的副本以与第二个示例相同的方式加倍。

因此，脸部中间会有一个10x10的鼻子，右下方会有一个20x20的褪色鼻子。

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首先，要复制和粘贴，您只需将像素复制到新旧位置，而不是仅复制到新位置：

def copyAndPaste(picture):
  height = getHeight(picture)
  width = getWidth(picture)
  newPicture = makeEmptyPicture(width+100, height+100)
  for x in range(width):
    for y in range(height):
      pxl = getPixel(picture,x,y)
      color = getColor(pxl)
      if (x>48 and x<59) and (y>58 and y<71):
        newPxl =getPixel(newPicture, x+100,y+100)
        setColor(newPxl,color)
      newPxl = getPixel(newPicture, x,y)
      setColor(newPxl,color)

现在，要放大新粘贴的副本，您只需要将偏移量加倍。换句话说，49,59处的第一个像素变为149,159，但50,60处的像素变为151,161，而51,61处的像素变为153,163，依此类推。

所以，你想要的是从49,59获得距离，加倍，将其加回到49,59，然后将其移动100,100：

      if (x>48 and x<59) and (y>58 and y<71):
        newPxl =getPixel(newPicture, (x-49)*2+49+100,(y-59)*2+59+100)
        setColor(newPxl,color)

Answer 2

这只是为了记录和乐趣，而不是答案......

但正如提到的abarnert（"Are you sure they just want you to leave 3 white pixels for every copied pixel, rather than copying the same pixel 4 times?"），这是一个非常荒谬的缩放算法......

更有趣但基本的图像缩放方法是Nearest Neighbor Algorithm。

def EnlargeNearestNeighbor(picture, multiplier):

  w1 = getWidth(picture)
  h1 = getHeight(picture)
  w2 = getWidth(picture) * multiplier
  h2 = getHeight(picture) * multiplier

  x_ratio = w1/float(w2)
  y_ratio = h1/float(h2)

  newPicture = makeEmptyPicture(w2, h2)

  for x in range(0, w2):
    for y in range(0, h2):
      newPx = getPixel(newPicture, x, y)

      px = floor(x*x_ratio);
      py = floor(y*y_ratio);

      oldPx = getPixel(picture, int(px), int(py))
      setColor(newPx, getColor(oldPx))

  return newPicture

file = pickAFile()
picture = makePicture(file)
pic = EnlargeEagle(picture)

pic2 = EnlargeNearestNeighbor(picture, 3)

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其他有趣的算法here。

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以下是Eagle Algorithm的基本实现（适用于具有少量不同颜色的图像）：

def EnlargeEagle(picture):

  w = getWidth(picture)
  h = getHeight(picture)
  w2 = getWidth(picture)*2
  h2 = getHeight(picture)*2

  newPicture = makeEmptyPicture(w2, h2)

  x2 = 0
  for x in range(1, w-1):
    y2 = 0
    for y in range(1, h-1):

      oldPxS = getPixel(picture, x-1, y-1)
      oldPxT = getPixel(picture, x, y-1)
      oldPxU = getPixel(picture, x+1, y-1)

      oldPxV = getPixel(picture, x-1, y)
      oldPxC = getPixel(picture, x, y)
      oldPxW = getPixel(picture, x+1, y)

      oldPxX = getPixel(picture, x-1, y+1)
      oldPxY = getPixel(picture, x, y+1)
      oldPxZ = getPixel(picture, x+1, y+1)

      newPx1 = getPixel(newPicture, x2, y2)
      newPx2 = getPixel(newPicture, x2+1, y2)
      newPx3 = getPixel(newPicture, x2, y2+1)
      newPx4 = getPixel(newPicture, x2+1, y2+1)

      # Step 1
      c = getColor(oldPxC)
      setColor(newPx1, c)
      setColor(newPx2, c)
      setColor(newPx3, c)
      setColor(newPx4, c)

      # Step 2      
      if (getColor(oldPxV) == getColor(oldPxS)) and (getColor(oldPxS) == getColor(oldPxT)):
         setColor(newPx1, getColor(oldPxS))

      if (getColor(oldPxT) == getColor(oldPxU)) and (getColor(oldPxU) == getColor(oldPxW)):
         setColor(newPx2, getColor(oldPxU))

      if (getColor(oldPxV) == getColor(oldPxX)) and (getColor(oldPxX) == getColor(oldPxY)):
         setColor(newPx3, getColor(oldPxX))

      if (getColor(oldPxW) == getColor(oldPxZ)) and (getColor(oldPxZ) == getColor(oldPxY)):
         setColor(newPx4, getColor(oldPxZ))



  y2 += 2
x2 += 2

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