使用Python进行图像裁剪

| 我是Python编码的新手,我正在编写一个程序,其中将裁剪输入的图像,然后将其保存在某个位置。现在,我可以结合使用PIL和pygame来做到这一点。但是问题是,当我从打开的pygame窗口中选择图像时,选择区域是完全不透明的,并且无法看透正在选择的区域。这给我的老板带来了麻烦,他希望能够按自己的选择进行查看。为了让你们更好地理解问题,我在这里编写代码:
import pygame, sys 
from PIL import Image 

pygame.init()

def displayImage( screen, px, topleft):
     screen.blit(px, px.get_rect())
     if topleft:
         pygame.draw.rect( screen, (128,128,128), pygame.Rect(topleft[0], topleft[1], pygame.mouse.get_pos()[0] - topleft[0], pygame.mouse.get_pos()[1] - topleft[1]))
     pygame.display.flip()  

def setup(path):
     px = pygame.image.load(path)
     screen = pygame.display.set_mode( px.get_rect()[2:] )
     screen.blit(px, px.get_rect())
     pygame.display.flip()
     return screen, px

def mainLoop(screen, px):
     topleft = None
     bottomright = None
     n=0
     while n!=1:
         for event in pygame.event.get():
             if event.type == pygame.MOUSEBUTTONUP:
                 if not topleft:
                     topleft = event.pos
                 else:
                     bottomright = event.pos
                     n=1
         displayImage(screen, px, topleft)
     return ( topleft + bottomright )

if __name__ == \"__main__\":
     input_loc=\"C:\\pic1.PNG\"
     output_loc=\"C:\\pic2.PNG\"
     screen, px = setup(input_loc)
     left, upper, right, lower = mainLoop(screen, px)
     im = Image.open(input_loc)
     im = im.crop(( left, upper, right, lower))
     pygame.display.quit()
     im.save(output_loc)
任何帮助表示赞赏。问候。     
已邀请:
我快速浏览并解决了其他一些问题。本质上,我的更改是这样做的: 在临时图像上绘制边界框,设置其Alpha透明度,然后将其在主图像上方变白。 避免不必要的绘制周期(当鼠标不动时,再次绘制同一图像毫无意义)。 确保宽度和高度始终为正。如果通过向左或向上拖动鼠标来绘制矩形,则您的代码将以负的宽度和/或高度结尾,从而在尝试写入最终图像时引发异常。 这是运行固定代码的屏幕截图: 我将代码分为两部分,以避免出现滚动条:
import pygame, sys
from PIL import Image
pygame.init()

def displayImage(screen, px, topleft, prior):
    # ensure that the rect always has positive width, height
    x, y = topleft
    width =  pygame.mouse.get_pos()[0] - topleft[0]
    height = pygame.mouse.get_pos()[1] - topleft[1]
    if width < 0:
        x += width
        width = abs(width)
    if height < 0:
        y += height
        height = abs(height)

    # eliminate redundant drawing cycles (when mouse isn\'t moving)
    current = x, y, width, height
    if not (width and height):
        return current
    if current == prior:
        return current

    # draw transparent box and blit it onto canvas
    screen.blit(px, px.get_rect())
    im = pygame.Surface((width, height))
    im.fill((128, 128, 128))
    pygame.draw.rect(im, (32, 32, 32), im.get_rect(), 1)
    im.set_alpha(128)
    screen.blit(im, (x, y))
    pygame.display.flip()

    # return current box extents
    return (x, y, width, height)
第2部分(与以上内容串联):
def setup(path):
    px = pygame.image.load(path)
    screen = pygame.display.set_mode( px.get_rect()[2:] )
    screen.blit(px, px.get_rect())
    pygame.display.flip()
    return screen, px

def mainLoop(screen, px):
    topleft = bottomright = prior = None
    n=0
    while n!=1:
        for event in pygame.event.get():
            if event.type == pygame.MOUSEBUTTONUP:
                if not topleft:
                    topleft = event.pos
                else:
                    bottomright = event.pos
                    n=1
        if topleft:
            prior = displayImage(screen, px, topleft, prior)
    return ( topleft + bottomright )

if __name__ == \"__main__\":
    input_loc = \'stack.png\'
    output_loc = \'out.png\'
    screen, px = setup(input_loc)
    left, upper, right, lower = mainLoop(screen, px)

    # ensure output rect always has positive width, height
    if right < left:
        left, right = right, left
    if lower < upper:
        lower, upper = upper, lower
    im = Image.open(input_loc)
    im = im.crop(( left, upper, right, lower))
    pygame.display.quit()
    im.save(output_loc)
    
samplebias的答案对我来说很棒。通过添加缩放和平移功能,我将其扩展到了正在处理的大图像。
import pygame, sys
from pygame.locals import K_a, K_s,K_w,K_d,K_LEFTBRACKET,K_RIGHTBRACKET

from PIL import Image
pygame.init()

BG_COLOR = (0,0,0)

def displayRect(screen, px, topleft, prior,pos,scale):
    # ensure that the rect always has positive width, height
    #topleft = [(val-pos[i])/scale for i,val in enumerate(topleft)]
    topleft = [(val/scale-pos[i]) for i,val in enumerate(topleft)]
    x, y = topleft
    bottomright = pygame.mouse.get_pos()
    width =  bottomright[0] - topleft[0]
    height = bottomright[1] - topleft[1]
    if width < 0:
        x += width
        width = abs(width)
    if height < 0:
        y += height
        height = abs(height)

    # eliminate redundant drawing cycles (when mouse isn\'t moving)

    current = x, y, width, height
    if not (width and height):
        return current
    if current == prior:
        return current

    # draw transparent box and blit it onto canvas
    rect = px.get_rect()
    px = pygame.transform.scale(px,[rect.width/scale, rect.height/scale])
    screen.blit(px, (rect[0]-pos[0],rect[1]-pos[1]))
    im = pygame.Surface((width, height))
    im.fill((128, 128, 128))
    pygame.draw.rect(im, (32, 32, 32), im.get_rect(), 1)
    im.set_alpha(128)
    screen.blit(im, (x, y))
    pygame.display.flip()

    # return current box extents
    return (x, y, width, height)

def setup(px):
    screen = pygame.display.set_mode( px.get_rect()[2:] )
    screen.blit(px, px.get_rect())
    pygame.display.flip()
    return screen, px

def move(pos,scale,px,screen):
    x,y = pos
    #print pos,x
    rect = px.get_rect()
    screen.fill(BG_COLOR)
    px = pygame.transform.scale(px,[rect.width/scale, rect.height/scale])
    screen.blit(px, (rect[0]-x,rect[1]-y))
    pygame.display.flip()
    #px.rect.topleft = pr.rect.topleft[0] - x, 

def mainLoop(screen, px, filelist):
    topleft = bottomright = prior = None
    n=0
    scale = 1
    pos = [0,0]
    while n!=1:
        for event in pygame.event.get():
            if event.type == pygame.MOUSEBUTTONUP:
                if not topleft:
                    topleft = [(val+pos[i])*scale for i,val in enumerate(event.pos)]
                    print \"tr: \",topleft
                else:
                    bottomright = [(val+pos[i])*scale for i,val in enumerate(event.pos)]
                    print \"br: \",bottomright
                    n=1

            if event.type == pygame.KEYDOWN and event.key == K_a:
                pos = [pos[0]-200,pos[1]]
                move(pos,scale,px,screen)
            if event.type == pygame.KEYDOWN and event.key == K_d:
                pos = [pos[0]+200,pos[1]]
                move(pos,scale,px,screen)
            if event.type == pygame.KEYDOWN and event.key == K_w:
                pos = [pos[0],pos[1]-200]
                move(pos,scale,px,screen)
            if event.type == pygame.KEYDOWN and event.key == K_s:
                pos = [pos[0],pos[1]+200]
                move(pos,scale,px,screen)


            if event.type == pygame.KEYDOWN and event.key == K_RIGHTBRACKET:
                scale = scale/1.25
                move(pos,scale,px,screen)
            if event.type == pygame.KEYDOWN and event.key == K_LEFTBRACKET:
                scale = scale*1.25
                move(pos,scale,px,screen)


        if topleft:
            prior = displayRect(screen, px, topleft, prior,pos,scale)

    return ( topleft + bottomright )
使用提供的主要功能samplebias。 谢谢堆栈溢出!     

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