wand: 如何 assemble 透明 gif / 清除每一帧的背景

Question

所以我有一系列透明的 png 并将它们附加到新的 Image()

with Image() as new_gif:
    for img_path in input_images:
        with Image(filename=img_path) as inimg:
            # create temp image with transparent background to composite
            with Image(width=inimg.width, height=inimg.height, background=None) as new_img:
                new_img.composite(inimg, 0, 0)
                new_gif.sequence.append(new_img)
    new_gif.save(filename=output_path)

很遗憾，添加新图像时背景不是 "cleared"。他们也会有最后一张图片：

但是如何清除背景呢？我虽然通过预先合成一个新图像来做到这一点..`：|哈普！！

我看到命令行 ImageMagick 有一个 similar 东西，但 wand 没有类似的东西。到目前为止，我必须使用合适的背景颜色来解决问题。

Answer 1

没有看到源图像，我可以假设 -set dispose background 是所需要的。对于 wand，您需要调用 wand.api.library.MagickSetOption 方法。

from wand.image import Image
from wand.api import library

with Image() as new_gif:
    # Tell new gif how to manage background
    library.MagickSetOption(new_gif.wand, 'dispose', 'background')
    for img_path in input_images:
        library.MagickReadImage(new_gif.wand, img_path)
    new_gif.save(filename=output_path)

或者...

您可以扩展魔杖来管理背景处理行为。这种方法将以编程方式为您提供 alter/generate 每个帧的好处。但不利的一面是 ctypes 需要做更多的工作。例如。

import ctypes
from wand.image import Image
from wand.api import library

# Tell python about library method
library.MagickSetImageDispose.argtypes = [ctypes.c_void_p, # Wand
                                          ctypes.c_int]    # DisposeType
# Define enum DisposeType
BackgroundDispose = ctypes.c_int(2)
with Image() as new_gif:
    for img_path in input_images:
        with Image(filename=img_path) as inimg:
            # create temp image with transparent background to composite
            with Image(width=inimg.width, height=inimg.height, background=None) as new_img:
                new_img.composite(inimg, 0, 0)
                library.MagickSetImageDispose(new_img.wand, BackgroundDispose)
                new_gif.sequence.append(new_img)
    # Also rebuild loop and delay as ``new_gif`` never had this defined.
    new_gif.save(filename=output_path)

<- 仍然需要延迟修正

wand: 如何 assemble 透明 gif / 清除每一帧的背景

wand: How to assemble transparent gif / clear background each frame

python

image

imagemagick

gif

wand