如何阻止枕头在我的动画 gif 中插入黑框

Question

我正在开发一个程序，该程序采用动画 gif 并将 gif 的 asciified 版本作为不同的动画 gif 返回 例子

asciify(foo.gif)
bar.gif has been created

在我制作 gif 并打开它后，动画开始处总是有一个黑框，这使得循环观看非常烦人。

我尝试将创建的 gif 的 alpha 通道设置为 0，并且只将 ascii_image_gifs[1,-1] 附加到输出 gif 中，但我已经没有想法了。

演示：

原图： trippy circles

输出 gif： trippy ascii circles elongated

编辑：我刚刚取得了突破！ gifify() 中的这一行是罪魁祸首：save_as = Image.new('RGBA', (self._nw*3, self._nh*8), (0, 0, 0, 0))

如果我把它改成save_as = Image.new('RGBA', (self._nw*3, self._nh*8), 'white')

黑框变成白色，所以我的问题变成了：如何在保存/创建输出图像时忽略Image.new() 创建的图像？

下面是程序，相关函数是gifify()

from PIL import Image, ImageFont, ImageDraw


__author__ = 'Nikolas'


ASCII_SHADING_CHARS = ['M', 'W', 'N', 'Q', 'B', 'H', 'K', 'R', '#', 'E', 'D', 'F', 'X', 'O', 'A', 'P', 'G', 'U', 'S',
                       'V', 'Z', 'Y', 'C', 'L', 'T', 'J', '$', 'I', '*', ':', '.', ' ']  # from darkest to lightest 32
#ASCII_SHADING_CHARS = ASCII_SHADING_CHARS[::-1]


class Asciify:
    def __init__(self, img, new_width=500):
        self.width, self.height = img.size  # image.size returns a 2 tuple (width, height) in pixels
        self._nw = new_width
        self._nh = int(new_width * self.height / self.width)
        self.im = img

    def grayify_and_resize(self):
        """
        Split the GIF into individual frames. Resize and convert each frame to monochrome.
        :returns: a list of resized black&white Image objects
        """

        new_width = self._nw
        new_height = self._nh
        num_frames = self.im.n_frames  # number of frames in the .gif animation
        result_list = []
        for i in range(0, num_frames - 1):
            # convert to mode L (b&w); resize to new dimensions
            result_list.append(self.im.convert('L').resize((int(new_width), new_height)))
            self.im.seek(self.im.tell() + 1)  # move to the next frame in the gif animation

        return result_list

    def ascii_map(self, im_list, color_width=int(255 / len(ASCII_SHADING_CHARS))):
        """
        Maps an ascii shading character to a pixel of each frame of the GIF
        :param im_list: a list of black and white Image objects
        :param color_width: determines the color intensity of each pixel
        :returns: a list of each frame of the gif converted to ascii pixels
        """

        ascii_image_list = []  # unformatted ascii images; needs to be broken into proper rows and columns
        result_list = []  # ascii_image_list broken into proper rows and columns; how convinient
        for image in im_list:
            pixels = image.getdata()  # color data on every pixel per image
            append_list = []  # temporary list to append to ascii_image_list
            for pixel_value in pixels:
                index = int(pixel_value // color_width)
                if index >= len(ASCII_SHADING_CHARS):
                    append_list.append(ASCII_SHADING_CHARS[-1])
                else:
                    append_list.append(ASCII_SHADING_CHARS[index])  # 'replace' pixel with ascii char
            ascii_image_list.append(append_list)  # adds an element to ascii_image_list containing every pixel for image

        for ascii_image in ascii_image_list:
            ascii_string = "".join(ascii_image)
            result_list.append([ascii_string[index:index + self._nw]
                                for index in range(0, len(ascii_string), self._nw)])

        return result_list

    def gifify(self, ascii_image_list):
        """
        Return the ascii strings to .gif format for use in a traditional image viewer.
        :param ascii_image_list: A list of ascii 'pixel' images
        :returns: None
        """

        # 7 = nw*4, nh*10
        # 5 = nw*3, nh*8
        font = ImageFont.truetype('ascii.ttf', 5)  # set font and font size
        ascii_image_strings = ['\n'.join(image) for image in ascii_image_list]
        ascii_image_gifs = []
        for image in ascii_image_strings:
            #print(image)
            if image == ascii_image_strings[0]:
                continue
            temp_image = Image.new('RGBA', (self._nw*3, self._nh*8), (255,255,255,0))  # should be transparent, didn't work
            image_draw = ImageDraw.Draw(temp_image)
            image_draw.text((0, 0), image, font=font, fill='black')
            temp_image.resize((self._nw, self._nh))
            ascii_image_gifs.append(temp_image)
            if image == ascii_image_strings[-1]:
                save_as = Image.new('RGBA', (self._nw*3, self._nh*8), (0, 0, 0, 0))  # should also be transparent, didn't work
                save_as.save('temp.gif', save_all=True, append_images=ascii_image_gifs, loop=0, fps=24)
                save_as.close()


if __name__ == "__main__":
    im = Image.open("trippy.gif")
    asciify_im = Asciify(im, 110)
    gif_list = asciify_im.grayify_and_resize()
    ascii_images = asciify_im.ascii_map(gif_list)
    asciify_im.gifify(ascii_images)

    # Debugging ascii image creation #
    # outfile = open("outfile.txt", 'w')
    # for image in ascii_images:
    #    outfile.write("\n".join(image) + '\n\n')

Answer 1

感觉这个参数 append_images=ascii_image_gifs 正在将该图像列表附加到现有的全黑图像。

你是 100% 正确的。

致电image.save("test.gif", append_images=images)。那么image 是第一帧，images 是所有额外/附加帧的列表。

因此，改为使用images[0] 作为第一帧，并附加其余帧 (images[1:])。

---

在您的代码中save_as 是黑框的原因。所以改为删除它，只使用ascii_image_gifs。

 ascii_image_gifs[0].save('temp.gif', save_all=True, append_images=ascii_image_gifs[1:], loop=0, fps=24)

这可能有点令人费解，但这就是它与 PIL 的工作方式。