如何转换base64图像？ [英] How do I convert a base64 image?

问题描述

我正在尝试使用ImageMagick中的convert命令行工具。我有一个base64编码的png文件，我需要将其转换为另一种格式。我正在查看文档和论坛讨论，这表明我应该可以使用这种语法：

I am trying to use the "convert" command-line tool from ImageMagick. I have a base64 encoded png file and I need to convert it to another format. I am looking at documentation and a forum discussion which suggests that I should be able to use this syntax:

convert inline:file.txt file.jpg

但是，当我这样做时，我收到此错误消息：

But when I do this, I get this error message:

convert: corrupt image `file.txt' @ error/constitute.c/ReadInlineImage/910.

我做错了什么？如何转换为读取base64图像文件？

What am I doing wrong? How do I get convert to read a base64 image file?

推荐答案

更新答案 - 现在我自己更好地理解： - ）

Updated Answer - now that I understand it better myself :-)

基本上，您可以使用 openssl 对此图像进行base64编码，如下所示：

Basically, you can base64 encode an image using openssl like this:

openssl enc -base64 -in image.png > image.b64

但是，如果你想要 ImageMagick 为了能够阅读它，你需要一个小的标题，告诉 ImageMagick 接下来的内容。标题必须包含：

However, if you want ImageMagick to be able to read it, you need a small header at the start, to tell ImageMagick what follows. The header must contain:

data:image/png;base64,

后面是使用上面的 openssl 命令生成的base64编码数据。所以，根据shell的功能，你可以在 bash 中使用复合语句这样做：

followed by your base64 encoded data generated using the openssl command above. So, depending on what features your shell has, you could do it like this with a compound statement in bash:

{ echo "data:image/png;base64,"; openssl enc -base64 -in input.png; } > image.b64

或在Windows中这样：

or like this in Windows:

echo data:image/png;base64,         > image.b64
openssl enc -base64 -in image.png  >> image.b64

一旦你有了那种格式的图像，你就可以继续处理它了 ImageMagick 喜欢这样：

Once you have the image in that format, you can then proceed to process it with ImageMagick like this:

convert inline:image.b64 result.png

对于在css中使用此功能的用户，请添加 -A 标记为一行输出

For those who use this in css, add -A flag to output in one line

openssl enc -base64 -A -in image.png > image.b64

原始答案

经过多次试验，我可以做到！ ： - ）

After MUCH experimenting, I can do it!!! :-)

从Eric（@emcconville）设置开始：

Start with Eric's (@emcconville) setup:

# For example
convert rose: rose.png
# Create base64 file
openssl enc -base64 -in rose.png -out rose.txt

现在将这个混乱添加为最后一行：

and now add this mess as the last line:

{ echo "data:image/png;base64,"; cat rose.txt; } | convert inline:- out.jpg

我想数据：image / png ; base64，不存在于由 openssl 创建的base64文件中，因此我创建了一个复合语句，将该文件加上 stdin ImageMagick 。

I guess the data:image/png;base64, is not present in the base64 file created by openssl so I create a compound statement that sends that plus the file to stdin of ImageMagick.

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