如何在imagemagick中调整图像大小但保持宽高比不变 [英] How to resize an image in imagemagick but keep an aspect ratio constant

问题描述

我正在尝试使用imagemagick调整图像的大小以保持其当前的长宽比，但将其装入4/3容器中.

I am trying to resize an image (using imagemagick) to keep it's current aspect ratio but fit it into a 4/3 container.

这是我到目前为止的命令:

This is the command I have so far:

magick convert ./horse.jpeg -background white -gravity center -extent 4/3 ./hourse_output.jpeg

这就是我想要的:.如您所见，图像被放入"一个4/3容器中.

This is what I'd like: . As you can see, the image is "put into" a 4/3 container.

推荐答案

我的错误.诸如ImageMagick -extent中的4:3之类的宽高比只会裁切而不会填充.

My error. The aspect ratios such as 4:3 in ImageMagick -extent will only crop and not pad.

在 http://www.fmwconcepts.com/上查看我的bash Unix脚本"aspectpad" imagemagick/index.html ，它可以满足您的要求.

See my bash unix script "aspectpad" at http://www.fmwconcepts.com/imagemagick/index.html, which does what you want I think.

尽管如此，这是部分解决方案.但这仅适用于横向模式输入.由于对-extent使用了内联参数，因此也仅适用于ImageMagick 7.您必须将其修改为纵向模式.

Nevertheless, here is a partial solution for how to do it. But this only works for landscape mode input. Also only with ImageMagick 7 due to the use of inline arguments for -extent. You would have to modify it for portrait mode.

输入(纵横比2:1 = 2/1 = 2):

Input (aspect 2:1 = 2/1 = 2):

magick barn_2to1.jpg -set option:wd "%[fx:(4/3)>(w/h)?(4/3*h):w]" -set option:ht "%[fx:(4/3)>(w/h)?h:(w/(4/3))]" -gravity center -background black -extent "%[wd]x%[ht]" result.jpg

输出(纵横比4:3 = 4/3 = 1.33):

Output (aspect 4:3 = 4/3 = 1.33):

请注意，我使用了黑色背景，因此在这里可见.更改为您想要的任何其他颜色.

Note, that I used background of black so that it was visible here. Change to any other color you want.

如果输入横向宽高比大于4:3(4/3)，它将在顶部/底部填充.如果输入横向宽高比小于4:3，它将在左/右上滑动.

If the input landscape aspect is larger than 4:3 (4/3), it will pad on top/bottom. If the input landscape aspect is smaller than 4:3, it will pad on left/right.

输入(长宽比= 1:1 = 1/1 = 1):

Input (aspect=1:1 = 1/1 = 1):

magick lena.jpg -set option:wd "%[fx:(4/3)>(w/h)?(4/3*h):w]" -set option:ht "%[fx:(4/3)>(w/h)?h:(w/(4/3))]" -gravity center -background black -extent "%[wd]x%[ht]" result2.jpg

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