ImageMagick Gravity parameter

Question

I'm trying to create a process to automatically generate thumbnails of the images uploaded to my website.

I'm using this command line:

-thumbnail "120x90>" -quality 95 -background transparent -gravity Center -extent 120x90 img.png

The thumbnail is generated without problems, with the correct aspect ratio. but the option -gravity center seems that is doing nothing, the actual image is always aligned to the left of the canvas, when i want it centered...Am i missing something?

test input:

Result:

score 2 · Answer 1 · edited Jun 19 '19 at 16:06

2

If your source images have a similar aspect ratio to your thumbnails, there may be nothing to crop, and that's why it doesn't seem like -gravity is having any effect. For example, if you change -extent to 50x50, then play with -gravity, you'll see changes in the alignment.

Edit (update for comments):

Here's the result I got using this command-line with your sample image:

convert.exe -thumbnail "120x90>" -quality 95 -background transparent -gravity Center -extent 120x90 monalisa171p.jpg monalisa171p_thumb.jpg

_{(source: datageist.com)}

I don't know if that helps, but it seems to work.

edited Jun 19 '19 at 16:06

Glorfindel

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answered Feb 21 '10 at 14:44

datageist

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I'm using a 337x500px image for testing. The result is a 120x90 px image with all the right-side filled with blank pixels. The entire image is a aligned to left. – Drevak Feb 21 '10 at 15:16
updated with and example. You will see that the image is not centered on the canvas, but aligned to the left. – Drevak Feb 21 '10 at 15:23

score 0 · Accepted Answer · answered Feb 21 '10 at 16:55

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Updated the convert.exe with the latest release from www.imagemagick.org and...tada! problem solved.

answered Feb 21 '10 at 16:55

Drevak

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ImageMagick Gravity parameter

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