Controlling opacity when overlaying an image

[hollymcr]

I'm trying to do something that feels like it should be fairly straightforward but I'm getting into a mess....

I need to take old.png, resize to 400x400, and overlay a watermark (wmark.png), to create new.png.

This works:

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composite -gravity center "wmark.png" \( "old.png" -resize 400x400 \) "wmark.png" "new.png"

However, I would like to control the opacity of the overlaid wmark.png and I can't see how to do that.

Feel free to throw away what I have already! I've struggled to achieve both the resize and the overlay in one step.

[Bonzo]

Have you tried -watermark

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composite -watermark 30% -gravity center watermark.png input.jpg output.png

To combine both you will need to "pipe" the result of one to the other with something like ( this probably will not work as is ! ):

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convert input.jpg -resize 500x500 miff:- | composite -watermark 30% -gravity center watermark.png - output.png

[hollymcr]

Have you tried -watermark

I have but I've never got the hang of it.

To combine both you will need to "pipe" the result of one to the other with something like ( this probably will not work as is ! ):

Code: Select all

convert input.jpg -resize 500x500 miff:- | composite -watermark 30% -gravity center watermark.png - output.png

[/quote]

It's a great starting point, as it does work!

However, I'm not sure what criteria define a suitable wmark.png when using this method, as the results are poor with the watermark image I am using. If I remove the -watermark I get similar results as I was getting before, I'm just still stuck on the opacity of the watermark.

Experimenting a little more, however, gets me something which does work using -dissolve:

Code: Select all

convert input.jpg -resize 500x500 miff:- | composite -dissolve 30% -gravity center watermark.png - output.png

So thanks for your method, it got me there in the end!

[anthony]

Annotating, Watermarking Images..
http://www.imagemagick.org/Usage/annota ... termarking

This is one of the oldest set of Examples in IM Examples!