Create a gif out of multiple png files and retain the original size

[searene]

I have multiple png files, all of them are of size 575x500, I created a gif out of those png files using the following command:

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convert -delay 100 -loop 0 *.png a.gif

It worked, except the size of a.gif was 1920x1080, which was the same as my screen resolution. Most areas of the gif is transparent, only an area of size 575x500 in the middle is not, and this area is what I want.

I would like to ask if there's any way to remove those transparent areas? I only want a gif with the size of 575x500.

[snibgo]

I have multiple png files, all of them are of size 575x500, ...

Is that true? What is the text output from "identify *.png"?

I suspect your inputs have a larger canvas. If so, it can be removed with "+repage" after the inputs:

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convert -delay 100 -loop 0 *.png +repage a.gif

[searene]

Hi snibgo,

Thank you for your reply and suggestion.

These png files are originally 1920x1080, I cropped them to 575x500 using this command.

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mogrify -crop 575x500+715+322 *.png

This is the output of identify *.png:

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➜  Desktop identify *.png
2017-04-15-160537_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 173c 3.41KB 0.000u 0:00.000
2017-04-15-160607_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 10.3KB 0.000u 0:00.000
2017-04-15-160618_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 10.3KB 0.000u 0:00.000
2017-04-15-160808_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 14KB 0.000u 0:00.000
2017-04-15-160819_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 13KB 0.000u 0:00.000
2017-04-15-160847_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 16.4KB 0.000u 0:00.000
2017-04-15-160858_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 17.3KB 0.000u 0:00.000
2017-04-15-160913_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 19.3KB 0.000u 0:00.000
2017-04-15-160946_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 20.3KB 0.000u 0:00.000
2017-04-15-161002_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 21.5KB 0.000u 0:00.000
2017-04-15-161012_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 21.1KB 0.000u 0:00.000
2017-04-15-161020_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 19.9KB 0.000u 0:00.000
2017-04-15-161046_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 23KB 0.000u 0:00.000
2017-04-15-161053_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 24.7KB 0.000u 0:00.000
2017-04-15-161119_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 26.1KB 0.000u 0:00.000
2017-04-15-161123_1920x1080_scrot.png PNG 575x500 1920x1080+715+322 8-bit sRGB 256c 12.9KB 0.000u 0:00.000

I guess it meant the size of those png files were all 575x500? And it also pointed out those images were cropped out from images of size 1920x1080, with offset 715 and 322.

I just tried the command you provied, and it worked pretty well!

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convert -delay 100 -loop 0 *.png +repage a.gif

I'm still curious why the original gif file, which was created without +repage, was of size 1920x1080.

[snibgo]

I'm still curious why the original gif file, which was created without +repage, was of size 1920x1080.

That's because you didn't have "+repage" when you created the PNG files, so they ended up with a canvas size of 1920x1080. The canvas size doesn't merely mean the image was cropped. It means the image sits on a larger canvas, at a certain offset.

After "-crop", you should always consider putting "+repage", because in many circumstances (such as here) you don't want the canvas data. See http://www.imagemagick.org/script/comma ... s.php#crop

[searene]

Hi snibgo,

Thanks for the explanation, it's very clear.

[fmw42]

If the rest of the image is transparent or constant color, you could try

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convert -delay 100 *.png -coalesce -trim +repage -loop 0 -layers optimize a.gif