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Make round card corners with transparency

PostPosted: 14 Aug 2017, 16:22
by Ekkaiaa
I coded a script for get complete card sets into Xmage format (more info, if anyone interested:

Many times image cards comes with ugly white or black corners, where supposed to be rounded. So using (the famous) Imagemagick I managed to get rid of it, and mantaining transparency (alpha channel, png format) so looks nice and roundy in softwares, websites... :)

So I think this could be useful for more people, here is the commands you need.

First, install Imagemagick in the system you're using.
Now you can execute this commands in your cmd/console (and of course, complete with your scripts).

First you need to make the "round border" overlay for the cards with this command, only need one time for the cards (if all are in the same size).

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convert -size 488x680 xc:none -draw "roundrectangle 0,0,488,680,25,25" mask.png
As you can see, 488x680 is the size in px, and the two "25" are too important, it's the "quantity" of round corner that will apply, so maybe you need to tweak-test a bit, comparing with another rounded cards for test.

Now with this you "glue" the round overlay with the card and export. Notice that you may name it with .png extension, if not, alpha channel will not save.

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convert "card.jpg" -matte mask.png -compose DstIn -composite "card.png"
And now you have the card with round corners. If you wanna resize the result (not important):

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convert "card.png" -resize 265x370 -alpha on "card.png"
Now you only must complete the scritps with foreach for files in a folder, etc.

P.S. For Xmage .png extension will not work, but just renaming (not converting) to ".jpg" all goes ok:

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ren *.png *.jpg
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rename 's/.png$/.jpg/' *.png


I also made a simply .bat to drag-n-drop a image and round it. The difference it's mainly that round-size-layer it's automated with imagemagick "identify". The rest are the same.

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FOR /F "tokens=1 delims=" %%A in ('identify -format %%[fx:h] %1') do SET alto=%%A
FOR /F "tokens=1 delims=" %%A in ('identify -format %%[fx:w] %1') do SET ancho=%%A

convert -size %ancho%x%alto% xc:none -draw "roundrectangle 0,0,%ancho%,%alto%,19,19" mask.png

convert %1 -matte mask.png -compose DstIn -composite "result.png"

del mask.png

ren *.png *.jpg
Save it in a .bat file and drag a card image.

Re: Make round card corners with transparency

PostPosted: 15 Aug 2017, 00:16
by kudit
PNGs are lossless and therefore tend to be much larger for image data which is why JPEGs are used which do not support transparency. Perhaps the new HEIF format will be used in the future that supports both.

Re: Make round card corners with transparency

PostPosted: 15 Aug 2017, 16:29
by Ekkaiaa
Yes, size is like five times more. Optimal is that software uses round corners container when needed (thinks simply in html+css, just border-radius css do the trick) but seems that many ones does not do that, so... that's why I used Imagemagick (for Xmage in this case).

Re: Make round card corners with transparency

PostPosted: 16 Aug 2017, 14:39
by kudit
Yes, most should be able to handle it in CSS or however they're displaying. How are you using it where you can't round the edges?