Some image magic

[viking60]

Install imagemagic it is in your repos (most likely you have it installed already). Now you can use the Command Line Interface to rapidly do some magic to your images. Yes you can do it with programs like Gimp too but it takes a lot more time. So let us look at some practical examples. You have this avatar that you use in forums but this new forum demands it to be max 100x100 pixels. You need to adjust that humongus Wallpaper that is way to big. Or you want a series of images to be exactly the same size for your animation.

Why do we need a post here for that it can all be found here?
Well sometimes it is hard to find obvious stuff when you have all those fantastic functions to describe Here is an example:
If I did a correct resize to my resolution of 1366x768:

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convert bakgrunn.png -resize 1366x768 newwp.png


It would get either 1366 or 768 right but not both! I am sure it has something to do with the original proportions of the image.
So to get it right you must do it like this:

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convert bakgrunn.png -resize 1366x768! newwp.png


The difference is the
Now the newwp.png will be exactly 1366x768 not 970x768 or whatever

This is very useful for avatars also.
To resize all your jpg images in a directory to 50% you can use wildcards

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convert *.jpg -resize 50% smaller.jpg


You have to provide a name for the new sized images but they will be numbered like this.
smaller-0.jpg smaller-1.jpg etc.

So if you want to convert all your jpg images in a directory to exactly 200x200 pixels and convert them to png you could do it like this:

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convert *.jpg -resize 200x200! 200.png


You would then get a series of images called 200-0.png 200-1.png 200-2.png etc.

So now you can make all the wallpapers in your Wallpaper directory the same correct size in one sec.

[rolf]

Yes, that's very useful for certain situations and I saw that in your wallpaper tip.
I like fotoxx for a graphical program that is very full-featured and intuitive to do quick resizing, cropping, etc. Have you tried it?

[viking60]

Not yet - Trying now.......Ill get back to it when I am through with the imagemagic.

[viking60]

If your Wallpaper is rather dull and you want to give it that quality feel try this:

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convert MyWallpaper.jpeg -pointsize 100 -font Impact -fill cyan -gravity South  -draw "text 25,40 'Berserk power'"  output.png

It will write text on the "South" of your wall paper you can change it to North etc, pointsize 100 is the font size and Impact is the font play around with it....
And pick a real wallpaper in stead of MyWallpaper.jpeg it will create the modified wallpaper under output.png.
The text will be added to the picture like this:


To rotate an image

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convert MyWallpaper.png -rotate 180 output.png

Comes in handy when you discover that you held the camera upside down...


If you do not want to keep the original and want to change the image directly you can write the changes back to the same image;

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convert output.png -rotate 180 output.png


For brave Berserks who laugh in the face of backups only...

To resize the images themselves instead of writing the changes to a new file you can use mogrify

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mogrify -resize 50% *.jpg


This will reduce the size of all jpg files in the directory.

[viking60]

Many think it is cleaner to put the source image and the output image at the end:

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convert -pointsize 10 -font Impact -fill cyan -gravity North  -draw "text 1,30 'Berserk power'"  guru.png output.png


here is the output

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convert -pointsize 12 -font Arial -fill yellow -gravity North  -draw "text 1,30 'Guru'"  guru.png output.png

But this is a bit small so I did a:

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convert -resize 200%  output.png output2.png

This is output2.png

[viking60]

Tried fotoxx but it keeps chrashing in Mandriva....
Also there seems to be a problem for Mandriva (2010.2) to add the selected fonts when using imagemagic. This Bug says it is fixed but I wonder
In any case Mandriva just picks a default font so it does work (kind of).

[rolf]

Looking through some of the various manuals in imagemagick-6.7.0.9-1.2-mdv2011.0.x86_64, I see that it has a lot of features, suitable for scripting, for example, on a website. However, while I can intuit that the 'North' switch would put the text toward the top of the output, I wonder if how far 'North' and left-right-centered is somehow automatic or specified by the '1,30' part.

Anyway, I tried the montage command with 9 same-sized gifs

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[rolf@localhost montage]$ montage icon* -adjoin montage.gif

A squared whole number of square, same-sized icons fit nicely into a square array, a bit vanilla but I'm lazy to explore the vast capabilities of ImageMagick.

Trying an equal number of animated gifs, differing geometries:

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[rolf@localhost montage]$ montage *gif -adjoin montage2.gif

Well, it didn't montage the animation but, it seems, all the layers of the gifs. I'm sure there are many practical uses for ImageMagick, nonethless.

Sad about fotoxx crashing. I think I remember having some problem with it but not what or how fixed, if so. If you ran it from a prompt, maybe a message would point the way. Here, ftp://mirror.yandex.ru/mandriva/officia ... x86_64.rpm seems to be working ok.

[viking60]

However, while I can intuit that the 'North' switch would put the text toward the top of the output, I wonder if how far 'North' and left-right-centered is somehow automatic or specified by the '1,30' part.

Yes the North is a gravity thing pulling it to the top of the pic. And the 1,30 part are the XY coordinates so they are more spesific. I am not sure how they interact. But you can remove the gravity alltogether and use only XY.
Or you can set the draw to zero:

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-draw "text 0,0 'Über Berserks rule'"

and then you will get the full and predictable effect of North South and NortWest or whatever in your gravity settings.
Like this

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convert -pointsize 14 -gravity North -font Lucida -fill Brown   -draw "text 0,0 'Über'"  viking.png output.png

I only use the xy coordinates to place it more exactly (on the helmet) by error and trial:

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convert -pointsize 14 -gravity North -font Lucida -fill Brown   -draw "text 1,10 'Ûber'"  viking.png output.png


And I think you can animate your gifs again with the animate command:
http://www.imagemagick.org/script/animate.php

[rolf]

So, it looks like 'North, South, East, West' are already centered wrt their respective orthogonal property. If so, wouldn't '0,30' be the setting to keep that 'North' text centered on the x-axis?

[viking60]

Jup that sounds about right North and South are centered.
I stay on the "10" line and I can adjust (from center) with say 5,10 to the right or even with a negative no -5,10 to the left. Or I move up or down by changing "10" to say 30 which would put the text lower (to the South)
This should make it clear:

What I have used here is the animate command. I put all the vikings above in a directory and ran:

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animate *.jpg

This starts an animation only to show that it works you can rightclick and save. That will give you a series of images . no animation.
So we have to use convert here too:

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convert -delay 30 berserk-0 berserk-1 berserk-2 berserk-3 berserk-4 berserk-5 -loop 0 playme.gif

[viking60]

Same animation as above with different delay

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convert -delay 100 berserk-0 berserk-1 berserk-2 berserk-3 berserk-4 berserk-5 -loop 0 playme.gif

[viking60]

Ok time for some frames:
To raise your image:

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convert -raise 7x7 viking60.png vikingraised.png

And for a lower frame:

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convert +raise 7x7 viking60.png vikinglowered.png

Now I am officially framed....