[PLUG] Resizing images with imagemagick

[Ben Koenig]

On 4/23/19 12:30 PM, Rich Shepard wrote:
> On Tue, 23 Apr 2019, Ali Corbin wrote:
>
>> It'll take human intervention, to look at each individual image and 
>> decide
>> whether to rotate it.
>
> Ali,
>
> This I knew. I usually use the GIMP for this manipulation and am glad to
> learn that ...
>
>> Happily, it's not too onerous to do this in imagemagick, using the
>> 'display' command.
>>
>> This will bring up the first jpg in the directory as the start of a
>> slideshow.
>> display *.jpg &
>>
>> Then you can hit the space bar to cycle through the images. '/' or '\'
>> will rotate the image that you're looking at, and Ctrl-S will save it.
>
> And once they're all properly oriented I can use convert's -resize 
> option to
> change all in the same subdirectory.
>
> Much appreciated,
>
> Rich
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BTW, the identify tool does this. It's part of IM as are a number of 
other image processing commands.


Get the size of the image using

$ identify -format "%wx%h\n" /path/to/image


in the -format string

%w is the pixel width

%h is the height

\n is to print a newline, otherwise it clobbers your prompt.


Without -format it prints out a lot of stuff, see 
https://www.imagemagick.org/script/escape.php for more options in 
trimming the output of identify.


Once you have an identify command that is scriptable, a BASH becomes trivial

------

$aspectratio = identify $image

IF [ $aspectratio is wrong ]; THEN

   convert $image $newaspectratio

   convert $image $newscale

ELSE

   convert $image $newscale

FI

------

Just pounding out pseudocode so that we are aware that YES, imagemagick 
can do this for you.