Peter Mac And Associates» Uncategorized

Scaling images in batch mode

peter — Tue, 24 Aug 2010 07:23:15 +0000

I have lots of folders with images uploaded from digital cameras. Average image size is 3MB which is way too large for uploading to web based image sites. What I need to do is to rescale the images but doing them one at a time is a pain so I wrote a little script to do them one folder at a time.

The script makes use of a program called ‘convert’. This is part of the ImageMagick suite of tools.

Install ImageMagick

sudo apt-get install imagemagick

Once installed try to verify the location of the convert program

which convert
convert is /usr/bin/convert

The way the script works is to create a new folder called ‘resized’ under the folder you want to process. It then places rescaled versions of the images it finds in the source folder.

The scaling is performed by passing a width x height parameter to the convert program. The question is how do you know what value to provide without screwing up the ratio of your image. What I do is open a sample image in Gimp. Go to the ‘Image|Scale’ menu option. I pick a value for the width, hit tab and it provides you with the correct value for the height. This is fine if all your images are of the same size. You’ll have to put in a bit of work if they are different sizes.

Here’s the script..it’s really simple as you can see, but I had an itch and I had to scratch it.

#!/bin/bash

convert_command=/usr/bin/convert
#get the folder name to be procesed
if [ $# -ne 2 ]
then
echo "Error in $0 - Invalid number of arguments."
echo "Syntax: $0 "
echo "Example $0 ./images 1024x680"
exit 1
fi
folder=$1
newsize=$2
resized="resized"
resized_dir="$1/$resized"

echo "Resized images will be placed into the folder $resized"
if [ ! -d $resized_dir ]
then
mkdir $resized_dir
fi
cd $folder
for file in $( ls . )
do
if [ -f $file ]
then
echo "Processing $file..."
convert -resize $newsize $file "$resized/$file"
fi

done

Save the script as image_resize.sh. Do a chmod a+x so you can execute it. Then create a sample folder with a few images copied just for testing. Run it as follows:

./image_resize.sh path/to/images 1024x680

That’s all folks!

Public Key

peter — Wed, 15 Oct 2008 02:23:59 +0000

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Click here to download this as key as a file

Purrfect Java Solutions

peter — Sun, 05 Aug 2007 04:17:32 +0000

Meet “Java”, a new addition to the PeterMac team.

Although only 9 weeks old, she shows great focus in object oriented design (she chases any object that moves). She’s got an excellent grasp of string manipulation technniques and we have to agree that her display of experience in the J2SE (Sleeping and Eating) area is beyond expectations for one so young.

Minister for misCommunication

peter — Tue, 22 Aug 2006 22:21:27 +0000

A recent brain-fart by the Australian Minister for Communications, Helen Coonan, has exemplefied why Australia remains a relative technology backwater. She said that she expects people ought to be happy with existing Internet speeds.

“Well they ought to be in Sydney, Melbourne, Adelaide, Brisbane, certainly and Perth,” she said.

“They should be reasonably happy with their speed of broadband, if they have ADSL 2 Plus.

“There are nine providers that already provide these speeds.”

This outburst happened as a result of an announcement by Telstra (the 51% government owned body responsible for maintaining the telecomms infrastructure) that it was pulling out of a proposed fibre optic upgrade to existing networks.

Indeed there is access to ADSL 2+ in these cities but no thanks to Government support. The roll-out has been excruciatingly slow and is only available in higher population density areas. It (the ADSL2 network)has been taken on by a consortium of private companies with the previous threat of the Telstra upgrade having the potential to render their effort futile.

For a Minister of Communications to make such a generalised and uninformed comment smacks of a level of ignorance that can only come from some-one whos’ tenure in the role is transient. Be warned, your communications minister does not have the best interests of Australian Internet users at heart.

Statistics from the OECD show Australia in 18^th place in terms of broadband take-up. Although this is not a reflection of Internet speeds, it is a reflection on the perceived cost/benefit available to Australian consumers. Get your act together Minister!

For more information check out this article by the Australian Broadcasting Corporation