In Linux, the easiest way to process images is using imagemagick. It is a command line program you can use to manipulate images very quickly. With it, you can scale images, adjust proportions, add watermarks and alot lot more.

These days, with photos from your camera tpyically of the order of 1.2 – 2.5MB in size, uploading them to the internet in bulk is the stuff of dreams, so better to scale them all down and then upload. Here’s how.

Step 1. Install imagemagick.

Open a terminal window using CTRL + ALT + T

Now, install imagemagik..

sudo apt-get install imagemagik

Now let’s try some examples…

First off, copy the photos you want to modify to a new folder, so you have the originals intact, otheriwse you will modify the originals. Bad idea.

We’ll call this folder /home/darth/pics in these examples.

Reduce the photo called hoth.jpg by 50%

mogrify -resize 50% /home/darth/pics/hoth.jpg

Scale the image to be 1024 pixels wide and whatever number of pixels high, scaled in proportion…

mogrify -resize 1024x /home/darth/pics/hoth.jpg

Scale the image to be 500 pixels high and whatever number of pixels wide, scaled in proportion…

mogrify -resize x500 /home/darth/pics/hoth.jpg

Strip the image of all exif data, so remove make and model of camera, GPS data, flash, shutter and aperture speed, etc. etc.

mogrify -strip /home/darth/pics/hoth.jpg

Do the whole freakin’ folder! (Rotate the photos as required, reize them to be 1024 pixels across the top and do that for all jpegs in the folders and subfolders in /home/darth/pics/deathstar

mogrify --auto-orient -strip -resize 1024x /home/darth/pics/deathstar/*/*.JPG

There are a bajillion more possibilities and commands and options in the suite. Check it out. http://www.imagemagick.org/script/command-line-tools.php