Questions[image-processing](ubuntu)

You can compare two text files very easy with diff and even better with meld:

If you use diff for images, you get an example like this:

$ diff zivi-besch.tif zivildienst.tif 
Binary files zivi-besch.tif and zivildienst.tif differ

Here is an example:

Original from http://commons.wikimedia.org/wiki/File:Tux.svg

Edited:

I've added a white background to both images and applied GIMPs "Difference" filter to get this:

It is a very simple method how a diff could work, but I can imagine much better (and more complicated) ones.

Do you know a program which works for images like meld does for texts?

(If a program existed that could give a percentage (0% the same image - 100% the same image) I would also be interested in it, but I am looking for one that gives me visual hints where differences are.)

I want to scale all images in a given folder to the same width (but different appropriately scaled heights). How can I do this using a GUI-based or command-line tool?

For bonus points, is it possible to restrict which images are scaled based on their initial width (that is, only scale images that have a width > x and/or a width < y)?

I'm trying to mass convert a handful of .tif files. I found phatch could look like a good candidiate but I'm running Ubuntu 11.04. Looks like they don't have a .deb for my version.

Anyone have any alternatives to phatch or any other recommendations as to quickly batch convert tif to jpeg files.

I'm looking for a non-Photoshop (ala Wine) solution.

Often I need to annotate (draw some arrows, lines, basic shapes like squares, ellipses etc and enter some text) on top of pictures (JPG, PNG images) and screenshots (again png images). I would also need to be able to crop, resize etc.

I tried the Gimp but I could only enter text and perform all image transformations but couldn't find a way to draw boxes etc.

I finally settled to Openoffice.org draw, but I know that isn't what I want, because in oodraw I need to insert my pic into a drawing and resize it (or the drawing) to fit and then go about making changes and finally export to png...

Is there any image editor that allows adding shapes and text to jpg & png files and save the modified file in its place? If the tool can also have template collections (like dia does) for shapes that is an added bonus.

I would like to know how to resize images in Ubuntu. What is the easiest tool to do so?