With everything so expensive these days, I like to look around before I buy. Unfortunately, it is a truism that you get what you pay for. Thankfully, there are (rare) exceptions. One such exception is to be found in the realm of software. What with the open source movement and loads of really great astronomer /programmers out there, there's little need to spend lots of money to get your hands on decent software.

I spend quite a bit of time manipulating images of various sorts. There are a number of wonderful tools out there, most quite expensive (Photoshop). The cheaper ones tend to fall far short of my requirements. Not so with The GIMP! The GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software suitable for such tasks as photo retouching, image composition and image authoring. There's not much it can't do. Available for Linux and Windows, I don't have to learn to use a new package when I swop from one to the other.

Find it at http://www.gimp.org/

ImageTool is a free image processing and analysis program for Windows. It can acquire, display, edit, analyze, process, compress, save and print gray scale and color images.IT can read and write over 22 common file formats including BMP, PCX, TIF, GIF and JPEG. Image analysis functions include dimensional (distance, angle, perimeter, area) and gray scale measurements (point, line and area histogram with statistics). ImageTool supports standard image processing functions such as contrast manipulation, sharpening, smoothing, edge detection, median filtering and spatial convolutions with user-defined convolution masks.

http://ddsdx.uthscsa.edu/dig/itdesc.html

AstroStack is a freeware program that takes a series of images (the "stack") and combines them into one. The resulting image will be more detailed and noisefree. It was written with astronomical purposes in mind, but is also being used in fields like microscopy and optometry. The first version of AstroStack has enthusiastic users. They have given a lot of useful suggestions for improvement.

http://www.astrostack.com

If you're serious about working with astronomical images, you have to have a FITS viewer and manipulation application. FITS stands for `Flexible Image Transport System' and is the standard astronomical data format endorsed by both NASA and the IAU. FITS is much more than an image format (such as JPG or GIF) and is primarily designed to store scientific data sets consisting of multi-dimensional arrays (1-D spectra, 2-D images or 3-D data cubes) and 2-dimensional tables containing rows and columns of data.

Avis is a freeware FITS viewer for Windows 95, 98 and NT. FITS files are used in scientific applications like astronomy and medical imaging.

http://www.sira.it/msb/avis.htm

The FITSview family consists of viewers for astronomical images in FITS format. Viewers are available for MS-Windows, Macintosh and Unix systems and offer a wide variety of image display features . The FITSview programs are distributed free of charge by the (USA) National Radio Astronomy Observatory.

http://www.nrao.edu/software/fitsview/

CADET is basically a program for calibration and deconvolution of astronomical images in FITS and BMP formats

http://www.terra.es/personal2/oscarcj/introeng.htm

SAOImage DS9 is an astronomical imaging and data visualization application. DS9 supports FITS images and binary tables, multiple frame buffers, region manipulation, and many scale algorithms and colormaps. It provides for easy communication with external analysis tasks and is highly configurable and extensible

http://hea-www.harvard.edu/RD/ds9/

AstroByte Logging Software is a database system designed to help you keep all of your viewing sessions documented. It also produces report logs, and reports to assist in the field.

http://www.mainbyte.com/astrobyte/

Finally, here are a few ATM sites to add to your favourites. The last one has an interesting plan for a 22" reflector and a 12.5" pair of bins.