Image Processing Basics

Color Imaging

Most astronomical CCD cameras create color images by combining black and white images taken through red, green, and blue filters.  In theBasics of Taking CCD Images section we gave the example of the Trifid Nebula, M20, imaged using this technique.  We ended up with three image files, one for each color.  After processing these images… More »

Image Processing Filters

A filter is an image processing routine applied to an image to enhance details.  This is usually done in one of two ways:  by smoothing the image to remove noise and show subtle features hidden by the noise, or by sharpening the image to reveal more fine details.  For now we will look at the… More »

Image Display

The most basic processing step after image calibration is simply altering the way in which the image is displayed so it looks best on your computer screen.  Computer screens are limited to displaying 256 shades of grey.  This is all that is necessary to produce images which look pleasing to the human eye.  The number… More »

Image Calibration

Below are the basic steps involved in CCD image calibration.  For step-by-step instructions with specific software packages, see the Software Instructions section. Getting Started The first thing that must be done to a raw CCD image is calibration.  This is where the dark frames you took along with your images come into play.  There are… More »

Image Processing Basics

So, you have taken your first CCD images and they look pretty good, but you are ready to improve them.  Image processing allows you to enhance CCD images using a wide variety of algorithms.  However, keep in mind that image processing can enhance a good picture, but it cannot make a bad picture good.  It… More »