Projetos do DR5
     - Diagrama de Hubble
     - Cor
     - Tipos Espectrais
     - Diagrama H-R
     - Galáxias
     - Mapeamentos do Céu
     - Quasares
     - Processamento de Imagem
 Para Crianças
 Jogos e Competições
 Links para Outros
Image Processing
 What is an Image?
 Retrieving Images
 Analyzing Images
 Tricolor Images
 Other Images
 Other Features
 Alternate Views
     - Challenges
 Your Results


You have seen a few of the features of a good introductory image processing program. There are many more complex modifications you can make to the images. For example, you can apply a variety of filters to the image. The filters use mathematical algorithms to modify the image. Some filters are easy to use, while others require a great deal of technical knowledge. The software also will calculate the ra, dec, and magnitude of all objects in the field if you have a star catalog such as the Hubble Guide Star Catalog (although this feature requires the purchase of an additional CD-ROM).

The standard tricolor images produced by the SDSS are very good images. If you are looking for something specific, you can frequently make a picture that brings out other details. The "best" picture is a very relative term. A picture that is processed to show faint asteroids may be useless to study the bright core of a galaxy in the same field.

Research Challenges

Try one or more of the following exercises. When you finish them, E-mail us your images and interpretations. We'll look at all the results we receive, and we'll put the best of them up on these pages!

Research Challenge 1. Search for an object that is in both the SDSS database and the 2MASS database. Retrieve the images from 2MASS and the SDSS. Make a tri-color image using the J, H, or K filters for 2MASS data and filters of your choice for SDSS data. Compare and contrast your images. What information do they give you about the object? What interpretations can you make by studying the two images?

Research Challenge 2. Scientists are very interested in distant quasars, objects that have very red colors. Retrieve the i and z images for a field. Use the blink command to look for objects that are visible in the z filter but not visible in the i filter. These objects might be distant quasars or very small, cool stars. Either way, you will be finding something very interesting!

Look at these objects in detail, using these or other images. What can you conclude about them? How could you tell if one of these objects were a quasar or a cool star?

Research Challenge 3. Iris can obtain images from a webcam. If you have access to a webcam and a small telescope, mount the webcam looking into the eyepiece. Click on the Webcam menu in Iris and click Image Acquisition. Obtain and process an image of a bright object such as a moon or a planet. Although you cannot see very faint objects with a webcam, many amateur astronomers produce nice images of bright objects using webcams.