Welcome to NASA’s Astrophoto Challenge!

First, we’ll take you through the steps of using our JS9-4L image processing tool.

Then you can process your own astronomical images, which you can submit to NASA’s Astrophoto Challenge.

Select an Image

Start by opening a sample image file to practice using JS9-4L. Click on any of the Andromeda Galaxy or Cartwheel Galaxy images.

Adjust the Scale

Use these scales to highlight different regions of relative brightness in your image. Log scale works best for dim images.

Switch between the scales to see how regions that appear black suddenly reveal much greater detail.

Adjust the Controls

Use these sliders to fine-tune the contrast.

Pixel values below the Low Brightness Limit will be absolute black, values above the High Brightness Limit will be absolute white.

Advanced Controls

The Contrast and Bias sliders are advanced tools that allow you to stretch, squish and shift the pixel value range in which your colors are displayed.

Play with them as you like to enhance your image!

Adjust the Color

Choose from this list of colormaps to either
add beauty to your image, or highlight the
relative brightness of different regions in your image.

You can also make real-color images with
RGB mode, but you ought to watch a tutorial
on creating RGB images first.

Auto Align Images

When you want to blend multiple images, you probably want to use the Auto Align Images tool. This will pan, rotate, and zoom all open images so they line up. Note that Andromeda and Cartwheel are in different parts of the sky, so aligning them with each other will not work.

Watch the tutorials on how to auto-align images and also how to blend images to learn more.

Save Your Image

When you’re done, don’t forget to save your image to your computer or device! You’ll need it when you submit your image to the Astrophoto Challenge.


And make sure to choose either PNG or JPEG format. (FITS format won’t save all the processing that you’ve done.)

Close the Image

At this point you know the main steps of processing images in JS9-4L, so you don’t need the image that you opened at the beginning.

You can close any image by clicking the × next to the image filename in the My List dropdown.

**You can open your own image by using the Image dropdown**

Explore More

If you want more detailed help, Video Tutorials will take you to a collection of tutorials on processing images.

To learn more about what these images mean, Hear from Experts opens a video by astronomy experts introducing you to galaxies and their interactions.

You’re All Set!

But if you would like to watch this Guided Tour again, just click “Replay Guided Tour” below.