I cover image processing in the second half of my book, yet I wanted to know whether it was possible to edit an image without installing any software.

Although I have readers use free software in the book, I wanted to get to the point where you didn’t have to install anything at all.

The good news is that I was able to do it – I found a way to process images completely online. You can combine RGB FITS images into a final image and export it in multiple formats. That’s the good news.

The bad news is that the quality of the final image is not as good as you can get it using software like MaxIM DL and Photoshop (or whatever software you use).

The processing options are limited and you cannot do things like stack images and you cannot use any luminance images. This technique is good for quickly producing a color image if all you’re looking for is a color image.

Update November 2019: This article was originally published in August 2019. Since then, I have found a way to include luminance data into your images when processing images completely online. Slooh.com members, please check out this article: Using Slooh.com’s JS9 FITS Editor To Create RGB Images

If you’re looking for the best possible image, you need to buy, install, and learn to use some software.

I’ll discuss this approach in more detail in a series of blog posts.

Here are the results.

This is the final image that was created using online tools only (right from the FITS file to the final JPG):

And here’s the final image processed using MaxIM DL and Photoshop:

It might be difficult to see here because the images are small; however, there’s much more detail in the second image.

The image, by the way, is of Stephan’s Quintet and the FITS files are from the Sloan Digital Sky Survey’s site. For reference, this is the original image from SDSS:

Of course, the image is of amazing quality even though it is compressed here quite a bit. It goes to show you how much work the SDSS puts into their images.

Here are the articles in this series: