You too can make your own full-colour, high-resolution, deep-space images, just like the Tulip nebula mega-mosaic below – and you don’t even need to own a telescope.
However, you do need a copy of Photoshop and a copy of Noel Carboni’s Astronomy Actions for Photoshop.
The first thing you need to do is get your hands on the data which you will process into a full-colour image – I have described this process in an earlier Astronomy Now article – so if you are an Astronomy Now subscriber, look the process up there.
You will grab the data from the SkyView Query Form site. Put in the co-ordinates of the object you want a picture of (or the object name) in the box at the top. Go down to where it says what datasets are available and click on DSS2 red AND blue data. Where it asks for image quality data put in 6000 pixels and leave the rest unchecked – this will give you a 6000 x 6000 pixel image at the highest spatial resolution on offer. Send off the query and it will download the images to your monitor. Go to the bottom of each image and click download the FITS files. You will now have the red and blue channel data for your chosen object. Now we need to process the data.
Open up Photoshop – and in Noel’s actions click on “Construct RGB image from channel files”. This process expects you to supply red, green and blue channel data – but as you only have red and blue channel data you need to put the blue channel data into the green channel when the program asks you for it. Go through the construct RGB process and at the end you will have a colour image of your object – but in the wrong colours as you didn’t provide any green channel data – fear not – Noel’s actions will come to the rescue! Now click on “Synthesise Green Channel from Red and Blue” and Noel’s Actions will create an artificial green channel for your image giving something that looks a bit closer to “real” colour.
Now all you need to do is tweak the image in Photoshop to get something closer to what you are looking for. I actually take the image into Paint Shop Pro at this point as it has a couple of very powerful “one click” processes. I use the contrast enhancement tool on Darker/Normal/Normal and the saturation enhancement tool on More Colour/Normal – to get the image looking more how I want it – I then take it back into Photoshop for further cleaning up and to put on any (Noel Carboni) star spikes if I feel they are appropriate.
And that’s it. You can produce deep-sky images of a quality far better than you can grab from your back garden with mega-expensive kit, and do it in far less time than it would take you to get just the data. Makes you wonder why we actually bother to do it the hard way!
