Anyone want to take a shot at a .tif?

[ubertank]

As processing can be such a lonely exercise, I thought it would be really helpful to see what (if anything) someone could get out of a .tif file in PS or GIMP so I can see what an image is capable of under the right processing skills.

The trouble when you've got nobody alongside you with more experience, is that it's really easy to just blame the setup/focus/exposures etc.. as you have no idea what detail can be extracted from an image.

If anyone would like a crack at it, I'd be really appreciative and interested. Here's M51 from last night. Stacked in DSS. 10x60 sec subs through an ED80 and 1100D with ten darks. Not the longest exposure for this sort of target I'm sure, but if anyone fancies a go I'd be really interested nonetheless.

An Astronomik CLD filter was used so it'll be a little blue.

http://dropcanvas.com/n7f23/1

The image will seem really dark but M51 is in there towards the bottom, just left of the middle.

[Leveye]

I'm not able to download a file that PS can open with what you're using.

[ubertank]

Really? I just went to the link I provided, clicked "download" on the top right and it's downloaded the .tif file for me which I've opened in PS.

Did you do that or did you try some other way?

[Ouroboros]

Download worked for me and it opened in PS.

You did click the link and then click the download button on the page that opens?

[gkec]

Just to say I downloaded the file and opened it in Canon Digital Photo Professional but couldn't see M51. Doesn't mean it is not there but I could open the file.

[ubertank]

2/3 of the way down, just left of centre. Looks like two stars in zoomed, but when zoomed in and the of curve adjusted slightly is quite clear with spiral arms.

Not an amazing image at all, but I'm just curious what people with the know how can do with an image like that.

[Ouroboros]

Ubertank - I was imaging M51 last night too

I just had a quick go at tweaking your image in photoshop. I had no luck colour balancing the image from the green introduced by the Astronomic filter. I have had the same problem when I have used such a filter. In fact I gave up using it after a while I was so disappointed with the results.

So I will be very interested to see if the experienced Image processors get better results and how they do it.

[Ouroboros]

Incidentally I could clearly see the galaxy once I'd changed the levels. I even made a reasonable stab at removing the background green. But couldn't rebalance the galaxy itself from looking ... Well ... Green.

[PorkyB]

The best I could do is this.

The problem is that there is so little data there to start with it will always look over-stretched. I am assuming that you only removed the bare minimum with levels to remove the backgound noise.

The CLS filter doesn't introduce any blue or green into the image. The apparent shift towards cyan is purely due to the removal of so much orange. I use the Hue-Saturation feature in GIMP to move the cyan back to something more neutral.

[Ouroboros]

True. The filter 'removes' red. It doesn't 'introduce' green.

Am I right in thinking that these filters are less useful with modern street lighting as it provides more spectrally neutral illumination than the traditional sodium only lighting?

Ive only ever usefully used such a filter to produce monochrome images of very faint objects that would have otherwise been swamped by light pollution.

[PorkyB]

Am I right in thinking that these filters are less useful with modern street lighting

I am working on the basis that in a city the size of Birmingham there will be lots of old-style lighting around for a good many years to come. While new developments and renewal projects are installing LED lighting, I don't think our cash-strapped council will be doing a large-scale replacement programme any time soon.

[Shibby]

Here's what I've pulled out with a quick mess around in PS. It's very promising I would say, nice focus and star shapes! More subs would certainly help reduce the noise; grab as many as you can! With enough, you won't necessarily need the darks which actually increase the noise if you don't have enough of them.

[ubertank]

Here's what I've pulled out with a quick mess around in PS. It's very promising I would say, nice focus and star shapes! More subs would certainly help reduce the noise; grab as many as you can! With enough, you won't necessarily need the darks which actually increase the noise if you don't have enough of them.

Wow Shibby well done. Considering the low quality of the .tif that's pretty impressive.

Thanks ever so much to everyone who had a go at editing. It's really encouraging to get an idea of what quality can be obtained from particular images. When you're working blind as it were, there's a temptation to say to yourself that the images are no good when they obviously aren't as bad as you think.

This has been really helpful.

Can I ask what tweaks you made to get that sort of quality Shibby?

[x6gas]

Here's my attempt...

A lot of processing to control the noise but I have also lost some of the detail...

[ubertank]

Another really amazing job.

Considering this image was generated from 10 x 60 second exposures at 800ISO, I'd love to see what you could with more, longer exposures and a higher ISO.

I had thought the image was next to worthless to be honest. The importance of processing just can't be overstated.

[Ouroboros]

Here's my attempt...

A lot of processing to control the noise but I have also lost some of the detail...

Good. How did you get rid of the noisy background and produce such a dark sky?

I see whatever you have done has also changed the colour balance of the galaxy which now looks yellow. Is there a way to shift your image now to a more naturalistic colour balance. Add more blue?

[Steve Ward]

My clumsy effort in Photo+X5 after a tinker with the adjustments in DSS ,

Various small steps in Levels , Curves , etc.

[x6gas]

Good. How did you get rid of the noisy background and produce such a dark sky?

I used the layer mask technique in Photoshop. Basically you create a duplicate layer, add a layer mask and paste the image into the layer mask, apply a levels adjustment to the mask in order to emphasize the stars and the galaxy (so the background sky in the mask should be white, the stars and galaxy black). Then a lavel adjustment on the duplicate layer only effects the background so you can darken it. I applied a colour noise reduction followed by a guassian blur in the same way to sort the sky out...

I see whatever you have done has also changed the colour balance of the galaxy which now looks yellow. Is there a way to shift your image now to a more naturalistic colour balance. Add more blue?

Of course. I'd changed the hue and then applied selective colour adjustmants but you can make it whatever colour you want; I'd just tried to put back the lost orange...

Actually I think I prefer it in black and white as there is so little colour data preserved (it's all blue!)