Episode 052: Clear the Sky!

The ChiemseeDownload the Video!
Download the companion file!
I shot this image on my way to Cakovec from the airplane over the Chiemsee. That is a famous lake in Bavaria. We were already so high in the air that serious haze made the image flat. It’s the one at the bottom of the image in this post.

In this episode I show how to get rid of the haze by using the curves or levels tool. And of course I have a way using layers. A layer copy in burn mode takes a lot of the haze away. Further fine tuning involves a layer mask and an overlay layer copy.

EDIT: Mathias (http://mathias.lindner.de.vu/) pointed me to an error in the layers version. The last overlay layer didn’t work well. I used a copy of the base image – I should have used a copy of the visible image after all the burning. “Edit|Copy Visible” and then “Edit|Paste” and setting the floating layer to a new layer by “Layer|New Layer” would have done the job. This image here is done that way: Chiemsee - final layer version

Now one could start to lighten the cloud shadow in the forrest and water a bit and correct or enhance the vignetting made by the camera….. But this is not bad, considering the image where I started.

I couldn’t record in Croatia, somehow we never got a recording with sound and video. If I am invited to another such event, I’ll buy a strong enough notebook and test the setup before the trip. But aside from this it was fun and I met a lot of interesting people, most of them connected with the Croatian Linux Group “HULK”.

I recommended Akkana Peck‘s book “Beginning GIMP: From Novice to Professional”. It’s the best book about GIMP I have seen up to now. If you buy via Amazon.com, use the link on her site.

You can find the files used in this episode at the usual place.

The TOC

00:19 Takeoff!
04:30 The problem image
05:50 Look at the histogram
06:33 Try adjusting the curves
07:25 Levels tool
08:50 – Manual adjustment
13:53 – Auto adjustment
14:53 – Pick the points
17:50 Curves tool
19:45 Layers
19:53 – Overlay mode
21:12 – Burn mode
23:40 Comparing the images
26:03 Further tweaking
27:02 – reducing the effect using a layer mask
30:29 The End
TOC made by paynekj

Creative Commons License This work is licensed under a
Creative Commons Attribution-Share Alike 2.0 Germany License.

13 thoughts on “Episode 052: Clear the Sky!

  1. Hi Rolf
    I’ve just been watching this episode and you were talking about the Curves screen and only being able to control the gamma with the middle of the curve. This made me wonder whether you have tried changing the Curve Type. All sorts of oddness follows!
    Cheers and thank you
    John

  2. Hi I just discovered your video podcast via itunes last episode, I learned a lot from watching these two recent casts. Keep up the good work.

  3. @ John: I think you did not get it as Rolf wanted to: I far as I understood him he wanted to say that you are able to adjust the curve as you want to with the curves tool. But with the levels tool you can only set the gamma for the middle of the curve.

    Now my note: As I recognized you have been quite confused by the Overlay layer not working as expected and prob. not even improving the image at all. Total agreement :) The problem is that you used a copy of the basic image for this layer – resulting in simply enlightening as you explained before. You should have used a copy of “what you see” instead to get dark parts as well in this layer. After the Burn layers choose Edit -> Copy what you see (I have the German version so look for something similar) and paste this in the new layer that you set to Overlay.
    Apart from this, neat show again! Maybe you can explain how the Burn method works at all?! Looks quite useful if I can understand the background of it…

  4. @John, Mathias is right, I talked at that moment about the levels tool, not the curves tool. With the curves tool you have full control – and switching to the freehand mode can give you quite interesting results. If you tweak the curve not in the middle or with more than one control point (the famous S-curve comes to mind) then you leave the area where “Gamma” makes any sense. And with the levels tool you can only change Gamma.

    @Mathias: You are right with making a “Copy Visible” and using that as the source for the overlay layer. I must have been not really awake while rushing ths show out. ;-) Correction will be in the next episode.

  5. You said that you are not able to finetune the results of the auto button in the levels dialog since the sliders at the top aren’t updated. Actually they are updated, yet not in the “Value” mode but for every channel separately.

  6. Hi!

    I just found out you can also get some quick results for images like this one using the Brightness and Contrast tool.
    It’s easier, but gives you even less control (no gamma).
    Be sure to activate the Histogram first (Dialogs – Histogram), so you can check the dynamic range while you’re moving the sliders. The brightness slider “moves” the histogram left or right, while the contrast slider spreads it starting from the middle. Try to spread it all the way from left to right but do not go too far, because then highlights will get blown out or details in the dark parts will be lost. I think -80 for brightness and +70 for contrast gives a good result for this picture.

  7. The contrast and brightness sliders do the same as moving the black and white point in the curves tool. Another example that all the tools are the same. ;-)

    The Histogram is nice to have around. Thanks for the reminder.

  8. Thanks to Rolf and Mathias for clarifying that for me – so much of this makes my head spin! I **finally** tried adding extra layers for myself, with some success. And I will try what Mathias suggested next time.

  9. Off topic but, would it make sense to have an “open thread” post to the blog, say once a week, wherein Rolf essentially says nothing in particular besides “Anything Goes”. Or is there such a place to make general comments about Gimp and tutorials that would be off topic in the other threads?

  10. I think comment threads on blogs have their own “character” that forums don’t have, so I think what you have is a good (better) thing. And you do a great job with the video tutorials, so IMHO you should not consume your time with too much extra work.

  11. Nice tutorial, I agree with Rolf that Akkana Peck’s book is a very good one; bought it a few months ago, is great. She devotes a chapter to play with layers to improve images, much in the way Rolf does in the webcast.

    She does encourage readers to try thins by themselves, by now I have already spent my time doing so, and results are often good.

  12. Pingback: MTG: Обзоры выпусков за весь 2008 год! « Блог фотолюбителя :)

Anything to add from your side of the computer?