Episode 163: Colour Curves

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Years ago I bought a used Peleng Fisheye and never used it much. So I took it for a walk and shot some scenes here in Berlin. At the top is an image of the famous TV tower at the Alexanderplatz.

After a bit of ramblings about Fisheye lenses I process a shot from a hall in the subway station below the Alexanderplatz. There I use the curve tool to get the colours “right”. Not “right” as in “true to reality” but as in “the right atmosphere”. Tweaking the red, green and blue colour channels can change an image quite a lot.

Never stack curve operations – do it in one step. A little experiment shows the result of not following that advice. A nice recall feature in the curves dialog allows it to reload the last curves. In case of an error just Undo and tweak your curve.

I am absolutely not sure how to sharpen the image. Help me in the forum!

The TOC

00:30 Peleng Fisheye Lens
05:00 Image loaded in GIMP
05:10 Rotating and cropping
06:15 GIMP 2.7.3 remebers the window settings!
06:30 Rotate tool in corrective mode
07:42 Inside out crop
09:20 Copy the layer for backup
09:30 Contrast correction with the curves tool
10:20 A click to early
10:30 Curve operations are stored – easily redone
10:50 RGB colour channels
11:00 Reducing a red colour cast
12:00 Undo changes – not with “Reset”
12:20 Change blue and green in the shadows
14:00 Experiment: One curve operation vs. a series of
16:00 Sharpening the image
17:00 Saving the image
17:30 The Meet the GIMP Forum
18:50 The End

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Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.

Episode 139: Flight Cancelled!

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Finally there is a new show! This time I tackle an image shot at the airport here in Bremen. Before that I tell a bit about the dangers of being a teacher, an online paint program written in HTML5, content aware fill in TheOtherProgram and my new job in Berlin. I am looking for a flat there, by the way.

The image from the Hamburg train station I had planed to process turned out to be marred by motion blurr. A short discussion about how to avoid this is in the show – I hope I recall this next time.

Oh, and I’ll be in England the first week of May 2010. I may have time for a meeting in central London on May 6th – Election Day. Depends on how the kids behave. 😉 More on twitter.

The TOC

00:20 Greetings and looking for a flat in Berlin
03:30 Content aware Fill in Photoshop – http://photowalkthrough.com
04:20 HTML5 graphics program
05:30 Train Station image and motion blurr
08:10 Baggage claimage area shot
08:50 Intentions of the image
09:40 Straighten the image
11:30 Finding a crop
14:30 First try: enhance contrast and colours
16:00 Using curves for reducing contrast
21:40 Selective sharpening
24:00 Function of a layer mask
25:00 Denoise the layer mask
26:30 Sharpen the top layer
31:00 Saving as XCF for further work
32:00 Rolf is in England next week – http://twitter.com/rstein

The companion file contains the original shot in JPG and NEF and the XCF file in its present state. Still work to do. And I put the train station image in there too, perhaps somebody wants to play with it.

Creative Commons License
Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.

Episode 094: Wine and Curves

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94

It’s curves time again. This powerful tool is in the centre of the stage and I try to explain it’s nearly unlimited power over colours, contrasts and brightness. Worth to learn.

This week I visit a vineyard in Missouri (too bad – only via HTTP) and discuss the dangers of blowing out the highlights under overcast sky. Just underexpose a bit when in doubt, you can get detail out of dark areas but 255 white has nothing to save in it.

The overexposed sky has killed all the details in a tree that looked over the horizon. I use the curves tool on a layer copy to get the details back and integrate the fixed tree with a layer mask into the original shot.

Then I adjust the black and white points and give a little more contrast to the image – of course with the curves tool. Finally I have some fun with – of course – the curves tool and come to an image that is not suitable for a vineyard but for a LSD factory. But they don’t have websites….

The TOC

(Kevin, I made one! 🙂 )

00:20 Wine, Missouri and the Church
02:50 One image – two views
04:30 The histogram
06:40 Diagnosing overexposure
07:30 DO NOT BLOW OUT THE HIGHLIGHTS!!!
09:25 Histogram details
09:40 Linear and logarithmic
13:50 Blown out tree branches
14:30 Curves tool sight seeing
15:10 The translation line/curve
15:40 Black point
17:50 Set contrast in the curve
18:40 Bend the curve
20:30 Inspector – eye dropper
22:30 Repairing the tree
25:30 Get the blue cast out of the twigs
25:40 Adding a layer mask
29:30 Copy visible in new layer
33:00 “HDR” in a very cheap way
34:30 Power of the curve

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Episode 042: Don’t Panic!

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This time I am not in Bremen but in Seefeld near the North Sea. I was there for a weekend training in school management.


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The show starts with a live view at Gimp 2.5.0. Tobias Jakobs sent me a video about some new features and I add another one. This is alpha software, keep away if you are not helping with debugging. And never do “real work” with it.

Tobias Jakobs is well known in the German Gimp community for winning an image manipulation contest ahead of all the Photoshoppers.

Seefeld is in a nice area, as you can see from the aerial view. A lot of fresh air and the sea near by. We had not enough time for long walks but I could grab the shot above. You’ll see how I made that out of a pretty boring original image The original shot with a bit of curves and the healing tool. You can download the original and the processed shot in their full size at 23hq.com.

You all know Joseph AKA bluemojo. He covers the Foreground Select Tool and shows all the details. He also has a link covering the SIOX algorithm behind it. For all concerned minds – he dug his three girls out before the tide came in. 😉

Contact me!

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Episode 013: A Triptych and a Challenge for You!

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Triptychs – and nearly one hour of them. In this episode I’ll show you how to combine three images to one good looking set and get some frames and borders around them. Again a layer mask is used to partially edit a picture with the curves tool.

tryptich-mtg.jpg

The idea to this show came from this thread at the Tips from the Top Floor forum.

More about triptychs can be found at the Wikipedia here and here. More triptychs can be found here at google.

And I have a challenge for you. Make a triptych and put it online at the photogroup “meetthegimp.org” at 23. (23 is a friendly danish image hoster. I am their customer since flickr.com decided to censor my access to images because I am living in Germany.) I’ll show all the images in show 16 – so you have time up to October 16 or so to upload your stuff. I have asked a potential sponsor 23 to donate a bit – so it is possible that I have something as a price for you. (No, it’s not a license for the full version of the Gimp….. 😉 )and they have given me some codes for getting a year of full service at 23. I’ll choose the winner (if there is a price…) by random – so equal chances for all.

The TOC

00:24 Welcome to triptychs
04:44 The source images
07:46 Resizing the images
09:25 Make the background
12:40 Placing the images on separate layers
16:36 Set the background colour
17:10 Frame each image using layers
20:45 Frame the triptych by stroking selection
24:50 Fine-tune the images
25:00 Use curves to get part of the image right
28:38 Use layer-mask to isolate other part of image
36:52 Add a caption using the text tool
40:00 Save the file
40:40 Resize for the web
41:05 Sharpen the individual images
43:00 Re-do the caption
44:16 Re-save as JPEG
44:53 23hq.com
46:15 – mtg-triptych tag
47:55 – Add image to Meet The Gimp group
51:42 The End
TOC made by paynekj

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The files from this episode.

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Episode 009: Saving a Chapel (…..from underexposure)

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Norman mailed me two images – this was the original shot made by his son.
chapel-before-500.jpg

… and he made this out of it.

chapel-after-500.jpg

Quite impressive. I redid his work in the video and added some extras for the sky. You’ll see an other way to rotate an image, two ways to blend different versions of an image with a layer mask and a bit more about curves. I got this as a result.

chapel-rolf-500.jpg

Edit: Look also at the next show. I made a big blunder in this one and had to fix it in the next.

I promised some links:

Tim Jedlika shares some of his webspace to host the picture files. His gallery can be found here.

The wine.

The files from this episode.

photocast_network_button_120.gif

The TOC

00:23 Welcome
00:33 The original image by Norman
01:33 EXIF information
04:39 Re-sizing (just for the show)
05:18 Rotating by measuring
08:00 Make a layer copy and use the curves tool
10:23 Another layer copy for the sky
10:50 Add a layer mask
11:16 Gradient tool
17:23 Overlay layer
18:27 Cropping to a fixed aspect ratio
20:30 Sharpening
21:50 Save the image as jpg
22:38 Re-size for web
24:52 Thank you and goodbye
25:59 I’m back!
26:39 Fixing the sea
31:52 Closing remarks
34:13 The End
TOC made by paynekj

Contact me!

You can leave your comments on this blog, write me a mail or go to the Tips from the Top Floor Forum.

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

Episode 007: The Curves tool

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In todays show I cover the curves tool. With curves you can change the brightness and contrast of an image in a lot of ways. Either fine tune the shadows, midtones and highlights or do something very strange as in this picture.

Curves applied

This picture was made by Andra Sommer-Steinort for a workshop we both attend at the moment.

Meet the GIMP! is now listed in iTunes and Podcast Alley. If you like the show please let the people there know. 😉

The TOC

00:25 Site statistics
02:10 Curves tool
03:29 – separate colour curves
04:30 – sampling the image
04:55 – translation function curve
07:20 – linear vs. logarithmic mode
08:24 – curve type
08:59 – save/open curve
09:35 – using the tool – S curve
10:45 – loosing information
12:46 The End

TOC made by paynekj

You can leave your comments on this blog, write me a mail or go to the Tips from the Top Floor Forum.


Creative Commons License

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