Episode 164: High Pass Sharpening

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Sharpening is a part of nearly every image processing. Selective sharpening allows to sharpen the important structures without to “enhance” the noise in the image. Already in Episode 6 I have shown a way to do this. And here is another way, High Pass Sharpening. It is often used in Photoshop tutorials and has no standard entry in the GIMP menus.

One step involves blurring – and this leads to a lot of different possibilities to change the effect. I explore asymmetric sharpening by blurring only into one direction.

Of course there are plugins available at the GIMP plugin registry.

A description of several sharpening methods is in our Wiki, I’ll add the high pass method today.

I got the recipe for this from a (very good) German book by Jürgen Wolf.

The TOC

01:48 Good German book: Jürgen Wolf, GIMP 2.6
02:00 GIMP 2.8 release late in 2011!
02:20 Preparing the image
02:40 Rotate
03:30 Crop
04:10 Contrast, black point and white point adjustment with the curves tool
05:30 The recipe for Highpass Sharpening
05:40 Duplicate the layer twice
05:50 Invert the colours
06:00 Set layer mode to Grain Merge
06:10 Blurring
07:00 Merge the top layer down and set the layer mode to Overlay
07:50 Adjusting the effect with the opacity of the sharpening layer
08:00 Sharpening in only one direction
09:50 What is Grain Merge doing?
11:00 How does this work?
14:50 Scripts at the http://registry.gimp.org

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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.

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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 112: Two Candles

112
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It’s just a bit after Midnight here in Germany – and so at least for nearly half the world still Friday, July 24th. And that is the second birthday of Meet the GIMP.

I cover two questions for this is the first HD show – and it took ages to render. I will have to adjust my workflow. 😉 I start with a problem of Ivo, the producer of Autozine – an online car magazine made with GIMP. He wants to change reality a bit and move letters around in an image.His images are in the companion file.

Then I tackle selective sharpening again after I got a question about how to further control the sharpened area. In episode 6 I constrained the sharpening to the edges in the image – here I reduce it to parts of the image.

In case that you wonder why there is no sharpening while I paint the antenna – have a look at the “eyes” in the layers dialog box….. 😉

This post will be updated tomorrow – then there will be also a mobile version and the companion file. Good night!

Mobile version of the vido is in the making is ready – I hope it will play everywhere.

There are comments about problems with iTunes and this episode. Is there anybody who can play this in iTunes?

The Mobile Version is a quick and dirty build with Handbrake. Does it play? Where? Where not? And why is it so large? 😉 Update: newer version in a bit larger and different encoding. Please check!

Episode 095: Shrinking! (1)

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95

Again I steal an idea from the forum. It’s making fake tilt shift images. They look like images of model railway landscapes but are made from reality. Have a look at the forum for links to images by Bert and others.

I do half of the work in this podcast – planning the image and give the real world a plastic look. Next week I’ll add the focus blur that is so typical for macro shots.

But at the start I show that I have learned something from Philippe: Look carefully at an original. The image on the right is a H0 scale model in the sand on the Weser beach – real plastic.

The companion file contains the original shots – the xcf will follow next week.

The TOC

00:30 Fake tilt shift images
01:50 Analyzing a macro shot of a toy
05:30 The real image
06:30 What shall be in the focus?
13:00 Rotate before crop and resize
16:00 Inside out crop
17:30 Scaling down
18:00 Analyze the plastic look
19:30 Selective sharpening
24:30 Unsharp mask for getting the plastic look
28:50 Specular highlights

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Episode 006: Selective sharpening

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Every digital image needs sharpening. But sharpening increases the noise in the image. In this episode I show a way to sharpen only the areas that need to be sharpened – the edges between different colours or levels of brightness. All the other parts of the image are left alone and so the noise stays down.

Sharpening should always be the very last thing you do with your image.

Picture for episode 006

Chris Marquard explained sharpening in Photoshop Corner No. 4 in his Tips from the Top Floor podcast.

I got the described method from the Gimp tutorial page.

Wikipedia describes the underlying process in this article about the unsharp mask. The links at the bottom of the page are very informative.

Meet the GIMP! is now listed in iTunes and Podcast Alley. If you like the show please let the people there know. 😉
You can leave your comments on this blog, write me a or go to the Tips from the Top Floor Forum.

The TOC

00:22 Welcome
01:00 The original image
01:25 Why we want to selectively sharpen
02:38 Copy the layer and add a layer mask
04:00 Edge-Detect on the layer mask
06:40 Blur the layer mask
07:12 Increase contrast using curves
08:34 Sharpen the image
10:25 Fine tuning
14:35 How sharpening works
15:49 tips from the top floor
18:26 The End
TOC made by paynekj


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