Sunday, 31 July 2011

Full Circle Podcast Episode 22 Mad Max Meets Ben Hur

Full Circle Podcast Episode 22 Mad Max Meets Ben HurFull Circle Podcast Episode 22, Mad Max Meets Ben Hur is available now from the Full circle Site.

In this episode, all things Chrome.
Full Circle Podcast is also a proud member of the Tech Podcasts Network.

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Additional audio by Victoria Pritchard

Show Notes

01:42 | WELCOME and INTRO

06:58 | REVIEW: Full Circle Magazine Issue #50
  • Dave: Ed's game review of Trine, p.37
  • Ed: Ronnie's KDE 4.6 article, p.20 and Robin's Gnome Shell vs Unity, p.24
  • Robin: Daniel Holbach's continuing series on Ubuntu development, p.17
012:33 | NEWS

36:51 | OPINION: All things Chrome: Ed's Samsung Chrome notebook. ChromeOS marches on, but for how long?

58:04 | Send us feedback: since Victoria continues to ask so nicely


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Runtime: 101 mins 33 seconds

Tuesday, 26 July 2011

Digital Watermarks: Part Two Heart of Darkness

In Digital Watermarks Part One, we looked at the need for digital watermarks and the simple steps to impose a visible watermark onto a digital image. As we found last time, a visible watermark placed in the center of the image is really difficult to erase and will remain even if someone crops the image, but it spoils a good composition. Time to go invisible.

A true digital watermark is a digital signature, a pattern of bits impressed into an image file that can be read by a viewing utility. A person viewing the file normally won’t see the it, but the hidden watermark stays intact even if the file is cut, cropped or otherwise manipulated. This is a very secure and unobtrusive method of watermarking an image…

With the right algorithms and tools you can embed an entire library of information inside a high resolution photo and not alter the visible image. At the high-end, digital watermarking involves cryptography and complex algorithms that are way above my pay grade.

The trouble with this method is the variety of image processing which can unintentionally or intentionally attack a watermarked document and render the watermark undetectable. High quality images are often converted to JPEG format to reduce their size, by which the data compression can destroy the watermark. Horizontal or vertical flipping, rotation and cropping can also render an invisible watermark undetectable.

However, if you feel the need to add a simple, hidden watermark to your images using the GIMP, Gnu Image Manipulation Program, let’s give it a go. There are various techniques documented on the Web, none of them foolproof; this one mostly works but not in all cases.
We’re going to create a watermarked copy of an image and use the original as the key to reveal the hidden mark. I’ll assume some basic familiarity with the GIMP and that you read Part One.
  • Open the GIMP with a new transparent image. Create a text layer for your copyright assertion using a clean, legible font. Text layers have peculiar properties, so Merge Down the text layer onto the transparent background.Next, convert your image to a pattern.  Go to Select Menu, All (or use the shortcut Ctrl – A) and copy to clipboard.
  • Using Windows, Dockable Dialogs, Patterns, open the Pattern palette. This is pre-populated with the sample patterns that come with the GIMP.
  • Click the Auto button and GIMP will automatically pickup the selection as a pattern for immediate use. The first pattern in the grid will be the selection you’ll use as the watermark. As it has a transparent background you’ll probably see a blank white square, make sure it has the heavy black border indicating it’s active and it says ‘Clipboard ( 512 x 492)’ where the numbers are the dimensions of your watermark selection.
  • Open the image you want to watermark and create a duplicate of it, Go to Image, Duplicate (or press Ctrl – D. Save it under a new name – don’t mess up your original image, you need it for use as the key!
  • Create a new layer, make sure it’s highlighted as active.
  • Go to the Pattern palette and perform a click-and-drag on your watermark pattern, dragging it over the image to be marked. The Pattern function should automatically tile this across the whole image.
The next step is more experimental.
  • Reduce the opacity of the pattern layer so that it is no longer visible but but DON’T set it to zero. 
  • Zoom in play with the opacity settings, keep it as high as you can without the pattern becoming visible with your Mark I human eyeball. Between 2 and 10 is good. 4.0 worked on my Sedona landscape.
  • Save this version as the one you’ll post to the public. This should work for .png and .jpeg files (but only if you keep the compression to a minimum).
The Case for the Prosecution
The day comes when some despicable cad rips one of your images and you need the evidence to go before the Bench.
  • In the GIMP, paste your original and the swiped, watermarked copy as separate layers into one image file.
  • This is what they call on the TV makeover shows ‘the reveal.’ In the Layers palette, highlight the upper layer as shown in the attached and set its Blend Mode to Grain Extract.
What this does is subtract all the common elements in both images, leaving only the differences visible; in this case your copyright assertion!

Drum roll, please, I thank you!

A few things to note:
  • You may find that Blend Mode, Divide also reveals the watermark, depending on the image.
  • Saving your images as .jpegs with high compression will introduce what are called compression artifacts; the data lost in the process can be enough to destroy your hidden watermark. The enterprising thief will often convert images between formats and scale to low resolutions, destroying the watermark in the process.
  • You can try different fonts, font sizes and colors in your patterns which may work better or worse with the different images you are marking. Go for contrasting watermarks against the dominant shades in your images, light-to-dark, dark-to-light. 

Wednesday, 20 July 2011

Return to Blogger Recent Posts

At the beginning of the month, eagle-eyed readers of my Blogger site will have noticed up to three "Recent Posts" widgets on trial in my layout. This is purely down to the fact that all of the Recent Posts, Recent Posts Advanced widget and another custom feed method all broke down in the updated version of the Blogspot platform and nobody seems interested in fixing them!

Yes, each would appear to work at first, but then blank out and no amount of refreshing would bring back my beloved content. So I tried some other methods of achieving what should be straightforward on Blogger...

One is to create a simple feed for recent posts; from the Blogger Dashboard, Add a Page Element, add a Feed (click “add to blog” under the page element Feed), configure the feed by adding the blog feed URL in the box:

Click Continue, change the title, save it, done! You can also choose to show the item dates and author.

My second was a find of some Javascript code which allows for the current title, thumbnail and snippet format.

In Dashboard > Design > Page Element > Add a Gadget > HTML/JavaScript, pasting the code (bottom), then replacing the URL with your blog URL (
The optional settings include changing the number of posts from the default of 8 recent posts and changing the default height of the gadget on the page (thereby removing the scrollbar), by altering line #4 in the code:

    {“URL”:””},”height”:”500“,”count”: 8 }

I found emptying the value for height worked and 6 recent posts gives me a decent list length.

The third time I built the castle in the swamp and this time the castle stayed up! RC

Recent Posts Gadget code courtesy of  projectdigitaltomato:

No snippet

Use this code if you don’t want post snippets to show. Only thumbnails and titles will show.

Thursday, 14 July 2011

Review: Samsung Galaxy Tab 7-inch

I got my paws briefly on a Galaxy Tab 7-inch recently. It belongs to a friend in the construction industry (Alan, not to be confused with Allan) who initially raved over it and in two weeks began fault-finding. This is one of the tablet devices released in response to Apple's iPad. It was a fine alternative to the iPad-I in terms of it's market pitch, but since the iPad-II came out, it looks like an expensive me-too with a smaller screen. The question is, has Samsung compromised too far in the attempt to be distinctive...?

Tuesday, 12 July 2011

How-to: Digital Watermarks Part One Darkness Visible

You know watermarks; they are the authentication marks that appear on bank notes, branded stationary, company documents and education certificates. Those are the visible watermarks we see everyday. Hold up a bank-note to the light and there it is, molded and imprinted into the paper.

You will also see watermarks on reproductions of photographs and other artworks, a visible assertion of copyright, usually the copyright-holder’s name and logo. This adds a third utility to the watermark: a sign of authenticity to combat fraudulent use and unauthorized copying, an assertion of rights by the rights-holder and a permanent branding or advertising…

Digital watermarking is the extension of this utility into the digital world. It is easy to reproduce and distribute identical copies of digital information, be it images, text or audio. There is no shortage of data bits, as the entertainment industry has discovered – or anyone who shares images from their digital camera. You might think fraudulent use of digital photos is somebody else’s problem. Leaving aside the large travel companies I’ve worked for, which have large and expensive image libraries, I know several freelance photographers for whom it’s a real concern. Put an image gallery up on the web and it will likely be indexed by the search engines, where less than scrupulous people can find it and ‘rip’ it for free, passing it off as their own and maybe making money off your work.

The answer is to watermark your digital images. There are two ways to do this; visible and invisible. We’ll look at invisible watermarking in part two.

For all digital photos, you can put an invisible copyright in the Exif/IPTC fields of the image file. Most digital cameras can be set up to insert a copyright statement automatically. The trouble is there are lots of free image-editing utilities you can use to take it out in one click.

Visible watermarks work well enough as they are permanently ‘in your face.’ A watermark placed in the center of the image will remain even if someone crops the photo and it’s really difficult to erase, but a watermark bang in the middle makes it hard to enjoy looking at the photo. You could try placing the watermark around the edges, but this is easily defeated by cropping the photo. The size and placement of watermarks is the compromise you have to make using your own judgment. To paraphrase a marketing quote, “the size of the logo should be proportional to your ego and the picture’s value; and inversely proportional to the quality and interest of the picture.”

Onto a practical example using the image editing application The GIMP, the GNU Image Manipulation Program. I’m no artist and there’s usually a dozen ways to get the same result in the GIMP; these are mine.
  • Open your photographic masterpiece and immediately Save As… or Save A Copy so you don’t mess up the original and can keep additional layers. You will need the Layers palette so press ctrl – ‘l’ to open it if it is not already visible.
  • Create a text layer for your copyright assertion using a clean, legible font in a contrasting color appropriate to the portion of the image over which it’s placed.
  • Watermarks are typically colored along the grayscale between black and white. Any other text color will require you to use the Value mode in your Layers dialog.
  • Choose your text foreground color first, then select the Text Tool icon, it’s the full black ‘A’ in the Toolbox. Alternatively press the ‘t’ key.
  • Type your text.
  • You can use the Character Map application to find and include the Copyright mark ©.
  • Size and position it within your image.
    ( I’ll also select Image, Image to Layer Size to make the text layer the same dimensions as my photo for later on)
  • If you want to make your watermark more robust, you could use Layer, Transform, Arbitrary Rotation, Angle -45, to place your watermark diagonally, which defeats removal by edge-cropping.
    (If you then decide to edit the copyright text it reverts to plain horizontal positioning, however)
Plain text is overly intrusive and doesn’t look like a watermark, so select your text layer…
  • You could just change the opacity of the text to a semi-transparent state, changing it down to between 10% and 30%, which is visible but not intrusive, or…
  • Change the layer mode to Overlay which achieves a similar result in one click.
This is still quite intrusive. What we want is something more subtle. Let’s try this:
  • In the text layer, select the text; Select, By color
  • Delete the text to leave the text outline as a selection. Now to try some filters…
  • Filters, Map, Bump Map. The previews doesn’t show much, but hit OK and what you get is a subtle text outline of your copyright statement floated over your image.
  • We can make something a little stronger than this. Undo the Bump Map filter, we’ll go again.
  • Add a new layer below your text layer, filled with 50% gray (127,127,127) and then Layers, Merge Down your text layer.
  • Select the text; Select, By Color. Now you have the selection, you can delete the text to leave its outline.
  • Apply Filter, Decor, Bevel to the selection
  • Now select the gray background and delete it. This gives you a beveled watermark. You could achieve something similar with the Emboss filter.
When you’re happy with your watermarked version, go to the File menu and choose Save As. If you  save the image as a .peg or .png file for use on the web, the GIMP throws a dialog telling you those formats can’t handle layers and you need to flatten the layers. This isn’t your master copy, so that’s okay… right?

This is fine for small galleries of images. You can always paste your finished copyright layer into each image in the set. For larger numbers of images, where you probably need to resize them en route, a scripted solution or automated tool such as ImageMagick is probably the way to go. RC

Sunday, 10 July 2011

Full Circle Side-Pod Episode Nine: A Mish-mash of Technologies

Full Circle Side-Pod Episode Nine: A Mish-mash of Technologies is available from the main site.

In this episode, Social innovation, open data and FOSSbox.

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MP3 18.6Mb

Full Circle Podcast is also a proud member of the Tech Podcasts Network.

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* Robin Catling (blog at, twitter @robincatling)

* Les Pounder (blog at twitter @lespounder)
Additional audio by Victoria Pritchard

Show Notes

00:59 | WELCOME and INTRO

01:55 | Feedback on the OpenTech Conference 2011, Saturday 21st May 2011.
OpenTech 2011 is an informal, low cost, one-day conference on slightly different approaches to technology, transport and democracy. Talks by people who work on things that matter, guarantees a day of thoughtful talks leading to conversations with friends.

08:09 | Interview: Glen Mehne of Social Innovation Camp:
Social Innovation Camp brings together ideas, people and digital tools to build web-based solutions to social problems – all in just 48 hours

17:44 | Interview: Paula Graham of Fossbox
Fossbox is a non-profit organisation supporting digital inclusion and helping other non-profits move towards lower-cost ICT systems with more flexibility and lower environmental impact.

30:51 | Interview: Lucy Chambers of the Open Knowledge Foundation
Founded in 2004, we’re a not-for-profit organization promoting open knowledge: any kind of data and content – sonnets to statistics, genes to geodata – that can be freely used, reused, and redistributed. We promote open knowledge because of its potential to deliver far-reaching societal benefits.

48:13 | FEEDBACK: How to get in touch with us

48:54 | NEWS: Competition for Ubuntu and Unity according to Distrowatch

56:17 | WRAP and OUTRO
 Please note: this podcast is provided with absolutely no warranty whatsoever; neither the producers nor Full Circle Magazine accept any responsibility or liability for content or interaction which readers and listeners may enter into using external links gleaned from this forum or podcast series.

Creative Commons Music Tracks
* Opening: ‘Knights of the darkness’ by Zero Project
* Main theme: ‘CCMixter’ by Code
* Incidental: ‘Funkorama‘ by Kevin MacLeod
* Incidental: ‘Techno-dog’ by Unknown, original recording royalty free under Creative Commons v2
* Opening dramatic dialog by Dave Wilkins and Robin Catling, from 2001: A Space Odyssey

Friday, 8 July 2011

Advertising on

Confusion persists over what you can and can't do on, that's the free service for Wordpress blogs hosted by the Wordpress folks themselves out of the goodness of their hearts. They run the advertising, they get the revenue. It should all be very straightforward but the rules don't seem to be encapsulated neatly in one place where we can all see them.

Run your Wordpress (.org) blog on a self-hosted domain and you can do anything you like. You're the one responsible for maintaining it on whatever server you've paid for, knock yourself out. The .com blogs are a different matter... runs ads on our blogs and has done since 2006. User-generated advertising is not allowed on free hosted blogs. The only exceptions are for high traffic blogs that qualify for and are accepted into the Ad Control program, and very high traffic blogs that qualify and are accepted into the paid VIP hosting program. More information can be found at

Which blogs are allowed to use AdSense and Skimlinks?
Those would be the blogs with high traffic of 25,000 or more page views a month. VIP blogs like CNN and the NFL, paying $2,500 a month, can run their own ads.

If you do get over the magic 25,000 mark, you can qualify for ads at a 50/50 split with Wordpress, but the amount varies with the click-thru rate. Don't give up your day job.

Other conditions for using AdSense and Skimlinks
There are further conditions for use of AdSense and Skimlinks, which are allowed only for blogs with real content, not skimming, hyping or solely for advertising product and definitely not spamming. The Terms of Service on Advertising is the usual 'EULA minefield' and Wordpress gets to decide what's appropriate not you. 

To get AdSense and Skimlinks for your blog
You fill in a form on the Terms of Service on Advertising page to apply. will review your blog and approve or deny you. You also have to sign up for AdSense and Skimlinks accounts. You have to get approved for the latter as well, but both should be free.

After you get approved, Ad Control appears under your Settings menu when you log into, where your account ID's are entered.

'Driving Traffic'
In summary, free blogs hosted by cannot be used to drive traffic to third-party sites by means of advertising and/or affiliate programs. E-commerce transactions via shopping carts and the like cannot be conducted on blogs. No retailing or reselling the work created or services provided by anyone other than yourself is allowed.

Affiliate marketing blogs
The only exceptions with regard to affiliate links are summarized by Wordpress:
"Affiliate marketing blogs: Blogs with the primary purpose of driving traffic to affiliate programs and get-rich-quick schemes (“Make six figures from home!!”, “20 easy steps to top profits!!”, etc). This includes multi-level marketing (MLM) blogs and pyramid schemes. To be clear, people writing their own original book, movie or game reviews and linking them to Amazon, or people linking to their own products on Etsy do NOT fall into this category (" 

You can link to reviews in your actual post; book reviews, gear reviews and the like, but nothing is allowed in the sidebar section. 

One response from Wordpress support reads:
"If you write reviews for product on, it's ok to use their image and add an affiliate link.Other forms of advertising (including sidebar widget with Amazon affiliate links) at is not allowed.
For full details, please see: and If you require advertising, you might be interested in a self-hosted ( installation. There are no restrictions on advertising if you setup a self-hosted blog instead of a blog, but there are some added responsibilities. Please see this link to learn about the differences:

If you require an ecommerce site, advertising and/or affiliate links on your blog, you can hire a web host and get a free software install from The information at outlines the differences between free hosted blogs and software installs for self hosting.  

Also note that those readers using Firefox browsers with AdBlock Plus (42.8% of those surfing the internet) will not see the ads on your blog at all! RC

Wednesday, 6 July 2011

Bad Cat Humour

Humour. Remember that?

Yes, it's desperately close to the LOL Cats of 'I can has cheezeburger,' but I was given a copy of the 2011 Bad Cat Calendar from Workman Publishing and I happen to like July 23rd's cat.
"Normal service will be resumed just as soon as we've worked out what's normal anyway."