Monday, June 29, 2015

AdDuplex Windows Phone Device Statistics Report – June, 2015

The countries we look at in details this time are: US, Brazil, France, Italy, Germany, Poland and India.

We also take a new look at the devices in use and break them down by the size of the screen.

In our reports we try to present you with pure facts, mostly, but if you are looking for deeper analysis check one of these articles:

Friday, June 26, 2015

Who won a trip to GDC Europe and gamescom?

5 months ago we’ve launched interstitial ads and we wanted to reward our early adopters. Therefore we’ve announced a contest to win all expenses paid trip to the largest game industry event in Europe – GDC Europe and gamescom. So every Windows Phone developer who added AdDuplex interstitial ads to their apps and games before the 15th of June had a chance to get this fantastic prize.

Now the random generator has selected one lucky winner! We congratulate the creators of Real Speed Car: Need for Asphalt Racing and especially Konrad Karolczyk, who is going to GDC Europe and gamescom events on August 3-6 in Cologne, Germany!

Thank you all for using AdDuplex!

BTW, if you want to meet AdDuplex at this year’s GDC Europe or gamescom to talk about app growth or just say hi, then drop us an email at

Monday, June 22, 2015

Introducing bidding sub-system

Woman hand showing an euro coinAdDuplex is all about helping indie developers promote their great apps and games for free. In order to be able to do that we are using part of that exchange inventory for paid campaigns and support the free service this way. This means that paid campaigns was always more of a support function of the main service and we tried to provide it in a minimum viable way that is of value to advertisers, but doesn’t distract us from the main focus – the cross promotion network.

Having said that, over the years we’ve introduced additional features (various targeting options) and statistics provided to advertisers. But the core principal was stuck in 2011 – campaigns were sold in preset fixed price packages. This meant that advertisers willing to spend more and get a bigger chunk of the traffic in popular demographics weren’t able to do so, and advertisers with focus on less lucrative areas were essentially overpaying for space that not many other advertisers wanted.

So the time has come to change that…

Tuesday, June 16, 2015

Creating an image ad that meets the file size requirements

As a developer you may not have spent a lot of time thinking about the size (not the dimensions) of the images you use in your app. However, when it comes to sending images over a network the number of bytes that are transmitted affects the time it takes to transfer the data that makes up the image and the cost of sending that data over a network. For this reason we limit the size of images that can be used for ads. For banner ads the limit is 25KB and for interstitial ads the limit is 256KB.
partial screenshot of ad configuration screen that shows the file size limit

We get a number of questions about how to create images within these limits so I’m going to show you how. I’ll provided an example of creating a banner ad that fits within the size limit but the same principles apply to interstitial ads too.

Why is this an issue?
In an image that 768 pixels wide and 128 pixels tall that’s 98,304 pixels in total. If using a bitmap format, such as PNG, that requires a separate byte for the Red, Green and Blue value of each pixel we need 294,912 bytes. When including the additional required information and file headers we can end up with an image over 300KB in size. (It'd be even more if we needed to store alpha values too but fortunately image ads don't need any transparency.)

To prove this point, here’s an image where every pixel is a different color. (If interested, it was created with this code.) The size of this PNG image is 302KB.
PNG image where every pixel has a different RGB value

Different image formats store the image information differently and can result in different file sizes. Here’s the same image saved as a JPEG.
JPEG image where every pixel has a different RGB value

This image is just 30.9KB (almost a tenth of the size). There is more that can be done to affect the size of an image though and that’s what I’ll demonstrate now.

Here’s a banner ad, for a fictitious game, that we’ll use for the demonstration.
Monkey in tree with app title text "Monkey puzzle"

As it stands the image is 231KB and so much larger than we can use.

Before we consider changing the format let’s look at what can be done to decrease the size of the PNG.
I’m going to do this with the excellent free tool Paint.NET. If you’re not familiar with this application it is free image and photo editing software for PCs that run Windows. You can download it from
When we save a PNG file from Paint.NET there are some options available.
Paint.NET PNG save dialog with "Auto-detect" level selected for Bit depth
Here you can see the default settings that were used to create the original image above.
The fact that this dialog shows a preview of the image and the size of the file that will be produced is very useful.
As we change the Bit Depth you’ll notice the file size changes.
Paint.NET PNG save dialog with "32bit" level selected for Bit depth
Dropping to 32 bits increases the file's size to 257.3KB.

Paint.NET PNG save dialog with "24bit" level selected for Bit depth
At a bit depth of 24 we see the file size of 231 KB and so can infer that this is the automatic value that was selected.

Paint.NET PNG save dialog with "8bit" level selected for Bit depth
At 8 bit we see the file size drop to 54.6KB but this is at the cost of image quality. You’ll notice that the blurred leaves around the text aren’t as smooth.

Paint.NET PNG save dialog with "8bit" level selected for Bit depth plus dithering and transparency set to zero
If we then take the settings to their absolute lowest and set the dithering and transparency threshold all the way down to zero the size of the file only gets down to 41.2KB and what were intended to be blurred leaves in the background no longer look like the original due to the inability to have the number of different colors in the file to create this effect.

As we can’t create a version of the desired image as a PNG that fits within the imposed size limit we need to consider other options.

Only JPEG and PNG files are supported for ads so that limit makes our decision of what other format to use easy for us.
If we weren't limited in this way the selection of a format only becomes slightly more complicated. As a very simple way of determining which to use, PNGs are better for line based drawings and JPEGs are better when using photos or gradients. As you might expect a question on the differences between image formats has been asked on StackOverflow and there’s a very good summary of the differences in one of the answers.
As a JPEG of the highest quality, the file size is 90.1KB
Paint.NET JPEG save dialog with 100% quality level selected

Paint.NET provides a single setting when saving a JPEG file but it’s a very powerful setting. By adjusting the quality of the image that is output we can create a file that is usable within the imposed restriction.
In this case we need to lower the quality to just 74% to get what we need.
Paint.NET JPEG save dialog with 74% quality level selected
This image also preserves adequately smooth blurring of the leaf background which was the effect I was trying to achieve.

Paint.NET isn't the only option for controlling the size of saved images. Gimp is another free to that also allows control over the output file. In fact it provides even more options than Paint.NET to control the output. The difference between the two applications is that Paint.NET shows the preview in the same window as the setting, while GIMP updates the image in the original window.
GIMP JPEG export dialog

Whichever program you use to create your banner and interstitial images there are two final tips I’d like to share.
  1. Make the image size as small as possible without impacting quality. This will allow the image/ad to load faster and therefore be potentially seen by more people.
  2. Test your image on an actual device to make sure it still looks as good on a small screen as it does on the monitor you upload it on.

I hope this helps you when preparing the images you use for your ads but if you still have any questions please get in touch via

Wednesday, June 10, 2015

Ads in Mobile Apps and Games 101. Free eBook.

797x435Everybody knows what a mobile ad is and how does it look like. But for an indie app and game developer that might be not enough while choosing the right monetization method or trying to reach the hearts of their potential users’. Therefore, recently we published a book "Ads in Mobile Apps and Games 101" based on experience we’ve gained working with those thousands of mobile apps and games.

In this book you'll find the main terms used in mobile advertising industry, get to know how to set goals and measure the effectiveness of your ad campaigns. And we’ll try to answer the question why you should definitely consider advertising as a monetization model for your mobile apps and games.

You will find a free PDF version here.

Monday, June 8, 2015

Developer Economics Survey. 2015 Developer Skills Census


Our friends from VisionMobile are running a Developers Economic survey that you should definitely submit.

We’ve used some data from their earlier surveys quite a few times and we find it really interesting and useful. It helps you get a better view of developer ecosystem as it’s the largest, most global app developer research & engagement program out there.

This survey will be closed on 11th of June so we encourage you to submit right now and be sure not to miss the deadline.

As always, key findings from this research will be available as a free research report by the end of July. Moreover respondents to the survey can also claim cool prizes like Lumia 930 or an Oculus Rift DK2!

Wednesday, May 27, 2015

AdDuplex Windows Phone Device Statistics Report for May, 2015

This month see the trends for the last few months continuing to play out. The Lumia 520 continues to remain the post popular device but it still losing market share while the 630 and 535 are gaining.

We see a surprising increase in the number of devices already running Windows 10.

Plus we look at Mexico, UK, Finland, Spain, Russia, India and Australia.