AI, the new secret weapon in the cloud photo-storage war.

Gigaom posted an article on “The Dropbox computer vision acquisition that slipped under the radar“. But I think it the article should have been called:

AI, the new secret weapon in the cloud photo-storage war.

Okay, this title is probably a hyperbole. But all the big internet companies offer a way to store and share your photos online. And to make their offer more compelling Yahoo, Google, and Dropbox all recently bought computer vision start-ups that will provide image recognition for their user’s uploaded photos. While Yahoo bought LookFlow, Google bought DNNresearch.

Microsoft is researching on image recognition for a long time and I am sure they will soon integrate some of their algorithms into their cloud products. And Facebook just founded an internal AI group.

And to get a look into the future without having to upload all your photographs to the internet, try the iOS app Impala. The app will analyse and categorise all your photographs on your device. It was created by EUVision technologies, a spin off of the University of Amsterdam commercializing their research efforts. 

After the negative conclusion from my last post about the closure of Everpix these are positive news for the machine learning market.

The end of Everpix, a sad week for photographers and machine learning researchers.

This week the photo storage service Everpix announced, that they will close down. They did not have enough paying costumers and could not find new investors.

That is sad. Not only because it was the world’s best photo startup according to the Verge, but also because it was the only company besides Google that used new machine learning techniques to help people manage their photo mess.

everpix home screen

Everpix home screen

Their closure can be seen as an indicator that end users and investors are not ready yet to spend additional money on machine learning algorithms.

Flashback mail

Flashback mail

Having read some articles and the associated comments[1, 2], it is clear to me that not their use of sophisticated machine learning algorithms but the daily ‘flashback’ email with pictures taken on the same day in previous years was the more popular feature. In fact, I did not even see one single comment about the algorithms that analysed the pictures.

But maybe their algorithms were just not good enough.

Unfortunately I could not try out their algorithms myself. My pictures just finished processing a few days before they announced to close down. But I found a comment of one of the founders on Hacker News, saying that they used a deep convolutional neural network with 3 layers for the semantic image analysis. This is the same technology Google now uses for their photo search.

But they were unhappy with the results of the algorithm so in January this year they changed their approach as their CTO, Kevin Quennesson, explains in ‘To Reclaim Your Photos, Kill the Algorithm’.  He writes: “If a user is a food enthusiast and takes a lot of food close-ups, are we going to tell him that this photo is not the photo of a dish because an algorithm only learned to model some other kind of dishes?” They found that the algorithm’s errors were not comprehensible for the end user.

So they planned to change their system. As I understand it, their old system learned and used concepts independent of the single user. But the new system also uses pictures of the same user to infer the content of a new picture. He calls this “feature based image backlinks”.

Explanation Feature-based Image Backlinks

The graph shows how a picture of a dish can be correctly identified because the content can be inferred by similar pictures of the user that the system identified correctly before. – from Quennesson’s blog post

Regardless of the success of Everpix, I think using the context of an image more is a helpful and necessary approach to build systems, that will reliably predict the content of an image in the future.

In any case I wish we would hear more about the underlying algorithms, what they tried, what worked and what not.

How to archive my tweets?


So, it looks like IFTTT deleted my recipe, to avoid drawing Twitters wrath on themselves. I will mail the customer support and ask, what happened…

[Original article]

tldr: IFTTT recipe: Archive my tweets to dropbox!

Even though I am a happy Twitter user, it makes me feel very uncomfortable that I cannot easily access all my old tweets. For that reason I used IFTTT and Dropbox for the last several months to archive all the new tweets, so that I have access to those at least. But after Twitter forbid IFTTT to directly access the tweets, this solution was no longer working. But as clever users found out, Twitter is still providing a RSS feed containing all publicly sent tweets  for each user.

As a result it was very easy to get the whole pipe line working again. If you want to try it youself just use my public IFTTT recipe: Archive my tweets to dropbox! You only have to replace my Twitter handle with yours…

Btw: Please share if you have other useful recipes!

International Computer Vision Summer School (ICVSS) 2012, a review

This blog post is intended to be informative for students who plan to attend ICVSS for the first time and to give feedback to the organizers, because I had not time to fill out my feedback-form back there ;)

It is based on my experiences of participating in this years ICVSS 2012. In this post I will only talk about the organizational side. Of course the lectures are the most important part of the summer school, but it is easier to establish if the lectures are relevant to you than to find out if you would enjoy the summer school.

TLDR: I liked it very much. If you are a 2nd or 3rd year PhD student and have 1300€ to spend, definitely go!

What is ICVSS?

The International Computer Vision Summer School is a yearly one-week conference for students in the field of computer vision held in Sicily, Italy. In contrast to normal conferences it is less formal and the aim is to learn rather than to present. For that reason they invited renowned researchers and professors to talk about he “theoretical and practical aspects of real Computer Vision problems as well as examples of their successful commercialisation”.

The summer school’s program comprises of

  • lectures,
  • workshops (which are a like practical lectures),
  • poster presentations by the attendees,
  • a reading group,
  • a essay contest (Brady Price),
  • a written exam and
  • social events.

It is organized by the University of Catania, Sicily, Italy and the University of Cambridge, UK.

The Program

All five days followed roughly the same pattern. They started with breakfast at 8h followed by two lectures before lunch. After lunch there was one more lecture followed by a coffee break. The after-coffee-break program varied throughout the week:

  • The first two days students were presenting their posters,
  • on the third day there was a guided tour to ancient city of Ragusa Ibla,
  • on the fourth day the afternoon was filled with the Reading Group and
  • on the last day Friday, there was the examinations, the student presentations and an award ceremony.

Generally speaking everything was very well organized, even – if you allow me this cliché – from a German point of view. The issues I was told or experienced myself were mostly due to circumstances outside of the ICVSS staff’s influence like airlines or the hotel being sloppy.

In fact all lectures and events were starting so punctual that I had trouble being always punctual ;)

They also managed to give the summer school a nice pace. There was no downtime to get bored and you never had to stress to see or do the things you wanted.


My only issue with the program was that the lectures were too long. Some lasted 2h without break. They changed that halfway through the summer school and I hope that sticks for the next years. I would suggest cutting the all lectures into blocks of 50min followed by 10 min breaks.

Poster Sessions

In the poster sessions students could present their work to the other students to get feedback, which is always very valuable as the other participants are from a similar field with out being too familiar to you work to ask the right questions.

The was also a competition for best poster. The two winners received a money price (700€) and were asked to present their work in a short talk on Friday after the examinations. (Congratulations again to Christof Hoppe with Photogrammetric Camera Network Design for Micro Aerial Vehicles)

My only quarrels where that some people did not go to the second floor, because there were not enough signs. Furthermore the rooms were too crowded, especially in the corners where posters were hanging on each side, although there was unused room upstairs in the gallery.

Reading Group and Essay Contest

The aim of the reading group is to teach and practice the skill of reading research papers. To take part you have to prepare a homework “studying (not just reading) one or more topics provided by the school committee, and tracing the ideas as far back as you can.” This year the topic was image features and last year it was shapes. The groups and individuals with the best and most interesting submissions will be asked to present their work during the reading group at the summer school followed by a discussion. The group or the individual with the best presentation is awarded a money price of 1000$. If I remember correctly only 18 groups or individuals participated and you can listen and take part in the discussion even if you haven’t sent in homework. Never the less, I would urge you to hand in something as the organizer of the reading group, Stefano Soatto, give extensive feedback.

The essay contest (also called Brady Price) was about discussing the current and the future “real world” social impact of computer vision technology. There were two topics to choose from (Urban Landscapes and Computer Vision and Medicine) and the two winner were asked to read out their essay and received 600€ in price money.


The exam consisted of 37 multiple choice questions covering the lectures and workshops. You had to answer 17 correctly to pass the exam and receive a separate certificate. Only a few of the lecturers gave useful example questions after their lectures so we were not really sure what to expect. In the end the questions were quite fair and sensible. I would say, you can pass studying in your room at night if you paid attention in all the lectures.

Social Events

I actually attended my first beach party during the summer school. The other activities were also very enjoyable. Look forward to them.

Venue, Accommodation and Food.

When I told my friends about the summer school I found myself using the following phrase a lot:

It was the nicest prison I have ever stayed in.

Maybe I am just not used to resort vacation, but I think this description fits. The hotel is remote and you wont be able to leave the place and find anything in walking distance except for a small fishing village and a beach.

Nevertheless I liked the place, as it provides everything one needs. I even was able to buy some swimming pants and flip-flops I forgot back in Germany.

For each meal the hotel would provide a varied buffet and I can’t remember anyone complaining about the food. If you are vegetarian it is definitely doable without starving taste-buds.


The internet connection was bad! Very bad!! In theory there was WiFi in the lobby of the hotel, the lecture hall and in the foyer of the lecture hall, where the organizers have their temporary office. (Note: No WiFi in the rooms!)

But in practice the WiFi connections were so slow that sometimes not even emails would load and there was a connection timeout of like 5 mins after which one had to re-enter a personal code of nearly 20 characters, which made using the internet on the phone way more annoying than fun. As I wrote the resort is very remote, so it is probably cost prohibitive to get faster internet for the few internet addicts visiting once a year. Which is a pity as the organizers try to push the use of social media (facebook/twitter) during the conference, which is imho a fun idea. But my proposal would be to shut off the WiFi in the lecture hall. As a result, people are less tempted (and less frustrated) by the internet during the talks and there would be more bandwidth left for the people sitting in the foyer (doing important stuff ™)


If you coming from Europe this summer school will cost you roughly 1650€. (600€ for the school, 750€ for a single room and 300€ for the flight.  You can cut the costs to 1250€ by reserving a bed in a 4 person room (450€) and by booking your flight early with websites like  This is still quite expensive, but I was quite satisfied in the end. There were no hidden costs, they didn’t seem to throw out money for totally unnecessary things and they didn’t try to sell things, which I cannot stress enough.

More warning than recommendation is this résumé by Roman Shapovalov, who choose a hotel in the near village to stay for ICVSS 2010.


As the organizers told us in the opening presentation, the most important part of this conference are the people we meet. For some working on their own at their home universities this might be a first time to feel as part of a community. And the process of becoming a community is deliberately amplified by the choice of such a remote venue. For every meal and for every activity we stayed together, so you got to know the other people very fast.

Also most of the lecturers stay for more than a day, so this was a great chance to interact with them in a very relaxed environment. Some even brought their families, which shows how much they enjoy this summer school themselves.


I liked it a lot and I think I will go again. If not next year, in 2014, even though I will have to pay it from my student scholarship. I’ll be probably booking a bed in a four-person room, which makes it cheaper and more interactive.

My recommendation is to go as soon as you finished your literature review and have a some results to present. Make sure you have something to show and talk about. Than you can learn and profit from the connections you make and the tips you receive a long time.

There is also the CVML Summer Schools organized by INRIA, France, which ended this year just before ICVSS. If you have enough money then go to both, otherwise choose with regard to the speakers.


  • Prepare an elevator speech
  • Leave your notebook at home. Remember there is no internet and you are there to meet people. You can bring yours slides on a USB stick if you are planning on winning the competition.
  • Don’t go to bed too early, sleep after lunch. You don’t miss anything and it is too hot to do anything anyway.
  • Plan one or two days of extra stay in Sicily. It is easier to ignore the beach next to the hotel, when you know you have time afterwards to go to the beach – you pay for the return flight anyway! My recommendations would be Siracusa and Stromboli.
  • Don’t forget your swimming pants! You need them and they are expensive in the resort.

Further reading:

Did you attend ICVSS? What was your experience?
Thinking about going and having questions left?
Leave a comment!

[update] corrected breakfast time and modified intro

Book: Programming Computer Vision with Python

Book cover: Programming Computer Vision with Python

In case anyone missed it, you can download a very mature draft of “Programming Computer Vision with Python” at This book takes a fresh approach at introducing people to the computer vision field. It is aimed at beginners, who have some programming experience (not necessary Python) and basic understanding of linear algebra (matrices and vectors) and analysis.

The covered topics are (as taken from the TOC):

  • Basic Image Handling and Processing
  • Local Image Descriptors
  • Image to Image Mappings
  • Camera Models and Augmented Reality
  • Clustering Images
  • Searching Images
  • Classifying Image Content
  • Image Segmentation
  • OpenCV

What I like the most are the mini project like programming your own little augmented reality app or building a complete web app for content based image search. It is always great to have little working demos to show to your friends. I will definitely recommend it to anyone new and interested in the computer vision field.

The author, Jan Erik Solem, is Associate Professor at Lunds Universitet and co-founder of PolarRose, a facial recognition software company which was bought by Apple in September 2010.

You can buy the book from July on at or download, as said, the draft from the book’s website.

A list of lists of PhD resources

On your way to become a PhD, you not only have to learn how to do research, you also have to learn how to communicate your ideas comprehensible in text and speech, how to build the tools you need and how to survive in the microcosmos of supervisors, colleagues and under grad students of your research lab. But you are not the first to go through all this and people have written extensive advice for every problem you might encounter.  And as they are so popular right now, I present you here my: 

List of lists of PhD resources for computer scientists.

List of lists of lists

List of lists of lists!?

The most condensed summary I have found on the website of my work group IUPR. It is a good starter and gives one an overview of all the things one has to keep in mind and pay attention to.

From the most condensed to the most comprehensive. This collection links to nearly 100 articles on Ph.D. dissertation/research, presentations, writing,  reviewing/refereeing,  being a faculty member, job hunting, learning English and more. The list is overwhelming.

Links to documents on giving talks and writing papers and proposals.


If you did not actually study computer science (like me) or your courses mainly covered logic and reducing NP-complete problems, this site can probably help you a lot. Software carpentry is about learning the skills to write reliable software and using the existing tools efficiently. The website offers tutorials on basic programming, version control, testing, using the shell, relational databases,  matrix programming, program designing, spreadsheets, data management, and software life-cycles.

[UPDATE] How could I forget:

Like the well known Academia is “a collaboratively edited question and answer site for academics and those enrolled in higher education.” It is still in its beta phase, but growing everyday. I like the aspect, that it will be always more current and extensive than all the pages only maintained by individuals or single work groups. And if you can’t find the information you need, you can always ask for help.

So what do you think? Do you find these resources useful? Some of them are already quite old. Do you think they are obsolete? What are you tips? Which collections did I forget?

Collabgraph [Follow up]

Black Hole

When collabgraph divides by 0
from @nelas

I was stunned to see that more than 600 people had tried collabgraph in the past months. This is a huge number considering my expectations and its niche use case. So thank you for taking the time and leaving feedback!

Developing collabgraph and taking part in mendeley’s binary battle was a great experience. And without your support I wouldn’t have made it into the TOP10. I am especially grateful to all, who voted for me in the final vote!

And these black holes are created by papers with hundreds of authors, which is apparently quite common in the genome research society.

Use all the cores!

Use all the cores

Use all the cores with GPGPU and HPC

The last months I have been diving into GPGPU programming with (Py)CUDA. Everytime you are working with images you are faced with huge amounts of data, so more speed is always welcome. CUDA promises speedups up to 300x, but this comes with a price of having to implement more or less everything yourself on a low level. In times this can be very challenging, so to cheer me up in the hard times I made this picture based on a popular internet meme. I also think the GPGPU and HPC community is in need of some catchy visuals.  Read more about this and other memes at Know Your Memes, X all the Y.

Let me know, what you think and spread it!

Follow-up on Mendeley’s Binary Battle

Last week Mendeley announced the winners of their Binary Battle.  The first place goes to openSNP

With openSNP, you can share your personal genome from 23andMe or deCODEme to find the latest relevant research and let scientists discover new genetic associations. Werner Vogels, Amazon CTO and one of our star judges said this, “OpenSNP is cool. I have uploaded my genotype, and it is interesting to see it at work.”

Runner up is PaperCritic.

PaperCritic allows for post-publication peer review in an open environment. Rate papers, write critical reviews or read those from others.

The third place goes to rOpenSci,

which provides R-based tools to facilitate Open Science; including R packages for both Mendeley and PLoS.

I am more than content that my entry, Collabgraph, made it into the top 10. And I am thankful for everybody who voted for me the last month. Taking part in the Binary Battle was a valuable experience. Thank you again, Paddy, for hosting Collabgraph!


Vote for Collabgraph!

For the people who don’t follow me on Twitter:

Collabgraph made it into the Top10 of Mendeley’s Binary Battle!

I am really proud, especially considering the high quality of all the other contenders. But if you tried Collabgraph and found it useful or fun, I would be more than happy if you’d vote for me! The public votes and the decision of the (surprisingly high profile) judges will be aggregated to select the winner. The first price consists of 10.000$, 1,000 Amazon Web Services Credits and limitless fame! So please, if you liked it

Vote for Collabgraph!  :D