OCRFeeder 0.7.11 released

Here is 2013’s first version of OCRFeeder, version 0.7.11.

For this version, a number of bugs were fixed, especially some that were affecting saving and loading projects.
Some small improvements were also made such as being able to load multiple images at once and being able to choose the OCR engine from the command line interface version of OCRFeeder (using the -e option).

Now for the main feature, I developed something that had been requested by a good number of users: being able to easily choose the language for the OCR engine.
When I developed OCRFeeder, I wanted to make it easy for users to use system-wide OCR engines from the layout analysis that OCRFeeder performs but I also wanted it to remain powerful and that’s why the engines are configured in a general, abstract way, as if from the command line.
Some OCR engines support setting the language in order to get a better recognition and while, users could already set the language of an engine manually using the OCR editor dialog, they wanted to have a nice drop-down list with the languages instead.
This represented a real challenge: to keep the old and flexible configuration and, at the same time, offer a high-level way of choosing the language.

OCRFeeder's new configuration
So here is how it works. There is a new special argument keyword $LANG that will be replaced by the new field “language argument” and the currently set language. Since engines support different languages (or none) and call them different names (e.g. Tesseract expects “por” for the Portuguese, others may expect “pt”) there is another new field called “languages” which should be a map between the language code in the ISO 639-1 and the name of the language of the engine expects, as shown in the screenshot.

Languages combo
To show the languages, there is a new tab in the areas’ editor called Misc (in lack of a better name for a tab that’s holding more stuff in the future) with the languages combo. This combo shows a check on the languages that the currently selected engine recognizes as seen in the screenshot.

There is also a new setting in the preferences dialog with the default language and the first time the application runs, it will assign it to the user’s locale.
One thing must be taken into account: even though Tesseract supports an extensive list of languages, the users must have those packages installed in their distros, otherwise, recognition will of course fail.

To finish, related to my recent job search, I have spent this week in San Francisco getting to know some people from an exciting start-up and despite the jet lag, I managed to finish this release so I can now say that least part of OCRfeeder was designed and developed in California ๐Ÿ˜›

Source tarball
Git
Bugzilla

Playing Angry Birds with a Kinect

Recently I had to use OpenCV in a project inside the Igalia Interactivity and I took the chance to code a little demo I had in my mind for a while: play Angry Birds with a Kinect and using only Free Software.

Here’s the result:


(direct link to video in Vimeo)

How it’s done

The demo uses Skeltrack (the only Free Software skeleton tracking library) to get user’s hands’ positions. The picked hand’s position will be used to move the mouse pointer. This part is the same that is used in the Skeltrack Desktop Control demo.
Once the hand’s position is known, I calculate an area around its point in the original depth image given by GFreenect and then use OpenCV to get the hand’s contours and their convexity defects. An open hand palm will produce very distinguished convexity defects and by counting them I assume the user’s hand palm is open. After this, all that is missing is to tie a detected closed palm to a mouse press and an open palm to a mouse release.

As the video shows, the demo is not polished yet but it shows one of the many possibilities that allying Skeltrack with other computer vision software gives us.

Skeltrack 0.1.10 is out

That’s right, a new version of the world’s first Free Software skeleton tracking library is out.
In every version we try to make Skeltrack more robust and this one is no exception.

Head&Shoulders

We have changed the way the shoulders are inferred. This heuristic now uses a circumference around the user’s head and an arc with which it searches for the shoulders.
Since we like to keep giving developers the ability to tweak the algorithm’s parameters, we had to change the properties related to the shoulders. We should probably improve the documentation with a visual explanation of how those properties work but meanwhile you can check the properties’ documentation.

Centering Joints

Another issue we had was that the extremas we initially calculate result in e.g. the point at tip of the a finger (for a hand joint) or the top of the head. This was not an issue specifically but it might result in more unstable joints. For example, the Kinect device in particular might give blind spots in very bushy hair which would result in the head joint jittering more than usual.
To fix this, we calculate the average of points around an extrema and assign it with that value. The radius of the sphere surrounding an extrema that is used to calculate this average can be controlled by using the extrema-sphere-radius property. Thus, if this behavior is not desired, this feature can be turned off just by simply assigning a 0 to this property.

Here is a couple of pictures describing this issue:

Picture of Skeltrack's test without averaged extremas
Without the averaged extremas (extrema-sphere-radius set to 0)
Picture of Skeltrack's test with averaged extremas
With the averaged extremas (extrema-sphere-radius set to 300)

Vertical Kinect

Due to a project that Igalia Interactivity has been working on, we had to use the Kinect in a vertical stance. By doing this we discovered a small bug that prevented Skeltrack to be used with a vertical depth image. This is corrected in this 0.1.10 version and while fixing it, we found out that it seems the other skeleton tracking alternatives also do not support the Kinect in a vertical stance; this might mean that if you want to use skeleton tracking with the Kinect vertically, your only choice is either to use Skeltrack or to convince Microsoft or PrimeSense to fix their solutions for you ๐Ÿ™‚

Picture of Skeltrack's test example using a Kinect in a vertical stance
Skeltrack using a Kinect in a vertical stance

Last but not least, the function skeltrack_skeleton_new was returning a GObject instance by mistake. We have corrected that and it now returns a pointer to SkeltrackSkeleton as expected.

Special thanks to Iago, our intern at the Igalia Interactivity team, for coding most of these nifty features.

Be sure to clone Skeltrack at GitHub and read the docs, you are welcome to participate in its development.