[JdeRobot] Compressed Images

[Roberto Calvo]

Hello all,

I just merged the 'cif' (Compressed Image Feature) branch to the master
in JdeRobot repository. The goal is that images are going compressed in
order to reduce the latency that we have in WIFI/Wire environments. For
local environments is not so useful.

This involves some changes in the 'image' interface [1]. Firstable, we
have a new method to implement by server images to know what kind of
formats are supported in that server (getImageFormat() method). And
second, the getImageData() method expect one parameter to define the
format of the image. Typically it could be RGB8, RGB8_Z, DEPTH8_16,
DEPTH8_16_Z.  CameraServer and OpenniServer have been modified to
provide regular and compressed images.

For the clients it's even more easy. Just use cameraClient class from
paralellice package to get the images from a server. cameraClient is the
responsible to negotiate the format of the image, and whenever possible
the library will try to use compressed images.

Also I added a checksum field in the interface to save the checksum of
the image and send it with the image. So, the client can check the
integrity of the image.

Some numbers with 320x240 compressed images:

 - Reduce the color-image size in 98% in dark environments
 - Reduce the color-image size in in 87% in light environments
 - Compress Time: 10 milliseconds per image
 - md5sum Time: 300 microseconds per image

I attached some interesting plos as well. Soon I'll document this
feature in the wiki.

If you notice that some component or library doesn't work correctly,
please let me know.

Best,

[1]
https://github.com/RoboticsURJC/JdeRobot/blob/master/src/stable/interfaces/slice/jderobot/image.ice


-- 
Roberto Calvo Palomino        | Robotics Lab (GSyC) 
R&D Android Mobile Engineer   | Universidad Rey Juan Carlos

Twitter: @rocapal 
Linkedin: http://www.linkedin.com/in/rocapal
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