Processing: a programming language for generative art

Recently I got some interest about generative art. As computer scientist who has interest about art but no drawing skills, it sounds interesting to being able to generate art by coding. Especially geometric and abstract art looks quite mesmerizing:


To do so, I found that several artists are using “Processing” which is according to the website: “a flexible software sketchbook and a language for learning how to code within the context of the visual arts”. Some simple tutorials are available in the website, and after few minutes, I was already able to generate some simple shape.

To go further, I looked for some books and found a nice one written by Matt Pearson and published by Manning Publication named: Generative Art – A practical guide using Processing. And the nice thing is that the code used in the book is open source and anyone can download and use it.


Using Flickr images for 3D reconstruction

At the Electronic Imaging symposium of 2013, Steve Seitz from Washington University and Google presented a very interesting keynote entitled “a trillion photos”.

The principle is to exploit the millions of images found in databases such as Flickr. The aim of the project Building Rome in a Day is to harvest images from Flickr by simply typing the keywords “Rome” or “Venice”. Many images are unusable because they can not be matched with other images  – such as pictures of a restaurant, of a family, etc. On the other hand, the most touristic places such as “San Marco” are taken in picture from many different angles. By using a standard processing stream such as SIFT + RANSAC + FLANN it is possible to match the images and then to do the 3D reconstruction.

In this video , the pyramids represent the estimated shooting positions. The reconstruction was made by ​​using 14,079 pictures. The reconstruction of Venice is made by ​​using 250,000 images, 496 computing cores. 27h are necessary for matching and 38h for reconstruction.

Understanding how bags of visual words work




How the bags of visual words works ?

Here is the principle in 4 simple steps :




Handwritten digits recognition based on neural networks

During summer 2012 and summer 2013 I supervised two master internship about handwritten digit recognition at Gestform digitizing company. The first one was about basic notions for reading, in a simple case, a handwritten digit and the second one was about segmentation of digits.

Here is an example of what we want to do :

HandwrittenDigitsTwo things are done here : 1) recognizing which part of the text contain digits or not and then 2) reading the digits. Almost the same tools are used for part 1 and 2.

Which part of the text contain digits ?

First, we try to segment the text line by line. Several algorithms can be apply for doing that, here a simple one is used : RLSA.

RLSAThen each connected component are extracted and analyzed in order to classified it as digit or non-digit.

CCCC2As we can see, before extracting connected components some preprocessing should be done such as morphological mathematics (dilatation and erosion) because some parts of digits are cut.

In order to extract the features homogeneously, some preprocessing are applied before feature extraction in order to normalize the features : correction the slope and the angle of the digit.

Then many features are extracted such as :

  • Hu invariant moments
  • Projection histograms
  • Profile histograms
  • Intersection with horizontal lines
  • Position of holes
  • Extremities
  • Junction points

Profile histogram


Projection histogram


Intersection with horizontal and vertical lines

They are all concatenated into one vector of 124 dimensions. Another vector is build from Freeman chain code (an histogram of 128 dimensions).


Freeman chain code

After extracting features, two neural networks are used in order to classify connected component as digit or non-digit. The first one have 124 inputs and the second one 128, each have 2 output : D (digit) or R (reject or non-digit). Many example have to be used in order to train the classifier (around 10 000 for each class).


Reading the digits

Here, the same features and neural network are used, but instead of 2 classes (digit / non-digit) 10 classes are used (0,1,2,3,4,5,6,7,8,9).

You can download training examples here. Some examples of 6 digits :



Correcting some classification errors

Many digits are touching others and are classified as R. So we introduced a new class. as “DD” (double digit). Furthermore, by using the sequences it is possible to correct some errors. By example, if you are looking for a 5 digit postal code it is possible to change a result such as : RRDDDRDRR as RRDDDDDRR or also filtering noise : RRRRRRDRRRR -> RRRRRRRRRRR. In order to do this HMM is used. Here is a HMM designed for postal code with D (digit) DD (double digits) and R (reject / non-digit) classes :


Double digits segmentation

In order to do double digits segmentation, the “drop fall” algorithm is used.
dropFallThe drop fall algorithm can be seen as if a drop of water is sliding along the digits. 4 drop fall can be done depending if the starting point is set up/left, up/right, down/right or down/left. Then, in order to chose the best segmentation the digits are recognized by the neural network, the couple of digits with the best recognition rate is kept.


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How to create a word cloud from text files with R

Here is the result of the creation of word cloud applied to 100 scientific papers from ICDAR 2013 conference :wordcloud

Text mining is a useful tool for making an overview of subjects or important words in a text collection such as website, books, articles, etc.

Creating a word cloud from text files with R is easy. The first thing to do is to install R and two packages : “tm” and “wordcloud” (maybe these package will need others packages, you just have to follow R instructions). Then,  put all the text files you want to analyze in the same directory, and write the following code in R :


# Loading libraries

# Define the folder where the text files are
a <-Corpus(DirSource("C:/MyPath/FolderContaining/TxtFiles"), readerControl = list(language="lat"))

# Preprocessing text
a <- tm_map(a, removeNumbers) # Not necessary if numbers are important for you
a <- tm_map(a, removePunctuation)
a <- tm_map(a , stripWhitespace)
a <- tm_map(a, tolower)
# Stopwords are words such as "we" "the" "and" "so", etc. You can add your own words to the list
a <- tm_map(a, removeWords, c(stopwords("english"), "can", "also", "may"))
# a <- tm_map(a, stemDocument, language = "english") # You can also do steamming if you want

# Computing the term document matrix
tdm <- TermDocumentMatrix(a)

# Transforming data for wordcloud
m <- as.matrix(tdm)
myNames <- names(v)

# Making and displaying the cloud
wordcloud(d$word, d$freq, min.freq=150)