It’s been more than a year since we made a release, so there have been lots of changes, fixes and new features. Most important of all is the integration of the SIMPLE descriptor, a local feature that works extremely well for content based image retrieval. This has been done with a lot of help from Nektarios Anagnostopoulos and Savvas Chatzichristofis!
Besides that we switched to OpenCV for SURF and SIFT extraction, added numerous bug fixes, updated Lucene to 4.10.2 and much more. Best you give it a try.
I’ve just uploaded LIRE 0.9.4 beta to the Google Code downloads page. This is an intermediate release that reflects several changes within the SVN trunk. Basically I put it online as there are many, many bugs solved in this one and it’s performing much, much faster than the 0.9.3 release. If you want to get the latest version I’d recommend to stick to the SVN. However, currently I’m changing a lot of feature serialization methods, so there’s no guarantee that an index created with 0.9.4 beta will work out with any newer version. Note also that the release does not work with older indexes 😉
Major changes include, but are not limited to:
New features: PHOG, local binary patterns and binary patterns pyramid
Parallel indexing: a producer-consumer based indexing application that makes heavy use of available CPU cores. On a current Intel Core i7 or considerably large Intel Xeon system it is able to reduce extraction to a marginal overhead to disk I/O.
Intermediate byte based feature data files: a new way to extract features in a distributed way
In-memory cached ImageSearcher: as long as there is enough memory all linear searching is done in memory without much disk I/O (cp. class GenericFastImageSearcher and set caching to true)
Approximate indexing based on hashing: tests with 1.5 million led to search time < 300ms (cp. GenericDocumentBuilder with hashing set to true and BitSamplingImageSearcher)
Footprint of many global descriptors has been significantly reduced. Examples: EdgeHistogram 40 bytes, ColorLayout 504 bytes, FCTH 96 bytes, …
New unit test for benchmarking features on the UCID data set.
The current LireDemo 0.9.4 beta release features a new indexing routine, which is much faster than the old one. It’s based on the producer-consumer principle and makes — hopefully — optimal use of I/O and up to 8 cores of a system. Moreover, the new PHOG feature implementation is included and you can give it a try. Furthermore JCD, FCTH and CEDD got a more compact representation of their descriptors and use much less storage space now. Several small changes include parameter tuning on several descriptors and so on. All the changes have been documented in the CHANGES.txt file in the SVN.
In the current SVN version three global features have been re-visited in terms of serialization. This was necessary as the index of the web demo with 300k images already exceed 1.5 GB.
This significant reduction in space leads to (i) smaller indexes, (ii) reduced I/O time, and (iii) therefore, to faster search.
How was this done? Basically it’s clever organization of bytes. In the case of JCD the histogram has 168 entries, each in [0,127], so basically half a byte.Therefore, you can stuff 2 of these values into one byte, but you have to take care of the fact, that Java only supports bit-wise operations on ints and bytes are signed. So the trick is to create an integer in [0, 2^8-1] and then subtract 128 to get it into byte range. The inverse is done for reading. The rest is common bit shifting.
The code can be seen either in the JCD.java file in the SVN, or in the snippet at pastebin.com for your convenience.
A new web based LIRE demo is online. Within this demo you are able to search in an index of 300.000 images from the MIRFLICKR data set. Currently online queries from within the index are allowed, so no custom query images can be uploaded. The backend is plain LIRE, so there’s no search server and alike, and it’s the current SVN version. Search is done based on hashing, so the results are approximate, but they are immediately there. Also it’s just a selection of global features, but it’s enough to get the idea. The image below shows the result of two example searches.
With the implementation of the PHOG descriptor I came around the situation that no well-performing Canny Edge Detector in pure Java was available. “Pure” in my case means, that it just takes a Java BufferedImage instance and computes the edges. Therefore, I had to implement my own
As a result there is now a “simple implementation” available as part of LIRE. It takes a BufferedImage and returns another BufferedImage, which contains all the edges as black pixels, while the non-edges are white. Thresholds can be changed and the blurring filter using for preprocessing can be changed in code. Usage is dead simple:
BufferedImage in = ImageIO.read(new File("testdata/wang-1000/128.jpg"));
CannyEdgeDetector ced = new CannyEdgeDetector(in, 40, 80);
ImageIO.write(ced.filter(), "png", new File("out.png"));
People lately asked whether LIRE can do more than linear search and I always answered: Yes, it should … but you know I never tried. But: Finally I came around to index the MIR-FLICKR data set and some of my Flickr-crawled photos and ended up with an index of 1,443,613 images. I used CEDD as main feature and a hashing algorithm to put multiple hashes per images into Lucene — to be interpreted as words. By tuning similarity, employing a Boolean query, and adding a re-rank step I ended up with a pretty decent approximate retrieval scheme, which is much faster and does not loose too many images on the way, which means the method has an acceptable recall. The image below shows the numbers along with a sample query. Linear search took more than a minute, while the hashing based approach did (nearly) the same thing in less than a second. Note that this is just a sequential, straight forward approach, so no optimization has been done to the performance. Also the hashing approach has not yet been investigated in detail, i.e. there are some parameters that still need some tuning … but let’s say it’s a step into the right direction.
I just uploaded Lire 0.9.3 to the all new Google Code page. This is the first version with full support for Lucene 4.0. Run time and memory performance are comparable to the version using Lucene 3.6. I’ve made several improvements in terms of speed and memory consumption along the way, mostly within the CEDD feature. Also I’ve added two new features:
JointHistogram – a 64 bit RGB color histogram joined with pixel rank in the 8-neighborhood, normalized with max-norm, quantized to [0,127], and JSD for a distance function
Opponent Histogram – a 64 bit histogram utilizing the opponent color space, normalized with max-norm, quantized to [0,127], and JSD for a distance function
Both features are fast in extraction (the second one naturally being faster as it does not investigate the neighborhood) and yield nice, visually very similar results in search. See also the image below showing 4 queries, each with the new features. The first one of a pair is always based on JointHistogram, the second is based on the OpponentHistogram (click ko see full size).
I also changed the Histogram interface to double as the double type is so much faster than float in 64 bit Oracle Java 7 VM. Major bug fix was in the JSD dissimilarity function. So many histograms now turned to use JSD instead of L1, depending on whether they performed better in the SIMPLIcity data set (see TestWang.java in the sources).
Final addition is the Lire-SimpleApplication, which provides two classes for indexing and search with CEDD, ready to compile with all libraries and an Ant build file. This may — hopefully — help those that still seek Java enlightenment 😀
Finally this just leaves to say to all of you: Merry Christmas and a Happy New Year!
I just submitted my code to the SVN and created a download for Lire 0.9.3_alpha. This version features support for Lucene 4.0, which changed quite a bit in its API. I did not have the time to test the Lucene 3.6 version against the new one, so I actually don’t know which one is faster. I hope the new one, but I fear the old one 😉
This is a pre-release for Lire for Lucene 4.0
Global features (like CEDD, FCTH, ColorLayout, AutoColorCorrelogram and alike) have been tested and considered working. Filters, like the ReRankFilter and the LSAFilter also work. The image shows a search for 10 images with ColorLayout and the results of re-ranking the result list with (i) CEDD and (ii) LSA. Visual words (local features), metric indexes and hashing have not been touched yet, beside making it compile, so I strongly recommend not to use them. However, due to a new weighting approach I assume that the visual word implementation based on Lucene 4.0 will — as soon as it is done — be much better in terms for retrieval performance.
I just uploaded version 0.9.2 of Lire and LireDemo to Google Code. Yes, Google Code! I also migrated (more or less in a under cover action some month ago) the SVN trunk to Google Code and will move on with development there. Main reasons were that ads were getting more and more aggressive over at sf.net and the interface of a Google Code project is so much cleaner and easier to handle from a project manager point of view.
Lire 0.9.2 fixes two bugs in KMeans and GenericImageSearcher. Both were critical. The KMeans fix allows now for the use of the bag of visual words approach. The GenericImageSearcher fix makes search much faster.