
gular arrangement as size fo type III and IV (type 
V). 
Whenever possible those parameters were auto-
matically extracted by image analysis. See below. 
2.2  Image Search & Retrieval Applica-
tion 
Search and retrieval application built is an MPQF 
query processor. The software was limited to basic 
capabilities and did not provide yet CBIR functions 
Query-by-Image formulation: According ISO-
15938-12:2008, the query-by-image is a combina-
tion of different condition expressions such as Que-
ryByMedia,  QueryByDescription,  QueryByROI  and 
SpatialQuery.  
All these MPQF’s condition types are based in 
the provision of an example (image, image region or 
image metadata description) expressing user infor-
mation (see above IR system metadata). These con-
dition types are selected or combined in order to 
return the best results. 
1.  QueryByMedia 
Query-by-image (or simply query-by-example) 
similarly searches is a content based image retrieval 
(CBIR) technique (Lux et al., 2008)  expressing user 
information with one or more example digital ob-
jects (e.g. an image file). Low-level features descrip-
tion instead of the example object bit stream is also 
considered query-by-example, in MPQF these two 
situations are differentiated, naming QueryByMedia 
to the first case (the digital media itself) and Query-
ByDescription the second one. In the first case is the 
query processor who decides which features to ex-
tract and use, and in the second case is the requester 
who perform the feature extraction and selection. 
The MPQF’s QueryByMedia type offers multiple 
possibilities to refer to the example media, as just 
including the media identifier (a locator such as an 
URL pointing to an external or internal resource) or 
directly embedding the image bit stream in Base64 
encoding within the XML Query (see example in 
Code 1). 
When the QueryByMedia type is used, it is up to 
the query processor to extract the proper low-level 
features to perform a similarity search over the in-
dex. MPQF does not specify which parameters or 
algorithms must be applied. In our case image analy-
sis automatic extraction is done whenever possible 
2.  QueryByDescription 
QueryByMedia and QueryByDescription are the 
fundamental operations of MPFQ and represent the 
query-by-example paradigm. The individual dif-
ference lies in the used sample data. The QueryBy-
Media query type uses a media sample such as im-
age as a key for search, whereas QueryByDescrip-
tion allows querying on the basis of an XML-based 
description. 
For the purpose of the work described in this pa-
per, we were using the QueryByDescription type to 
communicate to the server the specific metadata 
related to the example image fixed by the requester 
(e.g. pit size, distance and regularity of normal 
round pits, detection of stellate or papillary images, 
so on and so forth). These metadata were extracted 
whenever possible (by image analysis extraction) 
before submitting the query to the generic MPQF 
query processor.  
3.  QueryByROI 
The MPQF’s QueryByROI type extends the Que-
ryByMedia type and describes a query operation that 
takes an example digital image as input and allows 
the specification of a region of interest. During the 
evaluation of this query type the region of interest is 
required to be considered for search. A region is 
defined by the IntegerMatrixType which allows 
the specification of a list of positive integer values 
describing individual points. The amount of neces-
sary integer values per point is defined by the dim 
(dimension) attribute of the IntegerMatrixType type. 
If the dim attribute is set to two then two successive 
integer values specify one point in 2D space. The 
individual points define the region where for in-
stance for 2D, three points identify a triangle, four 
points a rectangular, and so on. The order of the 
individual points is contraclockwise. Code 2 gives 
an example of QueryByROI using a square bound-
ing box. 
For the purpose of the work described in this pa-
per, we were using the QueryByROI type to offer to 
users the (optional) functionality to refine their 
query-by-image searches by specifying a region of 
interest (only a 2D square bounding box at the mo-
ment).  
-The query processor only needed to crop the image 
according to the region specified and processed a 
conventional  QueryByMedia evaluation. This way, 
the resulting images will be similar to the region 
specified.  
-Furthermore, we considered to allow searching for 
“images containing region/s similar to the given 
one” and (if possible) to retrieve also the coordinates 
of these region/s. In despite of the fact that MPQF 
offers
 enough expressivity to formulate such a query, 
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