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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