Method and device for coding a hierarchized document

A device for coding a hierarchized document comprising, for processing at least one element contained in the document:

• a creating device for creating at least one initial pattern which describes at least structural information of the at least one element, and associating a set of instances of the at least one initial pattern in the hierarchized document with the at least one initial pattern, for creating at least one specialized pattern as a modified copy of the at least one initial pattern, wherein the at least one specialized pattern comprises additional content information common to several instances of the set of instances associated with the at least one initial pattern, and for dividing the set of instances associated with the at least one initial pattern into a set of instances associated with the at least one initial pattern and a set of instances associated with each at least one specialized pattern, wherein, for each initial or specialized pattern, the creating device performs steps of:
• evaluating a first coding cost where the initial or specialized pattern is used for coding a set of instances associated with the initial or specialized pattern,
• evaluating a second coding cost where the initial or specialized pattern is not used for coding the set of instances,
• comparing the evaluated first coding cost and the evaluated second coding cost,
• keeping the initial or specialized pattern in view of coding the at least one element when the first coding cost is lower than the second coding cost, and
• eliminating the initial or specialized pattern from usage in view of coding the at least one element when the first coding cost is higher than the second coding cost;
• and
• coding the at least one element, the kept initial or specialized pattern associated with the at least one element, and pieces of information present in the at least one element and not present in the initial or specialized pattern being also coded,
• wherein in the dividing, the specialized pattern is a copy of the initial pattern to which is added additional content, and
• wherein instances comprising the additional content are associated with the specialized pattern and instances not including the additional content remain associated with the initial pattern.

A non-transitory computer-readable storage medium, storing instructions of a computer program, that makes it possible to implement a method of coding a hierarchized document comprising at least one element, the method comprising the steps of:

• creating at least one initial pattern which describes at least structural information of the at least one element, and associating a set of instances of the at least one initial pattern in the hierarchized document with the at least one initial pattern,
• creating at least one specialized pattern as a modified copy of the at least one initial pattern, wherein the at least one specialized pattern comprises additional content information common to several instances of the set of instances associated with the at least one initial pattern;
• dividing the set of instances associated with the at least one initial pattern into a set of instances associated with the at least one initial pattern and a set of instances associated with each at least one specialized pattern;
• wherein, for each initial or specialized pattern, the method further comprises:
• evaluating a first coding cost where the initial or specialized pattern is used for coding a set of instances associated with the initial or specialized pattern,
• evaluating a second coding cost where the initial or specialized pattern is not used for coding the set of instances associated with the initial or specialized pattern,
• comparing the evaluated first coding cost and the evaluated second coding cost,
• keeping the initial or specialized pattern in view of coding the at least one element when the first coding cost is lower than the second coding cost, and
• eliminating the initial or specialized pattern from usage in view of coding the at least one element when the first coding cost is higher than the second coding cost and
• coding the at least one element, the kept initial or specialized pattern associated with the at least one element, and pieces of information present in the at least one element and not present in the initial or specialized pattern being also coded,
• wherein during the step of dividing, the specialized pattern is a copy of the initial pattern to which is added additional content, and
• wherein instances comprising the additional content are associated with the specialized pattern and instances not including the additional content remain associated with the initial pattern.