T 1569/09 17-12-2013

Reasons for the Decision

1. Main request: admission (Article 13(1) RPBA)

The present main request was filed in reaction to the board's indication given in the communication and thus constitutes an amendment to the appellant's case within the meaning of Article 13(1) RPBA. It corresponds to the first auxiliary request filed with the statement of grounds of appeal and therefore does not increase the complexity of the case. It allowed the board to focus on the essential objections raised in the decision under appeal and was therefore admitted into the appeal proceedings.

2. Main request: amendments (Article 123(2) EPC)

2.1 Claim 1 of the main request is based on originally filed claim 1. The selection of the number of quantisation bits in accordance with the magnitude of the influence of the quantisation errors on restored excluded pixels of lower hierarchy is disclosed on page 28, second full paragraph, of the application as filed. The number of quantisation bits used in the quantisation step in higher and lower hierarchies is disclosed for instance on page 19, second full paragraph, or page 28, second full paragraph, of the application as filed.

2.2 In the decision under appeal the examining division objected in this respect that in the application as filed there was no teaching or clear disclosure of the selection of the number of quantisation bits unless the selection was interpreted as a 4-fold finer quantisation step in the higher hierarchy.

2.3 The board, however, notes that the original description discloses on page 28, second full paragraph, that the number of quantisation bits (1, 4, 16) is selected in consideration of the influence of the quantisation errors in the higher hierarchy (level) on the restored pixel value in the lower hierarchy. This influence of the quantisation errors is analysed on page 25, line 5 to page 29, line 17 and shown in figure 6 in table form (see page 28, first paragraph). The quantisation errors contribute with an absolute factor of 1 or 4 to the restored pixel values in the lower hierarchy (and with an absolute factor of 16 to the next lower hierarchy). The factors 1 and 4 result from the number of pixels of the lower hierarchy used in generating the pixels of the higher hierarchy when forming the average (see equations (1) and (2) on page 17) and used in the corresponding restoring of excluded pixel data (see equations (3) and (4) on pages 22 and 23 and equations (7) to (10) on pages 26 and 27). Thus, the specific values of 1, 4 and 16 bits discussed on page 28, second full paragraph, are the result of a specific teaching disclosed in relation to the embodiment of the application.

2.4 In view of the above the board finds that the objection under Article 123(2) EPC raised in the decision under appeal is not valid against present (amended) claim 1.

3. Main request: clarity (Article 84 EPC 1973)

3.1 In the decision under appeal the examining division also objected that there was no clear disclosure of how the number of quantisation bits could be selected in accordance with the number of hierarchies and the number of pixels used in generating the higher hierarchy.

3.2 Present claim 1, however, now specifies that the selection of the number of quantisation bits is made "in accordance with the magnitude of the influence of the quantisation errors at that hierarchy on the excluded pixel of the lower hierarchy when restored using the pixel data of that hierarchy". Claim 1 also specifies that this magnitude is dependent on the number of pixels of the lower hierarchy used in generating each pixel of that hierarchy. Taking into account the relevant teaching of the application (see section 2.3 above) the relationship between the number of quantisation bits in the different hierarchies is clear.

3.3 In view of the above the board finds that the objection under Article 84 EPC raised in the decision under appeal is not valid against present (amended) claim 1.

4. Inventive step (Article 56 EPC 1973)

4.1 It is undisputed that the "Reduced-Sum Pyramid" method disclosed in section II.B of D1 is an appropriate starting point for the assessment of inventive step.

4.2 According to that method, hierarchy n is the original image and hierarchy k-1 is formed from hierarchy k (0 < k <= n) by calculating, for each spatially contiguous, non-overlapping block of 2x2 nodes at hierarchy k the sum of the node values in the block. Subsequently, one of the 2x2 nodes is dropped. In the "Reduced-Sum Pyramid" of D1 there is neither an averaging step nor a quantisation step. The number of bits used in the "Reduced-Sum Pyramid" method at any hierarchy k is dependent on the number of bits used for the values of the original image (hierarchy n) and the level of roundoff error which is accepted in the hierarchies k != n. If roundoff errors are not to be introduced, the values at hierarchy k require two more bits than those at hierarchy k-1.

4.3 The "Reduced-Sum Pyramid" specifically addresses a data expansion problem of a "Mean Pyramid" approach (see section II.A of D1) in which for each spatially contiguous, non-overlapping block of 2x2 nodes at hierarchy k the average of the node values in the block is calculated to form hierarchy k-1. The data expansion problem is caused by the forming of hierarchies k != n which results in the total number of nodes in the mean pyramid being larger than the number of pixels in the original image. The "Reduced-Sum Pyramid" avoids the data expansion problem by dropping one of the 2x2 nodes in each block. Thus an averaging step would be contrary to the teaching of the "Reduced-Sum Pyramid" approach as it would mean returning to the "Mean Pyramid" approach.

4.4 In this context the board notes that extra bits per node are needed in both the "Mean Pyramid" and "Reduced-Sum Pyramid" approach: in the former to accurately record the average and in the latter to avoid roundoff errors. In the "Mean Pyramid" approach, these extra bits can be avoided by rounding off the node values to the same resolution as the original image.

4.5 The examining division identified three distinguishing features over the "Reduced-Sum Pyramid" approach in D1, one of which was that the quantisation step quantised the data in higher hierarchies more finely (see point VIII above). But the examining division considered that there was no clear disclosure in the application as to how the number of quantisation bits could be selected (see also section 3 above) and that, in view of D3, finer quantisation, in particular a

4-fold finer quantisation step in each level, would be an obvious choice. Based on these considerations the examining division held that it was at least obvious from D1 that the sum of pixel values calculated in the "Reduced-Sum Pyramid" approach in D1 could be divided by the number of pixels, thereby yielding the mean pixel value and that consequently "the technique of averaging and excluding" was obvious (emphasis by the board, see point 2.I.1.c.1 of the decision under appeal).

4.6 Present claim 1 comprises the feature that the number of quantisation bits used in the quantisation step is selected, for each hierarchy other than the bottom hierarchy, in accordance with the magnitude of the influence of the quantisation errors at that hierarchy on the excluded pixel of the lower hierarchy when restored using the pixel data of that hierarchy, the magnitude of the influence being dependent on the number of pixels of the lower hierarchy used in generating each pixel of that hierarchy. Thus the method of present claim 1 implies a step of analysing the influence of the quantisation errors at that hierarchy on the excluded pixel of the lower hierarchy when restored using the pixel data of that hierarchy. It is clear from the present application that the

4-fold finer quantisation step in each level arises from the particular pyramid scheme disclosed in the present application (see point 2.3 above). For instance, different values for the influence of the quantisation errors would result if block sizes other than 2x2 were used or if the "Reduced-Sum Pyramid" known from D1 were used for forming the higher hierarchy.

4.7 When forming the "Reduced-Sum Pyramid" in D1 there is no need for quantisation. Quantisation only becomes necessary when compression coding is additionally considered, typically for transmission. In this respect the board agrees with the finding in the decision under appeal that it was well-known that lossy encoding could be performed by means of quantisation and that in any method of hierarchical encoding (such as the different approaches disclosed in D1) the problem of choosing quantisation for the different hierarchical layers presented itself (see point 2.I.1.a.7 of the decision under appeal).

4.8 D3 proposes a modified "Gaussian-Laplacian Pyramid", which is a type of pyramid discussed in section II.F of D1 and is different from the "Mean Pyramid" and the "Reduced-Sum Pyramid". The general statement in D3, point 3.2, that "Quantisation is critical in pyramid schemes, because errors at high levels may be spread down over lower ones" does not disclose which specific quantisation scheme must be chosen for any particular type of pyramid. This general statement implies that finer quantisation is required for higher levels than for lower levels if errors at high levels spread down over lower ones. But the extent to which quantisation must be finer for higher levels needs to be determined separately for each type of pyramid, because the influence of quantisation errors at a high level on the lower levels depends on the particular type of pyramid. In particular, D3 does not discuss if or how the manner in which quantisation errors at high levels may spread down over lower ones is influenced by node dropping if a "Reduced-Sum Pyramid" is used.

4.9 In view of the above the board finds that the objection under Article 56 EPC raised in the decision under appeal is not valid against present (amended) claim 1.

5. Moreover, also in the other documents discussed in the decision under appeal there is no teaching to adopt a quantisation method whereby the number of quantisation bits used for each hierarchy is selected in accordance with the magnitude of the influence of the quantisation errors at that hierarchy on the excluded pixel of the lower hierarchy when restored using the pixel data of that hierarchy. Thus on the basis of claim 1 of the present main request the board finds that the decision under appeal is to be set aside.

5.1 Since the board decided that the decision under appeal is to be set aside on the basis of the appellant's present main request, there is no need for the board to consider the allowability of the appellant's present first and second auxiliary requests.

6. Remittal (Article 111(1) EPC 1973)

6.1 In the present case, in the decision under appeal the examining division decided only on the patentability of the subject-matter of claim 1 of the requests then on file and took no decision on the other independent claims or the dependent claims of the requests then on file. Hence full examination of the application as to patentability requirements has not yet been carried out. Further examination, however, is still necessary since there are, for instance, further independent claims in the present main request. The board sees no reason to go beyond its primary task of examining the contested decision. Full examination as to patentability requirements is the task of the examining division (G 10/93, OJ EPO 1995, 172, point 4 of the Reasons).

6.2 Thus the board considers it appropriate to exercise its discretionary power under Article 111(1) EPC 1973 to remit the case to the department of first instance for further prosecution. Consequently, according to Article 111(2), first sentence, EPC 1973, the examining division is bound by the ratio decidendi of the board on claim 1 of the present main request, in so far as the facts are the same. Therefore it depends on the facts whether and to which extent the ratio decidendi for claim 1 of the present main request applies also to the other claims of that request or to the claims of any further requests which the examining division might admit into the proceedings under Rule 137(3) EPC for example.