[Olena-patches] olena: olena-2.0-791-g3193cca Fix some shortcomings in binary subsampling. This function used to memoryleak and makes an unnecessary heap memory allocation. Moreover, it makes someunnecessary assumptions about the domain of the image (only worked for 2D images with a domainstarting at (0,0)).

* milena/mln/world/binary_2d/subsample.hh: Many fixes. Conflicts: milena/ChangeLog milena/mln/world/binary_2d/subsample.hh --- milena/ChangeLog | 12 +++++++- milena/mln/world/binary_2d/subsample.hh | 51 ++++++++++++++++++++++--------- 2 files changed, 47 insertions(+), 16 deletions(-) diff --git a/milena/ChangeLog b/milena/ChangeLog index 9572039..22bee5f 100644 --- a/milena/ChangeLog +++ b/milena/ChangeLog @@ -1,4 +1,3 @@ -<<<<<<< HEAD 2013-09-02 Roland Levillain &lt;roland(a)lrde.epita.fr&gt; Add parentheses around complex operands of operator `|'. @@ -4770,6 +4769,17 @@ * mln/geom/crop.hh, * mln/geom/crop_without_localization.hh: New. +2013-09-05 Edwin Carlinet &lt;carlinet(a)lrde.epita.fr&gt; + + Fix some shortcomings in binary subsampling. This function used to + memory leak and makes an unnecessary heap memory + allocation. Moreover, it makes some unnecessary assumptions about + the domain of the image (only worked for 2D images with a domain + starting at (0,0)). + + * milena/mln/world/binary_2d/subsample.hh: Many fixes. + + 2012-06-05 Edwin Carlinet &lt;carlinet(a)lrde.epita.fr&gt; Fix issues with loading ascii ppm. diff --git a/milena/mln/world/binary_2d/subsample.hh b/milena/mln/world/binary_2d/subsample.hh index 3ea041a..f6baf6c 100644 --- a/milena/mln/world/binary_2d/subsample.hh +++ b/milena/mln/world/binary_2d/subsample.hh @@ -50,7 +50,18 @@ namespace mln namespace binary_2d { - /// Subsample a Boolean image. + /// \brief Subsample a Boolean image. + /// + /// Subsample a binary image by a factor \p n and return a gray + /// level image by averaging. + /// + /// \[ + /// out(p) = \frac{1}{n^2} \sum_{\epsilon=1}^n input(n.(p+pmin) + + /// \langle \epsilon, 1\rangle ) + /// \] + /// + /// Note that even if the input image does not have its origin + /// at (0,0), the output image does so. /// /// \param[in] input A binary image. /// \param[in] n Linear subsampling coefficient. @@ -75,31 +86,41 @@ namespace mln if (n == 0) return data::convert(int_u8(), input); - const bool** ptr = new const bool*[n]; + const unsigned nrows = input.nrows() / n; const unsigned ncols = input.ncols() / n; - image2d<int_u8> output(nrows, ncols); - - const unsigned delta_row = input.delta_offset(down); - for (unsigned row = 0; row < nrows; ++row) + algebra::vec<2, unsigned int> vmin; + algebra::vec<2, unsigned int> vmax; + vmin[0] = 0; + vmin[1] = 0; + vmax[0] = nrows - 1; + vmax[1] = ncols - 1; + point2d pmin(vmin); + point2d pmax(vmax); + + image2d<int_u8> output(box<point2d>(pmin, pmax)); + dpoint2d dp_row(1, 0); + const unsigned delta_row = input.delta_index(dp_row); + + const bool* origin = &input(input.domain().pmin()); + const bool* line_ptr = origin; + for (unsigned row = 0; row < nrows; ++row, line_ptr += delta_row * n) { - ptr[0] = & input(point2d(n * row, 0)); - for (unsigned i = 1; i < n; ++i) - ptr[i] = ptr[i - 1] + delta_row; - for (unsigned col = 0; col < ncols; ++col) + const bool* ptr = line_ptr; + for (unsigned col = 0; col < ncols; ++col, ptr += n) { unsigned count = 0; for (unsigned i = 0; i < n; ++i) - for (unsigned j = 0; j < n; ++j, ++(ptr[i])) - if (*(ptr[i])) + for (unsigned j = 0; j < n; ++j) + { + if (ptr[delta_row * i + j]) ++count; - output(point2d(row, col)) = count * mln_max(int_u8) / n / n; + } + output.at_(row, col) = count * 255 / n / n; } } - delete[] ptr; - return output; } -- 1.7.10.4