From 76ff37a9dc3c16d5c1751a2263d54f0efe1d2108 Mon Sep 17 00:00:00 2001
From: Nathan Perkins <nathan@maxmo.net>
Date: Wed, 22 Apr 2015 09:05:04 -0400
Subject: [PATCH] Implement MW-PCAG.

---
 mwpcag.m       | 17 +++++++++++++++++
 mwpcag_block.m | 40 ++++++++++++++++++++++++++++++++++++++++
 run_script.m   |  7 +++++++
 3 files changed, 64 insertions(+)
 create mode 100644 mwpcag.m
 create mode 100644 mwpcag_block.m

diff --git a/mwpcag.m b/mwpcag.m
new file mode 100644
index 0000000..08605e7
--- /dev/null
+++ b/mwpcag.m
@@ -0,0 +1,17 @@
+function im_result = mwpcag(img)
+%MWPCAG Perform the MW-PCAG algorithm on img.
+
+height = size(img, 1);
+width = size(img, 2);
+
+im_result = zeros(height, width);
+for sz = 9:2:15
+    % run MW-PCAG
+    cb = @(block) mwpcag_block(block, floor((sz-2)^2*0.1), floor(sz*sz*0.45));
+    r = blockproc(img, [sz sz], cb, 'PadPartialBlocks', true, 'PadMethod', 'symmetric');
+    
+    % MAX
+    im_result = max(im_result, r(1:height, 1:width));
+end
+
+end
diff --git a/mwpcag_block.m b/mwpcag_block.m
new file mode 100644
index 0000000..64be95a
--- /dev/null
+++ b/mwpcag_block.m
@@ -0,0 +1,40 @@
+function px = mwpcag_block(block_struct, min_size, max_size)
+%MWPCAG_BLOCK Perform the MW-PCAG algorithm on img
+
+% gap between pixels
+diff_num = 2;
+
+% square odd dimension
+block_size = size(block_struct.data);
+channels = size(block_struct.data, 3);
+
+vals = reshape(block_struct.data, [], channels);
+[~, p_sc, p_la] = pca(vals, 'Algorithm', 'svd', 'Centered', false);
+
+ret = zeros([size(vals, 1) 1]);
+
+p_nm = size(p_sc, 2);
+for c = 1:p_nm
+    [s, s_i] = sort(p_sc(:, c));
+    
+    % forward
+    [fm, fm_i] = max(diff_span(s(min_size:max_size), diff_num));
+    
+    % backward
+    [bm, bm_i] = max(diff_span(s(end - max_size:end - min_size), diff_num));
+    
+    % largest
+    if fm > bm
+        fm_i = min_size - 1 + fm_i;
+        ret(s_i(1:fm_i)) = ret(s_i(1:fm_i)) + (fm * p_la(c));
+    else
+        bm_i = numel(s) - max_size - 1 + bm_i + diff_num;
+        ret(s_i(bm_i:end)) = ret(s_i(bm_i:end)) + (bm * p_la(c));
+    end
+end
+
+% normalize
+% restore shape
+px = reshape(ret / sum(p_la), block_size(1), block_size(2));
+
+end
diff --git a/run_script.m b/run_script.m
index 9bce466..0fb7470 100644
--- a/run_script.m
+++ b/run_script.m
@@ -90,6 +90,13 @@ function run_script(scene_file)
         save(fname, 'img_pcag');
     end
 
+    % MW-PCAG
+    fname = sprintf('output/%s-%d-mwpcag.mat', scene_file, j);
+    if ~exist(fname, 'file')
+        img_mwpcag = mwpcag(img);
+        save(fname, 'img_mwpcag');
+    end
+
     % KNNA
     fname = sprintf('output/%s-%d-knna.mat', scene_file, j);
     if ~exist(fname, 'file')