diff trunk/matlab/bmm/carfac/MultiScaleSmooth.m @ 516:68c15d43fcc8

Added MATLAB code for Lyon's CAR-FAC filter cascade.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trunk/matlab/bmm/carfac/MultiScaleSmooth.m	Wed Feb 15 21:26:40 2012 +0000
@@ -0,0 +1,70 @@
+% Copyright 2012, Google, Inc.
+% Author: Richard F. Lyon
+%
+% This Matlab file is part of an implementation of Lyon's cochlear model:
+% "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+% to supplement Lyon's upcoming book "Human and Machine Hearing"
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%     http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+
+function MultiScaleSmooth(waves, n_scales)
+% function MultiScaleSmooth(waves, n_scales)
+%
+% Let's take columns as waveforms, and smooth them to different scales;
+% these inputs can be carfac NAPs, for example, and the peaks of the
+% smoothed versions can be used as trigger events, even tracking back
+% to less-smoothed versions.
+% And we'll deciamte 2:1 at every other smoothing.
+%
+% Until we decide what we want, we'll just plot things, one plot per scale.
+
+fig_offset1 = 10;
+fig_offset2 = 30;
+fig_offset3 = 50;
+
+if nargin < 2
+  n_scales = 20;
+end
+
+smoothed = waves;
+
+for scale_no = 1:n_scales
+
+  if mod(scale_no, 2) == 1
+    newsmoothed = filter([1, 1]/2, 1, smoothed);
+    diffsmoothed = max(0, smoothed - newsmoothed);
+    smoothed = newsmoothed;
+  else
+    newsmoothed = filter([1, 2, 1]/4, 1, smoothed);
+    diffsmoothed = max(0, smoothed - newsmoothed);
+    smoothed = newsmoothed(1:2:end, :);
+  end
+
+  figure(scale_no + fig_offset1)
+  imagesc(smoothed')
+
+  figure(scale_no + fig_offset2)
+  plot(mean(smoothed, 2));
+
+  drawnow
+  pause(1)
+
+end
+
+
+function waves = deskew(waves)
+
+for col = 1:size(waves, 2)
+  waves(1:(end-col+1), col) = waves(col:end, col);
+end
+