Changeset 20566

Timestamp:

Nov 6, 2008, 1:36:20 PM (18 years ago)

Author:

Paul Price

Message:

When convolving using an FFT, make the size of images that are FFT-ed
an integer power of two. This has a strong positive effect on the
speed.

File:

• trunk/psLib/src/fft/psImageFFT.c (modified) (4 diffs)

trunk/psLib/src/fft/psImageFFT.c

@@ -6 +6 @@
 /// @author Robert DeSonia, MHPCC
 ///
-/// @version $Revision: 1.27 $ $Name: not supported by cvs2svn $
-/// @date $Date: 2008-08-14 03:23:13 $
+/// @version $Revision: 1.28 $ $Name: not supported by cvs2svn $
+/// @date $Date: 2008-11-06 23:36:20 $
 ///
 /// Copyright 2004-2005 Maui High Performance Computing Center, University of Hawaii
@@ -20 +20 @@
 #include <complex.h>
 #include <fftw3.h>
+#include <limits.h>
 #include <pthread.h>
 
@@ -32 +33 @@
 #include "psFFT.h"
 #include "psImageFFT.h"
+
+#define FFT_CONVOLVE_BINARY_SIZE 1               // Scale up to next binary size
 
 // Lock FFTW access
@@ -340 +343 @@
         return NULL;
     }
+
     int paddedCols = numCols + PS_MAX(-xMin, xMax); // Number of columns in padded image
     int paddedRows = numRows + PS_MAX(-yMin, yMax); // Number of rows in padded image
+
+#if CONVOLVE_FFT_BINARY_SIZE
+    // Make the size an integer power of two
+    {
+        int twoCols, twoRows;           // Size that is a factor of two
+        for (twoCols = 1; twoCols <= paddedCols && twoCols < INT_MAX - 1; twoCols <<= 1); // No action
+        for (twoRows = 1; twoRows <= paddedRows && twoRows < INT_MAX - 1; twoRows <<= 1); // No action
+        if (paddedCols > twoCols || paddedRows > twoRows) {
+            psError(PS_ERR_BAD_PARAMETER_SIZE, true, "Unable to scale size (%dx%d) up to factor of two",
+                    paddedCols, paddedRows);
+            return NULL;
+        }
+        paddedCols = twoCols;
+        paddedRows = twoRows;
+    }
+#endif
+
     int numPadded = paddedCols * paddedRows; // Number of pixels in padded image