bilinear interp. supports complex types

in line with cubic etc.

TODO

@@ -1,17 +1,3 @@
-- try:
-
-	$ ./test_resample.py TestResample.test_reduce
-	  File "./test_resample.py", line 129, in test_reduce
-    	self.assertLess(d, 5)
-	AssertionError: 147.0 not less than 5
-
-  affine bicubic != reduce cubic
-
-  displacement error, I guess?
-
-  yes, reduceh output should move one to the right
-
-- need more tests for reduce, test every kernel plus every numeric type
 
 - try orc version of reducev? and shrinkv? maybe shrinkh?
 

libvips/resample/interpolate.c

@@ -508,6 +508,8 @@ G_DEFINE_TYPE( VipsInterpolateBilinear, vips_interpolate_bilinear,
 	case VIPS_FORMAT_INT: 	FLOAT( int );  break;  \
 	case VIPS_FORMAT_FLOAT: FLOAT( float ); break;  \
 	case VIPS_FORMAT_DOUBLE:FLOAT( double ); break;  \
+	case VIPS_FORMAT_COMPLEX: FLOAT( float ); break;  \
+	case VIPS_FORMAT_DPCOMPLEX:FLOAT( double ); break;  \
 	default: \
 		g_assert( FALSE ); \
 	} \
@@ -521,7 +523,8 @@ vips_interpolate_bilinear_interpolate( VipsInterpolate *interpolate,
 	 */
 	const int ps = VIPS_IMAGE_SIZEOF_PEL( in->im );
 	const int ls = VIPS_REGION_LSKIP( in );
-	const int b = in->im->Bands;
+	const int b = in->im->Bands *
+		(vips_band_format_iscomplex( in->im->BandFmt ) ?  2 : 1);
 
 	const int ix = (int) x;
 	const int iy = (int) y;

test/test_resample.py

@@ -116,8 +116,13 @@ class TestResample(unittest.TestCase):
 
     def test_reduce(self):
         im = Vips.Image.new_from_file("images/IMG_4618.jpg")
+        # cast down to 0-127, the smallest range, so we aren't messed up by
+        # clipping
+        im = im.cast(Vips.BandFormat.CHAR)
         bicubic = Vips.Interpolate.new("bicubic")
-        
+        bilinear = Vips.Interpolate.new("bilinear")
+        nearest = Vips.Interpolate.new("nearest")
+
         for fac in [1, 1.1, 1.5, 1.999]:
             for fmt in all_formats:
                 x = im.cast(fmt)
@@ -126,7 +131,26 @@ class TestResample(unittest.TestCase):
                              interpolate = bicubic,
                              oarea = [0, 0, x.width / fac, x.height / fac])
                 d = (r - a).abs().max()
-                self.assertLess(d, 5)
+                self.assertLess(d, 10)
+
+        for fac in [1, 1.1, 1.5, 1.999]:
+            for fmt in all_formats:
+                x = im.cast(fmt)
+                r = x.reduce(fac, fac, kernel = "linear")
+                a = x.affine([1.0 / fac, 0, 0, 1.0 / fac], 
+                             interpolate = bilinear,
+                             oarea = [0, 0, x.width / fac, x.height / fac])
+                d = (r - a).abs().max()
+                self.assertLess(d, 10)
+
+        # for other kernels, just see if avg looks about right
+        for fac in [1, 1.1, 1.5, 1.999]:
+            for fmt in all_formats:
+                for kernel in ["nearest", "lanczos2", "lanczos3"]:
+                    x = im.cast(fmt)
+                    r = x.reduce(fac, fac, kernel = kernel)
+                    d = abs(r.avg() - im.avg())
+                    self.assertLess(d, 2)
 
     def test_resize(self):
         im = Vips.Image.new_from_file("images/IMG_4618.jpg")