start tests

TODO

@@ -1,11 +1,16 @@
-- write a shrinker that does two 1D shrinks, vertical and horizontal, with
+- strange, try
-  bicubic interpolation
 
-  should be much quicker than affine + bicubic
+	$ vips affine babe.jpg x.v "0.909 0 0 0.909"
+	$ vipsheader x.v
+	x.v: 931x698 uchar, 3 bands, srgb, jpegload
 
-  vips_resize() can use this, for the default path at least
+  but 1024 * 0.909 == 930.9, shouldn't we be rounding down? I guess we are
+  rounding up
 
-  try with affine vs. reduce in vips_resize ... on the laptop we see
+  need to fix this if we want to be able to used reduce as a shortcut for
+  similarity
+
+- new vips_reduce:
 
 	affine
 	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
@@ -14,41 +19,13 @@
 	sys	0m0.256s
 
 	reduce
-	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
-	real	0m2.388s
-	user	0m8.544s
-	sys	0m0.244s
-
-  argh
-
-  reducev could be faster with the interpolator inlined ... we could pick a
-  set of masks and just run them along a set of input lines to make an output
-  line
-
-  reduceh ... not so clear, need to pick new masks every output pixel, might
-  not make much difference
-
-  with in-line reducev
-
-	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
-	real	0m1.897s
-	user	0m6.296s
-	sys	0m0.304s
-
-  with in-line reduceh as well
-
-	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
-	real	0m1.838s
-	user	0m6.132s
-	sys	0m0.264s
-
-  more small tweaks
-
 	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
 	real	0m1.818s
 	user	0m5.956s
 	sys	0m0.296s
 
+  add tests for vips_reduce(), update c++ binding, check docs and "see also"
+  lines
 
 
 - get some brightly coloured spots with nohalo / vsqbs on wobble.ws ... very

test/test_resample.py

@@ -100,6 +100,19 @@ class TestResample(unittest.TestCase):
  
             self.assertEqual((x - im).abs().max(), 0)
 
+    def test_reduce(self):
+        im = Vips.Image.new_from_file("images/IMG_4618.jpg")
+        bicubic = Vips.Interpolate.new("bicubic")
+        
+        for fac in [1, 1.1, 1.5, 1.999]:
+            print("fac =", fac)
+            r = im.reduce(fac, fac)
+            a = im.affine([1.0 / fac, 0, 0, 1.0 / fac], interpolate = bicubic)
+            r.write_to_file("r.v")
+            a.write_to_file("a.v")
+            d = (r - a).abs().max()
+            self.assertLess(d, 0.1)
+
     def test_resize(self):
         im = Vips.Image.new_from_file("images/IMG_4618.jpg")
         im2 = im.resize(0.25)