Improve documentation and simplify test code

2 files changed, 14 insertions, 2 deletions

diff --git a/integralimg.go b/integralimg.go
index 0ad734b..c088be4 100644
--- a/integralimg.go
+++ b/integralimg.go
@@ -6,6 +6,18 @@
 // summed area tables. These are structures which precompute the
 // sum of pixels to the left and above each pixel, which can make
 // several common image processing operations much faster.
+//
+// integralimg.Image and integralimg.SqImage fully implement the
+// image.Image and image/draw.Draw interfaces, and hence can be
+// used like so:
+//
+//     img, _, err := image.Decode(f)
+//     integral := integralimg.NewImage(b)
+//     draw.Draw(integral, b, img, b.Min, draw.Src)
+//
+// This package also defines a Window, which is a rectangular
+// section of an integral image. This has several methods to do
+// useful calculations on the part of the image represented.
 package integralimg
 
 import (
diff --git a/integralimg_test.go b/integralimg_test.go
index 8b882db..627249f 100644
--- a/integralimg_test.go
+++ b/integralimg_test.go
@@ -24,7 +24,7 @@ func TestFromPNG(t *testing.T) {
 	}
 	b := img.Bounds()
 
-	integral := NewImage(image.Rect(0, 0, b.Dx(), b.Dy()))
+	integral := NewImage(b)
 	draw.Draw(integral, b, img, b.Min, draw.Src)
 
 	if !imgsequal(img, integral) {
@@ -44,7 +44,7 @@ func TestSqFromPNG(t *testing.T) {
 	}
 	b := img.Bounds()
 
-	integral := NewSqImage(image.Rect(0, 0, b.Dx(), b.Dy()))
+	integral := NewSqImage(b)
 	draw.Draw(integral, b, img, b.Min, draw.Src)
 
 	if !imgsequal(img, integral) {