diff --git a/README.md b/README.md
index dc9fb8d3..b70d362c 100755
--- a/README.md
+++ b/README.md
@@ -31,8 +31,9 @@ This module is powered by the blazingly fast [libvips](https://github.com/jcupit
 
 ### Prerequisites
 
-* Node.js v0.10+
+* Node.js v0.10+ or io.js
 * [libvips](https://github.com/jcupitt/libvips) v7.40.0+ (7.42.0+ recommended)
+* C++11 compatible compiler such as gcc 4.6+ or clang 3.0+
 
 To install the most suitable version of libvips on the following Operating Systems:
 
@@ -328,13 +329,23 @@ Possible values are `north`, `east`, `south`, `west`, `center` and `centre`. The
 
 #### max()
 
-Preserving aspect ratio, resize the image to the maximum `width` or `height` specified.
+Preserving aspect ratio,
+resize the image to be as large as possible
+while ensuring its dimensions are less than or equal to
+the `width` and `height` specified.
+
+This is equivalent to using the `contain` value of the CSS `background-size` property.
 
 Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
 
 #### min()
 
-Preserving aspect ratio, resize the image to the minimum `width` or `height` specified.
+Preserving aspect ratio,
+resize the image to be as small as possible
+while ensuring its dimensions are greater than or equal to
+the `width` and `height` specified.
+
+This is equivalent to using the `cover` value of the CSS `background-size` property.
 
 Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
 
diff --git a/src/resize.cc b/src/resize.cc
index d7410a63..57dbc591 100755
--- a/src/resize.cc
+++ b/src/resize.cc
@@ -248,7 +248,7 @@ class ResizeWorker : public NanAsyncWorker {
     int interpolatorWindowSize = InterpolatorWindowSize(baton->interpolator.c_str());
 
     // Scaling calculations
-    double factor;
+    double factor = 1.0;
     if (baton->width > 0 && baton->height > 0) {
       // Fixed width and height
       double xfactor = static_cast<double>(inputWidth) / static_cast<double>(baton->width);
@@ -287,7 +287,6 @@ class ResizeWorker : public NanAsyncWorker {
       baton->width = floor(static_cast<double>(inputWidth) / factor);
     } else {
       // Identity transform
-      factor = 1;
       baton->width = inputWidth;
       baton->height = inputHeight;
     }