From c0000f3aed6723f8ee7905b052aa0f878c2dc3f3 Mon Sep 17 00:00:00 2001
From: Vadim Pisarevsky <no@email>
Date: Tue, 10 Apr 2012 14:28:48 +0000
Subject: [PATCH] added missing contrib & legacy chapters to the reference
manual; fixed (x, y)->(y, x) ordering in Mat.at (ticket #1726)
---
doc/user_guide/ug_mat.rst | 14 +++++++++-----
modules/refman.rst | 2 ++
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/doc/user_guide/ug_mat.rst b/doc/user_guide/ug_mat.rst
index 6e3ecfcf85..4c597d5ad1 100644
--- a/doc/user_guide/ug_mat.rst
+++ b/doc/user_guide/ug_mat.rst
@@ -35,25 +35,29 @@ Accessing pixel intensity values
In order to get pixel intensity value, you have to know the type of an image and the number of channels. Here is an example for a single channel grey scale image (type 8UC1) and pixel coordinates x and y: ::
- Scalar intensity = img.at<uchar>(x, y);
+ Scalar intensity = img.at<uchar>(y, x);
-``intensity.val[0]`` contains a value from 0 to 255. Now let us consider a 3 channel image with ``BGR`` color ordering (the default format returned by ``imread``): ::
+``intensity.val[0]`` contains a value from 0 to 255. Note the ordering of ``x`` and ``y``. Since in OpenCV images are represented by the same structure as matrices, we use the same convention for both cases - the 0-based row index (or y-coordinate) goes first and the 0-based column index (or x-coordinate) follows it. Alternatively, you can use the following notation: ::
- Vec3b intensity = img.at<Vec3b>(x, y);
+ Scalar intensity = img.at<uchar>(Point(x, y));
+
+Now let us consider a 3 channel image with ``BGR`` color ordering (the default format returned by ``imread``): ::
+
+ Vec3b intensity = img.at<Vec3b>(y, x);
uchar blue = intensity.val[0];
uchar green = intensity.val[1];
uchar red = intensity.val[2];
You can use the same method for floating-point images (for example, you can get such an image by running Sobel on a 3 channel image): ::
- Vec3f intensity = img.at<Vec3f>(x, y);
+ Vec3f intensity = img.at<Vec3f>(y, x);
float blue = intensity.val[0];
float green = intensity.val[1];
float red = intensity.val[2];
The same method can be used to change pixel intensities: ::
- img.at<uchar>(x, y) = 128;
+ img.at<uchar>(y, x) = 128;
There are functions in OpenCV, especially from calib3d module, such as ``projectPoints``, that take an array of 2D or 3D points in the form of ``Mat``. Matrix should contain exactly one column, each row corresponds to a point, matrix type should be 32FC2 or 32FC3 correspondingly. Such a matrix can be easily constructed from ``std::vector``: ::
diff --git a/modules/refman.rst b/modules/refman.rst
index e9c08b8f37..dc15ab9d8e 100644
--- a/modules/refman.rst
+++ b/modules/refman.rst
@@ -19,4 +19,6 @@ OpenCV API Reference
photo/doc/photo.rst
stitching/doc/stitching.rst
nonfree/doc/nonfree.rst
+ contrib/doc/contrib.rst
+ legacy/doc/legacy.rst