Merge pull request opencv#3 from VladVin/fix/vignette

Fixed the vignette filter

Author: ArtemSkrebkov

modules/photoeffects/doc/vignette.rst

@@ -4,31 +4,25 @@ Vignette
 
 Makes the edges of the photo less bright, creating an oval frame around its central part.
 
-.. cpp:function:: int vignette(cv::InputArray src, cv::OutputArray dst, cv::Size rect)
+.. ocv:function:: void vignette(cv::InputArray src, cv::OutputArray dst, cv::Size rect)
 
-   :param src: Source 8-bit three-channel image.
+   :param src: Source 3-channel image.
    :param dst: Destination image of the same size and the same type as **src**.
-   :param rect: Size of rectangle describes an ellipse, whose center is at the center image.
-   :return: Error code.
+   :param rect: Size of rectangle describes an ellipse, whose center is at the center of an image.
 
 The algorithm.
 
-#. Create a new 3-channel image, which is interpreted as BGR image.
+ For every pixel of the **src** image calculate :math:`dist` and :math:`coefficient`, where
+  :math:`dist` is an amount, which describes a distance from the current pixel to border of the ellipse;
+  :math:`coefficient` is a number which cuts a part of the channel's intensity of the **src** image (value is in the range :math:`[0, 1]`). New value stores to the **dst** image.
 
-#. For every channel calculate :math:`dist`, :math:`radius\_ellipse` and :math:`coefficient`, where
-   :math:`dist` is a distance between the current pixel and the center of image;
-   :math:`radius\_ellipse` is a radius of ellipse in the this point which belongs the same line as a pixel;
-   :math:`coefficient` is a number which multiplies the intensity channel.
+  The :math:`coefficient` is calculated by the following formula:
 
-   The :math:`coefficient` is calculated by the following formula:
+  .. math::
 
-   .. math::
+   coefficient = 1 - ((dist - 1) / radiusMax),
 
-      coefficient = 1 - ((dist - radius\_ellipse) / (max\_radius - radius\_ellipse)),
-
-    where :math:`max\_radius` is a distance between the pixel (0, img_src.cols) and the center image.
-
-#. Convert image to a BGR format.
+  where :math:`radiusMax` is a maximum distance from border of the ellipse to the farthest pixel (a corner of the image).
 
 Example.
 

modules/photoeffects/include/opencv2/photoeffects.hpp

@@ -24,7 +24,7 @@ CV_EXPORTS_W  void boostColor(cv::InputArray src, cv::OutputArray dst, float int
 
 CV_EXPORTS_W  int antique(cv::InputArray src, cv::OutputArray dst, cv::InputArray texture, float alpha);
 
-CV_EXPORTS_W  int vignette(cv::InputArray src, cv::OutputArray dst, cv::Size rect);
+CV_EXPORTS_W  void vignette(cv::InputArray src, cv::OutputArray dst, cv::Size rect);
 
 CV_EXPORTS_W  int warmify(cv::InputArray src, cv::OutputArray dst, uchar delta = 30);
 

modules/photoeffects/src/vignette.cpp

@@ -13,7 +13,7 @@ class VignetteInvoker: public cv::ParallelLoopBody
         centerCol = imgSrc.cols / 2.0f;
         aSquare = rect.height * rect.height / 4.0f;
         bSquare = rect.width * rect.width / 4.0f;
-        radiusMax = centerRow * centerRow / aSquare + centerCol * centerCol / bSquare - 1.0f;
+        distMax = centerRow * centerRow / aSquare + centerCol * centerCol / bSquare - 1.0f;
     }
 
     void operator()(const Range& rows) const
@@ -32,7 +32,7 @@ class VignetteInvoker: public cv::ParallelLoopBody
                 float coefficient = 1.0f;
                 if (dist > 1.0f)
                 {
-                    coefficient = 1.0f - (dist - 1.0f) / radiusMax;
+                    coefficient = 1.0f - (dist - 1.0f) / distMax;
                 }
                 dstRow[3 * j] *= coefficient;
                 dstRow[3 * j + 1] *= coefficient;
@@ -44,12 +44,12 @@ class VignetteInvoker: public cv::ParallelLoopBody
 private:
     const Mat& imgSrc;
     Mat& imgDst;
-    float centerRow, centerCol, aSquare, bSquare, radiusMax;
+    float centerRow, centerCol, aSquare, bSquare, distMax;
 
     VignetteInvoker& operator=(const VignetteInvoker&);
 };
 
-int vignette(InputArray src, OutputArray dst, Size rect)
+void vignette(InputArray src, OutputArray dst, Size rect)
 {
     CV_Assert(src.type() == CV_8UC3 && rect.height != 0 && rect.width != 0);
 
@@ -60,8 +60,6 @@ int vignette(InputArray src, OutputArray dst, Size rect)
     Mat imgDst = dst.getMat();
 
     parallel_for_(Range(0, imgSrc.rows), VignetteInvoker(imgSrc, imgDst, rect));
-
-    return 0;
 }
 
-}}
+}}

modules/photoeffects/test/vignette_test.cpp

@@ -5,26 +5,26 @@ using namespace cv::photoeffects;
 
 using namespace std;
 
-TEST(photoeffects_vignette, invalid_arguments)
+TEST(photoeffects_vignette, incorrect_image)
 {
     Mat image(100, 100, CV_8UC1);
     Mat dst;
     Size rectangle;
-    rectangle.height = 0;
-    rectangle.width = 0;
+    rectangle.height = image.rows / 1.5f;
+    rectangle.width = image.cols / 2.0f;
 
     EXPECT_ERROR(CV_StsAssert, vignette(image, dst, rectangle));
 }
 
-TEST(photoeffects_vignette, test)
+TEST(photoeffects_vignette, incorrect_ellipse_size)
 {
     Mat image(100, 100, CV_8UC3);
     Mat dst;
     Size rectangle;
-    rectangle.height = image.rows / 1.5f;
-    rectangle.width = image.cols / 2.0f;
+    rectangle.height = 0.0f;
+    rectangle.width = 0.0f;
 
-    EXPECT_EQ(0, vignette(image, dst, rectangle));
+    EXPECT_ERROR(CV_StsAssert, vignette(image, dst, rectangle));
 }
 
 TEST(photoeffects_vignette, regression)
@@ -45,11 +45,11 @@ TEST(photoeffects_vignette, regression)
         FAIL() << "Can't read " + expectedOutput + " image";
     }
 
-    Size rect;
-    rect.height = image.rows / 1.5f;
-    rect.width = image.cols / 2.0f;
+    Size rectangle;
+    rectangle.height = image.rows / 1.5f;
+    rectangle.width = image.cols / 2.0f;
 
-    EXPECT_EQ(0, vignette(image, dst, rect));
+    vignette(image, dst, rectangle);
 
     Mat diff = abs(rightDst - dst);
     Mat mask = diff.reshape(1) > 1;