// Created on: 2012-07-10 // Created by: VRO // Copyright (c) 2012-2014 OPEN CASCADE SAS // // This file is part of Open CASCADE Technology software library. // // This library is free software; you can redistribute it and/or modify it under // the terms of the GNU Lesser General Public License version 2.1 as published // by the Free Software Foundation, with special exception defined in the file // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT // distribution for complete text of the license and disclaimer of any warranty. // // Alternatively, this file may be used under the terms of Open CASCADE // commercial license or contractual agreement. #ifndef Image_Diff_HeaderFile #define Image_Diff_HeaderFile #include #include #include #include #include //! This class compares two images pixel-by-pixel. //! It uses the following methods to ignore the difference between images: //! - Black/White comparison. It makes the images 2-colored before the comparison. //! - Equality with tolerance. Colors of two pixels are considered the same if the //! difference of their color is less than a tolerance. //! - Border filter. The algorithm ignores alone independent pixels, //! which are different on both images, ignores the "border effect" - //! the difference caused by triangles located at angle about 0 or 90 degrees to the user. //! //! Border filter ignores a difference in implementation of //! anti-aliasing and other effects on boundary of a shape. //! The triangles of a boundary zone are usually located so that their normals point aside the user //! (about 90 degree between the normal and the direction to the user's eye). //! Deflection of the light for such a triangle depends on implementation of the video driver. //! In order to skip this difference the following algorithm is used: //! a) "Different" pixels are groupped and checked on "one-pixel width line". //! indeed, the pixels may represent not a line, but any curve. //! But the width of this curve should be not more than a pixel. //! This group of pixels become a candidate to be ignored because of boundary effect. //! b) The group of pixels is checked on belonging to a "shape". //! Neighbour pixels are checked from the reference image. //! This test confirms a fact that the group of pixels belongs to a shape and //! represent a boundary of the shape. //! In this case the whole group of pixels is ignored (considered as same). //! Otherwise, the group of pixels may represent a geometrical curve in the viewer 3D //! and should be considered as "different". //! //! References: //! 1. http://pdiff.sourceforge.net/ypg01.pdf //! 2. http://pdiff.sourceforge.net/metric.html //! 3. http://www.cs.ucf.edu/~sumant/publications/sig99.pdf //! 4. http://www.worldscientific.com/worldscibooks/10.1142/2641#t=toc (there is a list of articles and books in PDF format) class Image_Diff : public Standard_Transient { public: //! An empty constructor. Init() should be called for initialization. Standard_EXPORT Image_Diff(); //! Destructor. Standard_EXPORT virtual ~Image_Diff(); //! Initialize algorithm by two images. //! @return false if images has different or unsupported pixel format. Standard_EXPORT Standard_Boolean Init (const Handle(Image_PixMap)& theImageRef, const Handle(Image_PixMap)& theImageNew, const Standard_Boolean theToBlackWhite = Standard_False); //! Initialize algorithm by two images (will be loaded from files). //! @return false if images couldn't be opened or their format is unsupported. Standard_EXPORT Standard_Boolean Init (const TCollection_AsciiString& theImgPathRef, const TCollection_AsciiString& theImgPathNew, const Standard_Boolean theToBlackWhite = Standard_False); //! Color tolerance for equality check. Should be within range 0..1: //! Corresponds to a difference between white and black colors (maximum difference). //! By default, the tolerance is equal to 0 thus equality check will return false for any different colors. void SetColorTolerance (const Standard_Real theTolerance) { myColorTolerance = theTolerance; } //! Color tolerance for equality check. Standard_Real ColorTolerance() const { return myColorTolerance; } //! Sets taking into account (ignoring) a "border effect" on comparison of images. //! The border effect is caused by a border of shaded shapes in the viewer 3d. //! Triangles of this area are located at about 0 or 90 degrees to the user. //! Therefore, they deflect light differently according to implementation of a video card driver. //! This flag allows to detect such a "border" area and skip it from comparison of images. //! Filter turned OFF by default. void SetBorderFilterOn (const Standard_Boolean theToIgnore) { myIsBorderFilterOn = theToIgnore; } //! Returns a flag of taking into account (ignoring) a border effect in comparison of images. Standard_Boolean IsBorderFilterOn() const { return myIsBorderFilterOn; } //! Compares two images. It returns a number of different pixels (or groups of pixels). //! It returns -1 if algorithm not initialized before. Standard_EXPORT Standard_Integer Compare(); //! Saves a difference between two images as white pixels on black background. Standard_EXPORT Standard_Boolean SaveDiffImage (Image_PixMap& theDiffImage) const; //! Saves a difference between two images as white pixels on black background. Standard_EXPORT Standard_Boolean SaveDiffImage (const TCollection_AsciiString& theDiffPath) const; protected: //! Perform border filter algorithm. Standard_EXPORT Standard_Integer ignoreBorderEffect(); //! Release dynamically allocated memory. Standard_EXPORT void releaseGroupsOfDiffPixels(); protected: //! Map two pixel coordinates to 32-bit integer static Standard_Integer PackXY (uint16_t theX, uint16_t theY) { return Standard_Integer((unsigned int)theY | ((unsigned int)theX << 16)); } //! Get pixel X coordinate from 32-bit packed integer static uint16_t UnpackX (Standard_Integer theXY) { return (uint16_t)(((unsigned int)theXY & 0xffff0000) >> 16); } //! Get pixel Y coordinate from 32-bit packed integer static uint16_t UnpackY (Standard_Integer theXY) { return (uint16_t)((unsigned int)theXY & 0xffff); } protected: Handle(Image_PixMap) myImageRef; //!< reference image to compare (from) Handle(Image_PixMap) myImageNew; //!< new image to compare (to) Standard_Real myColorTolerance; //!< tolerance for equality check (0..1, 0 - any not equal, 1 - opposite colors) Standard_Boolean myIsBorderFilterOn; //!< perform algorithm with border effect filter //! coordinates of different pixels, packed in one int using 16-bit integers to save memory NCollection_Vector myDiffPixels; TColStd_PackedMapOfInteger myLinearGroups; NCollection_List myGroupsOfDiffPixels; public: DEFINE_STANDARD_RTTIEXT(Image_Diff,Standard_Transient) // Type definition }; DEFINE_STANDARD_HANDLE(Image_Diff, Standard_Transient) #endif // _Image_Diff_H__