opengl对图像进行模糊处理

右下角图片为模糊效果图

对图像进行模糊处理也就是平滑处理

图像模糊的用途：用来减少图像上的噪点或失真

同样需要对图像做卷积处理

卷积过程

卷积的数学表达式

本文的图像模糊采用的高斯滤波

具体操作：用一个卷积核扫描图像中的每一个像素,用模板确定的邻域内像素的加权

平均灰度值去替代模板中心像素点的值

opengl 中shader实现

varying vec2 V_Texcoord;uniform sampler2D U_MainTexture;void main(){//高斯滤波核// 1 2 1// 2 4 2// 1 2 1vec4 color=vec4(0.0);int coreSize=3;float texelOffset=1/150.0;float kernel[9];kernel[6]=1;kernel[7]=2;kernel[8]=1;kernel[3]=2;kernel[4]=4;kernel[5]=2;kernel[0]=1;kernel[1]=2;kernel[2]=1;//移动高斯核,对原图做卷积计算int index=0;for(int y=0;y<coreSize;y++){for(int x=0;x<coreSize;x++){//原图像素点vec4 currentColor=texture2D(U_MainTexture,V_Texcoord+vec2((-1+x)*texelOffset,(-1+y)*texelOffset));//卷积计算color+=currentColor*kernel[index++];}}//根据邻域内像素的加权平均灰度值去替代模板中心像素点的值color/=16.0;gl_FragColor=color;}

渲染入口

#include <windows.h>#include "glew.h"#include <stdio.h>#include <math.h>#include "utils.h"#include "GPUProgram.h"#include "ObjModel.h"#include "FBO.h"#include "FullScreenQuad.h"#include "Glm/glm.hpp"#include "Glm/ext.hpp"#pragma comment(lib,"opengl32.lib")#pragma comment(lib,"glew32.lib")LRESULT CALLBACK GLWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam){switch (msg){case WM_CLOSE:PostQuitMessage(0);break;}return DefWindowProc(hwnd,msg,wParam,lParam);}INT WINAPI WinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ LPSTR lpCmdLine, _In_ int nShowCmd){WNDCLASSEX wndClass;wndClass.cbClsExtra = 0;wndClass.cbSize = sizeof(WNDCLASSEX);wndClass.cbWndExtra = 0;wndClass.hbrBackground = NULL;wndClass.hCursor = LoadCursor(NULL,IDC_ARROW);wndClass.hIcon = NULL;wndClass.hIconSm = NULL;wndClass.hInstance = hInstance;wndClass.lpfnWndProc=GLWindowProc;wndClass.lpszClassName = L"OpenGL";wndClass.lpszMenuName = NULL;wndClass.style = CS_VREDRAW | CS_HREDRAW;ATOM atom = RegisterClassEx(&wndClass);RECT rect;rect.left = 0;rect.top = 0;rect.right = 1280;rect.bottom = 720;AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, FALSE);HWND hwnd = CreateWindowEx(NULL, L"OpenGL", L"RenderWindow", WS_OVERLAPPEDWINDOW, 100, 100, rect.right-rect.left, rect.bottom-rect.top, NULL, NULL, hInstance, NULL);HDC dc = GetDC(hwnd);PIXELFORMATDESCRIPTOR pfd;memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));pfd.nVersion = 1;pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_TYPE_RGBA | PFD_DOUBLEBUFFER;pfd.iLayerType = PFD_MAIN_PLANE;pfd.iPixelType = PFD_TYPE_RGBA;pfd.cColorBits = 32;pfd.cDepthBits = 24;pfd.cStencilBits = 8;int pixelFormatID = ChoosePixelFormat(dc, &pfd);SetPixelFormat(dc,pixelFormatID,&pfd);HGLRC rc = wglCreateContext(dc);wglMakeCurrent(dc, rc);GetClientRect(hwnd, &rect);int viewportWidth = rect.right - rect.left, viewportHeight = rect.bottom - rect.top;glewInit();GPUProgram originalProgram;originalProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/fullscreenquad.vs");originalProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/fullscreenquad.fs");originalProgram.Link();originalProgram.DetectAttribute("pos");originalProgram.DetectAttribute("texcoord");originalProgram.DetectUniform("U_MainTexture");GPUProgram erosionProgram;erosionProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/fullscreenquad.vs");erosionProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/Erosion.fs");erosionProgram.Link();erosionProgram.DetectAttribute("pos");erosionProgram.DetectAttribute("texcoord");erosionProgram.DetectUniform("U_MainTexture");GPUProgram dilationProgram;dilationProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/fullscreenquad.vs");dilationProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/Dilation.fs");dilationProgram.Link();dilationProgram.DetectAttribute("pos");dilationProgram.DetectAttribute("texcoord");dilationProgram.DetectUniform("U_MainTexture");GPUProgram gaussianProgram;gaussianProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/fullscreenquad.vs");gaussianProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/Gaussian.fs");gaussianProgram.Link();gaussianProgram.DetectAttribute("pos");gaussianProgram.DetectAttribute("texcoord");gaussianProgram.DetectUniform("U_MainTexture");GPUProgram gpuProgram;gpuProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/x_ray.vs");gpuProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/x_ray.fs");gpuProgram.Link();gpuProgram.DetectAttribute("pos");gpuProgram.DetectAttribute("texcoord");gpuProgram.DetectAttribute("normal");gpuProgram.DetectUniform("M");gpuProgram.DetectUniform("V");gpuProgram.DetectUniform("P");gpuProgram.DetectUniform("NM");gpuProgram.DetectUniform("U_EyePos");//init 3d modelObjModel cube,quad;cube.Init("Debug/res/model/Sphere.obj");//cube.Init("res/model/Quad.obj");float identity[] = {1.0f,0,0,0,0,1.0f,0,0,0,0,1.0f,0,0,0,0,1.0f};float eyePos[] = { -0.5f, 1.5f, -3.0f };glm::mat4 model1 = glm::translate<float>(-2.0f, 0.0f, -6.0f)*glm::rotate(-30.0f, 1.0f, 1.0f, 1.0f);glm::mat4 projectionMatrix = glm::perspective(50.0f, (float)viewportWidth / (float)viewportHeight, 0.1f, 1000.0f);glm::mat4 viewMatrix1 = glm::lookAt(glm::vec3(-0.5f, 1.5f, -3.0f), glm::vec3(-2.0f, 0.0f, -6.0f), glm::vec3(0.0f, 1.0f, 0.0f));glm::mat4 normalMatrix1 = glm::inverseTranspose(model1);FullScreenQuad fsq;fsq.Init();FBO fbo;fbo.AttachColorBuffer("color", GL_COLOR_ATTACHMENT0, GL_RGBA, viewportWidth, viewportHeight);fbo.AttachDepthBuffer("depth", viewportWidth, viewportHeight);fbo.Finish();GLuint mainTexture = CreateTextureFromFile("Debug/res/image/stone.bmp");ShowWindow(hwnd, SW_SHOW);UpdateWindow(hwnd);glClearColor(0.0f, 0.0f, 0.0f, 1.0f);glEnable(GL_DEPTH_TEST);MSG msg;while (true){if (PeekMessage(&msg,NULL,NULL,NULL,PM_REMOVE)){if (msg.message==WM_QUIT){break;}TranslateMessage(&msg);DispatchMessage(&msg);}fbo.Bind();glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);glEnable(GL_BLEND);glBlendFunc(GL_SRC_ALPHA, GL_ONE);glUseProgram(gpuProgram.mProgram);glUniformMatrix4fv(gpuProgram.GetLocation("P"), 1, GL_FALSE, glm::value_ptr(projectionMatrix));glUniform3fv(gpuProgram.GetLocation("U_EyePos"), 1, eyePos);glUniformMatrix4fv(gpuProgram.GetLocation("M"), 1, GL_FALSE, glm::value_ptr(model1));glUniformMatrix4fv(gpuProgram.GetLocation("V"), 1, GL_FALSE, glm::value_ptr(viewMatrix1));glUniformMatrix4fv(gpuProgram.GetLocation("NM"), 1, GL_FALSE, glm::value_ptr(normalMatrix1));cube.Bind(gpuProgram.GetLocation("pos"), gpuProgram.GetLocation("texcoord"), gpuProgram.GetLocation("normal"));cube.Draw();glDisable(GL_BLEND);fbo.Unbind();glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glUseProgram(originalProgram.mProgram);glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, fbo.GetBuffer("color"));glUniform1i(originalProgram.GetLocation("U_MainTexture"), 0);fsq.DrawToLeftTop(originalProgram.GetLocation("pos"), originalProgram.GetLocation("texcoord"));glUseProgram(erosionProgram.mProgram);fsq.DrawToRightTop(erosionProgram.GetLocation("pos"), erosionProgram.GetLocation("texcoord"));glUseProgram(dilationProgram.mProgram);fsq.DrawToLeftBottom(dilationProgram.GetLocation("pos"), dilationProgram.GetLocation("texcoord"));glUseProgram(gaussianProgram.mProgram);glBindTexture(GL_TEXTURE_2D, mainTexture);glUniform1i(gaussianProgram.GetLocation("U_MainTexture"), 0);fsq.DrawToRightBottom(gaussianProgram.GetLocation("pos"), gaussianProgram.GetLocation("texcoord"));glFlush();SwapBuffers(dc);}return 0;}