网上搜罗了一堆的美颜滤镜效果，可惜尽不如人意。最后偶然看到ios上提供了一个用OC写的美颜滤镜。

先上效果图：

网上搜涨痘痘的图片，搜到刘涛了，罪过罪过~

原图：

美颜后：

可见有四个可滑动的bar，从上到下分别是，磨皮度，磨皮值，美白，红润。

美颜原理

磨皮：本质就是让像素点模糊，可以使用高斯模糊，但是可能导致边缘会不清晰，用双边滤波(Bilateral Filter) ，有针对性的模糊像素点，能保证边缘不被模糊。
美白：本质就是提高亮度。
红润：本质就是改变色调。

下面是滤镜源码：

import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.opengl.GLES20; import android.opengl.GLSurfaceView; import android.opengl.Matrix; import android.view.WindowManager; import com.ws.gl.opengltexture.programs.TextureShaderProgram; import com.ws.gl.opengltexture.util.GLBitmapUtils; import com.ws.gl.opengltexture.util.MatrixHelper; import com.ws.gl.opengltexture.util.TextureHelper; import com.ws.ijk.openglpicture.R; import java.nio.FloatBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; public class BeautyRenderer implements GLSurfaceView.Renderer{ public static final String VERTEX_SHADER = "" + "attribute vec4 vPosition;\n" + "uniform mat4 vMatrix;\n"+ "attribute vec2 vCoordinate;\n" + " \n" + "varying vec2 textureCoordinate;\n" + " \n" + "void main()\n" + "{\n" + "    gl_Position =vMatrix* vPosition;\n" + "    textureCoordinate = vCoordinate;\n" + "}"; public static final String BILATERAL_FRAGMENT_SHADER = "" + "precision highp float;\n"+ "   varying highp vec2 textureCoordinate;\n" + "\n" + "    uniform sampler2D vTexture;\n" + "\n" + "    uniform highp vec2 singleStepOffset;\n" + "    uniform highp vec4 params;\n" + "    uniform highp float brightness;\n" + "    uniform float texelWidthOffset;\n"+ "    uniform float texelHeightOffset;\n"+ "\n" + "    const highp vec3 W = vec3(0.299, 0.587, 0.114);\n" + "    const highp mat3 saturateMatrix = mat3(\n" + "        1.1102, -0.0598, -0.061,\n" + "        -0.0774, 1.0826, -0.1186,\n" + "        -0.0228, -0.0228, 1.1772);\n" + "    highp vec2 blurCoordinates[24];\n" + "\n" + "    highp float hardLight(highp float color) {\n" + "    if (color <= 0.5)\n" + "        color = color * color * 2.0;\n" + "    else\n" + "        color = 1.0 - ((1.0 - color)*(1.0 - color) * 2.0);\n" + "    return color;\n" + "}\n" + "\n" + "    void main(){\n" + "    highp vec3 centralColor = texture2D(vTexture, textureCoordinate).rgb;\n" + "    vec2 singleStepOffset=vec2(texelWidthOffset,texelHeightOffset);\n"+ "    blurCoordinates[0] = textureCoordinate.xy + singleStepOffset * vec2(0.0, -10.0);\n" + "    blurCoordinates[1] = textureCoordinate.xy + singleStepOffset * vec2(0.0, 10.0);\n" + "    blurCoordinates[2] = textureCoordinate.xy + singleStepOffset * vec2(-10.0, 0.0);\n" + "    blurCoordinates[3] = textureCoordinate.xy + singleStepOffset * vec2(10.0, 0.0);\n" + "    blurCoordinates[4] = textureCoordinate.xy + singleStepOffset * vec2(5.0, -8.0);\n" + "    blurCoordinates[5] = textureCoordinate.xy + singleStepOffset * vec2(5.0, 8.0);\n" + "    blurCoordinates[6] = textureCoordinate.xy + singleStepOffset * vec2(-5.0, 8.0);\n" + "    blurCoordinates[7] = textureCoordinate.xy + singleStepOffset * vec2(-5.0, -8.0);\n" + "    blurCoordinates[8] = textureCoordinate.xy + singleStepOffset * vec2(8.0, -5.0);\n" + "    blurCoordinates[9] = textureCoordinate.xy + singleStepOffset * vec2(8.0, 5.0);\n" + "    blurCoordinates[10] = textureCoordinate.xy + singleStepOffset * vec2(-8.0, 5.0);\n" + "    blurCoordinates[11] = textureCoordinate.xy + singleStepOffset * vec2(-8.0, -5.0);\n" + "    blurCoordinates[12] = textureCoordinate.xy + singleStepOffset * vec2(0.0, -6.0);\n" + "    blurCoordinates[13] = textureCoordinate.xy + singleStepOffset * vec2(0.0, 6.0);\n" + "    blurCoordinates[14] = textureCoordinate.xy + singleStepOffset * vec2(6.0, 0.0);\n" + "    blurCoordinates[15] = textureCoordinate.xy + singleStepOffset * vec2(-6.0, 0.0);\n" + "    blurCoordinates[16] = textureCoordinate.xy + singleStepOffset * vec2(-4.0, -4.0);\n" + "    blurCoordinates[17] = textureCoordinate.xy + singleStepOffset * vec2(-4.0, 4.0);\n" + "    blurCoordinates[18] = textureCoordinate.xy + singleStepOffset * vec2(4.0, -4.0);\n" + "    blurCoordinates[19] = textureCoordinate.xy + singleStepOffset * vec2(4.0, 4.0);\n" + "    blurCoordinates[20] = textureCoordinate.xy + singleStepOffset * vec2(-2.0, -2.0);\n" + "    blurCoordinates[21] = textureCoordinate.xy + singleStepOffset * vec2(-2.0, 2.0);\n" + "    blurCoordinates[22] = textureCoordinate.xy + singleStepOffset * vec2(2.0, -2.0);\n" + "    blurCoordinates[23] = textureCoordinate.xy + singleStepOffset * vec2(2.0, 2.0);\n" + "\n" + "    highp float sampleColor = centralColor.g * 22.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[0]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[1]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[2]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[3]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[4]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[5]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[6]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[7]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[8]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[9]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[10]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[11]).g;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[12]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[13]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[14]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[15]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[16]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[17]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[18]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[19]).g * 2.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[20]).g * 3.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[21]).g * 3.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[22]).g * 3.0;\n" + "    sampleColor += texture2D(vTexture, blurCoordinates[23]).g * 3.0;\n" + "\n" + "    sampleColor = sampleColor / 62.0;\n" + "\n" + "    highp float highPass = centralColor.g - sampleColor + 0.5;\n" + "\n" + "    for (int i = 0; i < 5; i++) {\n" + "        highPass = hardLight(highPass);\n" + "    }\n" + "    highp float lumance = dot(centralColor, W);\n" + "\n" + "    highp float alpha = pow(lumance, params.r);\n" + "\n" + "    highp vec3 smoothColor = centralColor + (centralColor-vec3(highPass))*alpha*0.1;\n" + "\n" + "    smoothColor.r = clamp(pow(smoothColor.r, params.g), 0.0, 1.0);\n" + "    smoothColor.g = clamp(pow(smoothColor.g, params.g), 0.0, 1.0);\n" + "    smoothColor.b = clamp(pow(smoothColor.b, params.g), 0.0, 1.0);\n" + "\n" + "    highp vec3 lvse = vec3(1.0)-(vec3(1.0)-smoothColor)*(vec3(1.0)-centralColor);\n" + "    highp vec3 bianliang = max(smoothColor, centralColor);\n" + "    highp vec3 rouguang = 2.0*centralColor*smoothColor + centralColor*centralColor - 2.0*centralColor*centralColor*smoothColor;\n" + "\n" + "    gl_FragColor = vec4(mix(centralColor, lvse, alpha), 1.0);\n" + "    gl_FragColor.rgb = mix(gl_FragColor.rgb, bianliang, alpha);\n" + "    gl_FragColor.rgb = mix(gl_FragColor.rgb, rouguang, params.b);\n" + "\n" + "    highp vec3 satcolor = gl_FragColor.rgb * saturateMatrix;\n" + "    gl_FragColor.rgb = mix(gl_FragColor.rgb, satcolor, params.a);\n" + "    gl_FragColor.rgb = vec3(gl_FragColor.rgb + vec3(brightness));\n" + "}"; private Context context; private TextureShaderProgram textureProgram; private int texture; private final float[] projectionMatrix = new float[16]; private final float[] modelMatrix = new float[16]; private Picture picture; public int mWidth,mHeight; private float toneLevel; private float beautyLevel; private float brightLevel; private float texelWidthOffset; private float texelHeightOffset; private int paramsLocation; private int brightnessLocation; private int singleStepOffsetLocation; private int texelWidthLocation; private int texelHeightLocation; private boolean isTakePicture; public BeautyRenderer(Context context) { this.context = context;
        texelWidthOffset=texelHeightOffset=2;
        toneLevel = -0.5f; 
        beautyLevel =1.2f; 
        brightLevel =0.47f; 

        WindowManager wm = ((Activity)context).getWindowManager();
        mWidth = wm.getDefaultDisplay().getWidth();
        mHeight = wm.getDefaultDisplay().getHeight();
    } @Override public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {
        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

        picture = new Picture();
        textureProgram = new TextureShaderProgram(VERTEX_SHADER,BILATERAL_FRAGMENT_SHADER);
        texture = TextureHelper.loadTexture(context, R.mipmap.liu);


        paramsLocation = GLES20.glGetUniformLocation(textureProgram.getProgram(), "params");
        brightnessLocation = GLES20.glGetUniformLocation(textureProgram.getProgram(), "brightness");
        singleStepOffsetLocation = GLES20.glGetUniformLocation(textureProgram.getProgram(), "singleStepOffset");
        texelWidthLocation = GLES20.glGetUniformLocation(textureProgram.getProgram(), "texelWidthOffset");
        texelHeightLocation = GLES20.glGetUniformLocation(textureProgram.getProgram(), "texelHeightOffset");

    } @Override public void onSurfaceChanged(GL10 gl10, int width, int height) {
        GLES20.glViewport(0, 0, width,height);

        MatrixHelper.perspectiveM(projectionMatrix,45,(float)width/(float)height,1f,10f);

        Matrix.setIdentityM(modelMatrix,0);
        Matrix.translateM(modelMatrix,0,0f,0f,-2.5f); //Matrix.rotateM(modelMatrix,0,-60f,1f,0f,0f); final float[] temp = new float[16];
        Matrix.multiplyMM(temp,0,projectionMatrix,0,modelMatrix,0);
        System.arraycopy(temp,0,projectionMatrix,0,temp.length);


        setTexelSize(width, height);
        mWidth = width;
        mHeight = height;

    } @Override public void onDrawFrame(GL10 gl10) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        textureProgram.useProgram();
        textureProgram.setUniforms(projectionMatrix,texture);


        setParams(beautyLevel, toneLevel);
        setBrightLevel(brightLevel);
        setTexelOffset(texelWidthOffset);


        picture.bindData(textureProgram);
        picture.draw(); // 获取GLSurfaceView的图片并保存 if (isTakePicture) { /* Bitmap bmp = GLBitmapUtils.createBitmapFromGLSurface(0, 0, mWidth,
                    mHeight, gl10);*/ GLBitmapUtils.saveImage(mWidth,mHeight,context);
            isTakePicture = false;
        }

    } public void setTexelOffset(float texelOffset) {
        texelWidthOffset=texelHeightOffset=texelOffset;
        setFloat(texelWidthLocation, texelOffset/mWidth);
        setFloat(texelHeightLocation, texelOffset/mHeight);
    } public void setToneLevel(float toneLeve) { this.toneLevel = toneLeve;
        setParams(beautyLevel, toneLevel);
    } public void setBeautyLevel(float beautyLeve) { this.beautyLevel = beautyLeve;
        setParams(beautyLevel, toneLevel);
    } public void setBrightLevel(float brightLevel) { this.brightLevel = brightLevel;
        setFloat(brightnessLocation, 0.6f * (-0.5f + brightLevel));
    } public void setParams(float beauty, float tone) { this.beautyLevel=beauty; this.toneLevel = tone; float[] vector = new float[4];
        vector[0] = 1.0f - 0.6f * beauty;
        vector[1] = 1.0f - 0.3f * beauty;
        vector[2] = 0.1f + 0.3f * tone;
        vector[3] = 0.1f + 0.3f * tone;
        setFloatVec4(paramsLocation, vector);
    } private void setTexelSize(final float w, final float h) {
        setFloatVec2(singleStepOffsetLocation, new float[] {2.0f / w, 2.0f / h});
    } protected void setFloat(final int location, final float floatValue) {
       GLES20.glUniform1f(location, floatValue);
   } protected void setFloatVec2(final int location, final float[] arrayValue) {
        GLES20.glUniform2fv(location, 1, FloatBuffer.wrap(arrayValue));
    } protected void setFloatVec3(final int location, final float[] arrayValue) {
        GLES20.glUniform3fv(location, 1, FloatBuffer.wrap(arrayValue));
    } protected void setFloatVec4(final int location, final float[] arrayValue) {
        GLES20.glUniform4fv(location, 1, FloatBuffer.wrap(arrayValue));
    } public void saveImage(){
        isTakePicture =true;
    }
}

使用：

import android.opengl.GLSurfaceView; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.SeekBar; import com.ws.gl.opengltexture.util.GLBitmapUtils; import com.ws.ijk.openglpicture.R; public class BeautyActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener { private GLSurfaceView glSurfaceView; private BeautyRenderer mRenderer; private ImageView mImageView; private Button startBtn,saveBtn; private boolean isStart=true; private SeekBar sb_step,sb_tone,sb_beauty,sb_bright; private static float minstepoffset= -10; private static float maxstepoffset= 10; private static float minToneValue= -5; private static float maxToneValue= 5; private static float minbeautyValue= 0; private static float maxbeautyValue= 2.5f; private static float minbrightValue= 0; private static float maxbrightValue= 1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_beauty);

        glSurfaceView= (GLSurfaceView) findViewById(R.id.glView);
        glSurfaceView.setEGLContextClientVersion(2);
        mRenderer =new BeautyRenderer(this);
        glSurfaceView.setRenderer(mRenderer);
        glSurfaceView.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);

        mImageView= (ImageView) findViewById(R.id.image);
        mImageView.setImageResource(R.mipmap.liu);
        startBtn = (Button) findViewById(R.id.startbtn);
        startBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { if(isStart){
                    mImageView.setVisibility(View.GONE);

                }else {
                    mImageView.setVisibility(View.VISIBLE);
                }
                isStart = !isStart;
            }
        });

        saveBtn  = (Button) findViewById(R.id.picBtn);
        saveBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) {
                mRenderer.saveImage();
                glSurfaceView.requestRender();
            }
        });


        initView();
    } private void initView() {
        sb_step = (SeekBar) findViewById(R.id.sb_step);
        sb_step.setOnSeekBarChangeListener(this);
        sb_tone = (SeekBar) findViewById(R.id.sb_tone);
        sb_tone.setOnSeekBarChangeListener(this);
        sb_beauty = (SeekBar) findViewById(R.id.sb_beauty);
        sb_beauty.setOnSeekBarChangeListener(this);
        sb_bright = (SeekBar) findViewById(R.id.sb_bright);
        sb_bright.setOnSeekBarChangeListener(this);
    } @Override protected void onPause() { super.onPause();
        glSurfaceView.onPause();
    } @Override protected void onResume() { super.onResume();
        glSurfaceView.onResume();
    } @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean b) { switch (seekBar.getId()){ case R.id.sb_step:

                      mRenderer.setTexelOffset(range(progress,minstepoffset,maxstepoffset)); break; case R.id.sb_tone:

                      mRenderer.setToneLevel(range(progress,minToneValue,maxToneValue)); break; case R.id.sb_beauty:
                    mRenderer.setBeautyLevel(range(progress,minbeautyValue,maxbeautyValue)); break; case R.id.sb_bright:

                      mRenderer.setBrightLevel(range(progress,minbrightValue,maxbrightValue)); break;
              }
              glSurfaceView.requestRender();
    } @Override public void onStartTrackingTouch(SeekBar seekBar) {

    } @Override public void onStopTrackingTouch(SeekBar seekBar) {

    } protected float range(final int percentage, final float start, final float end) { return (end - start) * percentage / 100.0f + start;
    }
}