1mjb – January 29, 2013Oregon State UniversityComputer GraphicsUsing Fragment Shaders to Manipulate ImageryMike [email protected] State Universitymjb – January 29, 2013Oregon State UniversityComputer GraphicsImage BasicsResSResTTreat the image as a texture. If you need it, the resolution of this texture can be found by saying:To get from the current texel to a neighboring texel, add±(1./ResS , 1./ResT)to the current (S,T) ivec2 ires = textureSize( ImageUnit, 0 );float ResS = float( ires.s );float ResT = float( ires.t );2mjb – January 29, 2013Oregon State UniversityComputer GraphicsImage Negative( R, G, B ) ( 1.-R, 1.-G, 1.-B )mjb – January 29, 2013Oregon State UniversityComputer GraphicsImage Distortionuniform float uS0, uT0;uniform float uPower;uniform sampler2D uTexUnit;in vec2 vST;out vec4 fFragColor;voidmain( ){vec2 delta = vST - vec2(uS0,uT0);st = vec2(uS0,uT0) + sign(delta) * pow( abs(delta), uPower );vec3 rgb = texture2D( uTexUnit, vST ).rgb;fFragColor = vec4( rgb, 1. );}3mjb – January 29, 2013Oregon State UniversityComputer Graphics0 1(1 )Q t Q tQ= − +Image Un-masking:Interpolation can still happen when t < 0. or t > 1.t = -1.t = 0.t = 2.t = 1.mjb – January 29, 2013Oregon State UniversityComputer GraphicsImage Un-Masking:Abusing the Linear Blending Equation for a Good PurposetWhat Idon’t wantMore of what Ido wantWhat I have to start with0.0 1.0 2.0Iout= (1 - t)*Idontwant+ t*Iin}}Blend of what I have and what I don’t wantBlend of what I have and less of what I don’t want0 1(1 )Q t Q tQ= − +4mjb – January 29, 2013Oregon State UniversityComputer GraphicsBrightnessIdontwant= vec3( 0., 0., 0. );T = 0. T = 1. T = 2.mjb – January 29, 2013Oregon State UniversityComputer GraphicsContrastIdontwant= vec3( 0.5, 0.5, 0.5 );T = 0. T = 1. T = 2.5mjb – January 29, 2013Oregon State UniversityComputer GraphicsHDTV Luminance StandardLuminance = 0.2125*Red + 0.7154*Green + 0.0721*Bluemjb – January 29, 2013Oregon State UniversityComputer GraphicsIdontwant= vec3( luminance, luminance, luminance );SaturationT = 0. T = 1. T = 3.6mjb – January 29, 2013Oregon State UniversityComputer GraphicsDifferenceIdontwant= IbeforeIin= IafterT = 0. T = 2.T = 1.mjb – January 29, 2013Oregon State UniversityComputer GraphicsChromaKeyReplace fragment if:R < TG < TB > 1.-TT = 0. T = 0.5 T = 1.7mjb – January 29, 2013Oregon State UniversityComputer GraphicsBlur Convolution:Blur=121242121.16.1Bmjb – January 29, 2013Oregon State UniversityComputer GraphicsBlur Convolution:Sharpening=121242121.16.1BIdontwant= Iblur8mjb – January 29, 2013Oregon State UniversityComputer GraphicsSharpeningvec2 stp0 = vec2(1./ResS, 0. );vec2 st0p = vec2(0. , 1./ResT);vec2 stpp = vec2(1./ResS, 1./ResT);vec2 stpm = vec2(1./ResS, -1./ResT);vec3 i00 = texture2D( uImageUnit, vST ).rgb;vec3 im1m1 = texture2D( uImageUnit, vST-stpp ).rgb;vec3 ip1p1 = texture2D( uImageUnit, vST+stpp ).rgb;vec3 im1p1 = texture2D( uImageUnit, vST-stpm ).rgb;vec3 ip1m1 = texture2D( uImageUnit, vST+stpm ).rgb;vec3 im10 = texture2D( uImageUnit, vST-stp0 ).rgb;vec3 ip10 = texture2D( uImageUnit, vST+stp0 ).rgb;vec3 i0m1 = texture2D( uImageUnit, vST-st0p ).rgb;vec3 i0p1 = texture2D( uImageUnit, vST+st0p ).rgb;vec3 target = vec3(0.,0.,0.);target += 1.*(im1m1+ip1m1+ip1p1+im1p1);target += 2.*(im10+ip10+i0m1+i0p1);target += 4.*(i00);target /= 16.;fFragColor = vec4( mix( target, irgb, T ), 1. );mjb – January 29, 2013Oregon State UniversityComputer GraphicsSharpeningT = 0.T = 1.T = 2.9mjb – January 29, 2013Oregon State UniversityComputer GraphicsEmbossingvec2 stp0 = vec2( 1./ResS, 0. );vec2 stpp = vec2( 1./ResS, 1./ResT);vec3 c00 = texture2D( uImageUnit, vST ).rgb;vec3 cp1p1 = texture2D( uImageUnit, vST + stpp ).rgb;vec3 diffs = c00 - cp1p1;float max = diffs.r;if( abs(diffs.g) > abs(max) )max = diffs.g;if( abs(diffs.b) > abs(max) )max = diffs.b;float gray = clamp( max + .5, 0., 1. );vec4 grayVersion = vec4( gray, gray, gray, 1. );vec4 colorVersion = vec4( gray*c00, 1. );fFragColor = mix( grayVersion, colorVersion, T );mjb – January 29, 2013Oregon State UniversityComputer GraphicsHorizontal and Vertical Sobel Convolutions:Edge Detection−−−=121000121H−−−=101202101VVHS22+=Θ = atan2( V, H )10mjb – January 29, 2013Oregon State UniversityComputer GraphicsEdge Detectionconst vec3 LUMCOEFFS = vec3( 0.2125,0.7154,0.0721 );. . .vec2 stp0 = vec2(1./ResS, 0. );vec2 st0p = vec2(0. , 1./ResT);vec2 stpp = vec2(1./ResS, 1./ResT);vec2 stpm = vec2(1./ResS, -1./ResT);float i00 = dot( texture2D( uImageUnit, vST ).rgb , LUMCOEFFS );float im1m1 = dot( texture2D( uImageUnit, vST-stpp ).rgb, LUMCOEFFS );float ip1p1 = dot( texture2D( uImageUnit, vST+stpp ).rgb, LUMCOEFFS );float im1p1 = dot( texture2D( uImageUnit, vST-stpm ).rgb, LUMCOEFFS );float ip1m1 = dot( texture2D( uImageUnit, vST+stpm ).rgb, LUMCOEFFS );float im10 = dot( texture2D( uImageUnit, vST-stp0 ).rgb, LUMCOEFFS );float ip10 = dot( texture2D( uImageUnit, vST+stp0 ).rgb, LUMCOEFFS );float i0m1 = dot( texture2D( uImageUnit, vST-st0p ).rgb, LUMCOEFFS );float i0p1 = dot( texture2D( uImageUnit, vST+st0p ).rgb, LUMCOEFFS) );float h = -1.*im1p1 - 2.*i0p1 - 1.*ip1p1 + 1.*im1m1 + 2.*i0m1 + 1.*ip1m1;float v = -1.*im1m1 - 2.*im10 - 1.*im1p1 + 1.*ip1m1 + 2.*ip10 + 1.*ip1p1;float mag = sqrt( h*h + v*v );vec3 target = vec3( mag,mag,mag );color = vec4( mix( irgb, target, T ), 1. );mjb – January 29, 2013Oregon State UniversityComputer GraphicsEdge DetectionT = 0. T = 0.5 T = 1.11mjb – January 29, 2013Oregon State UniversityComputer Graphicsfloat mag = sqrt( h*h + v*v );if( mag > uMagTol ){fFragColor= vec4( 0., 0., 0., 1. );}else{rgb.rgb *= uQuantize;rgb.rgb += vec3( .5, .5, .5 );ivec3 irgb = ivec3( rgb.rgb );rgb.rgb = vec3( irgb ) / uQuantize;fFragColor = vec4( rgb, 1. );}Toon Renderingmjb – January 29, 2013Oregon State UniversityComputer GraphicsToon RenderingOriginal ImageColors QuantizedOutlines Added12mjb – January 29, 2013Oregon State UniversityComputer GraphicsUse the GPU to enhance scientific, engineering, and architectural illustrationToon Rendering for Non-Photorealistic Effectsmjb – January 29, 2013Oregon State UniversityComputer GraphicsToon Rendering for Non-Photorealistic EffectsUse the GPU to enhance scientific, engineering, and architectural