Best way to filter for a bloom effect

Jake S. Del Mastro · 2012-10-15T18:09:26

So I have had a bloom effect implemented for some time but I just haven't been able to make it look right. I start my effect by filtering out the really bright parts then I do a two pass Gaussian blur and blend the blurred bright stuff with the original image. I have come to the conclusion that to make it look right I need to tweak how I decide what is bright so far I have two ways neither of which work well. My code is written in GLSL but this really applies to HLSL and cg as well. Anyway the first way goes like this: if(sample.r > level) { sample.r = 1.0; } else { sample.r = 0.0; } if(sample.g > level) { sample.g = 1.0; } else { sample.g = 0.0; } if(sample.b > level) { sample.b = 1.0; } else { sample.b = 0.0; } The problem with this method is that It will always glow either red, green or blue. For example a bright purple would glow red. Method 2: if((0.2126*sample.r) + (0.7152*sample.g) + (0.0722*sample.b) > level) { sample.r = 1.0; sample.g = 1.0; sample.b = 1.0; } else { sample.r = 0.0; sample.g = 0.0; sample.b = 0.0; } This method works by determining the overall brightness (luminance?). But it never seems to glow any color but white. So I developed two methods but neither seem to work right. Does anyone have any methods that they have used successfully? Or any suggestions on how to improve mine?

Graphics and GPU Programming Programming

Started by ic0de October 11, 2012 11:13 PM

10 comments, last by pachesantiago 11 years, 6 months ago

pachesantiago

188

October 15, 2012 06:06 PM

hy. im using this to in my bloom shader. is simple and it works really well





float4 color = tex2D( srcTex, IN.uv );

color = (-color + (pow(tex2D( srcTex, IN.uv ),Power) * Scale) )/Bias;

return color;

here's a screenshot using scale = 1.83, power = 4 and bias = 0.27

PS: this is HLSL, but i think it should be really similar

pachesantiago

188

October 15, 2012 06:09 PM

hy. im using this to in my bloom shader. is simple and it works really well
float4 color = tex2D( srcTex, IN.uv ); color = (-color + (pow(tex2D( srcTex, IN.uv ),Power) * Scale) )/Bias; return color;
here's a screenshot using scale = 1.83, power = 4 and bias = 0.27

PS: this is HLSL, but i think it should be really similar

Sorry, didnt mention that the grayscale is another shader, is not part of the "bright pass"
Using colors:

Best way to filter for a bloom effect

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