why this glsl shader isn't working on hdr content?

[geextahslex]

Hi. TLDR: Does someone know why this works on SDR but isn't on HDR? The original shader worked on both and only 3 lines of code have changed... I marked them at the end

more info: This is a vibrance shader that has 2 conditions. The first one is the srgb threshold float Thresh = 200.0/255.0; the 2nd one is the saturation of the pixel delta = smoothstep(0.8, 0.9, colorSat);

By "isn't working" I mean that it visually doesn't change anything. The shader is working in the pipeline but there is no visible effect.

Thank you :)

//!PARAM vibr
//!DESC Saturates/deSaturates
//!TYPE float
//!MINIMUM -1
-0.5

//!HOOK MAIN
//!BIND HOOKED
//!DESC Vibrance

#define CoefLuma vec4(0.2126, 0.7152, 0.0722, 0) //sRGB, HDTV
float Thresh = 200.0/255.0;
float w = 10.0/255.0;

vec4 hook() {
    vec4 c0 = HOOKED_texOff(0);
    float lum = (c0.r + c0.g + c0.b)/3.0;

    float colorSat = max(max(c0.r, c0.g), c0.b) - min(min(c0.r, c0.g), c0.b); 
    vec3 sat = mix(vec3(dot(c0, CoefLuma)), c0.rgb, 1+vibr - colorSat*abs(vibr));
    float delta = smoothstep(Thresh-w, Thresh+w, lum);
1   sat = mix(sat, c0.rgb, delta);
2   delta = smoothstep(0.8, 0.9, colorSat);
3   c0.rgb = mix(c0.rgb, sat, delta);
    return c0;
}

The original shader, works on SDR and HDR

//!PARAM vibr
//!DESC Saturates/deSaturates
//!TYPE float
//!MINIMUM -1
-0.5

//!HOOK MAIN
//!BIND HOOKED
//!DESC Vibrance

#define CoefLuma vec4(0.2126, 0.7152, 0.0722, 0) //sRGB, HDTV
float Thresh = 200.0/255.0;
float w = 10.0/255.0;

vec4 hook() {
vec4 c0 = HOOKED_texOff(0);
float lum = (c0.r + c0.g + c0.b)/3.0; 

float colorSat = max(max(c0.r, c0.g), c0.b) -min(min(c0.r, c0.g), c0.b); // >=0, 5 arithmetic
vec3 sat = mix(vec3(dot(c0, CoefLuma)), c0.rgb, 1+vibr -colorSat*abs(vibr));
float delta = smoothstep( Thresh-w, Thresh+w, lum);
c0.rgb = mix( sat, c0.rgb, delta);
return c0;
}

[hizzlekizzle]

When you said it doesn't work, what does that mean? looks wrong? If so, can you post some comparison screenshots?

[geextahslex]

Hi, thank you for your answer. By that I mean that it visually doesn't change anything. The shader is working in the pipeline but there is no visible effect.

this is how it should look like, look at the blue suit color

this is how it looks now

[hizzlekizzle]

Hmm, that's a very subtle difference. Much too subtle for my crummy eyes and monitor lol

Have you tried doing a sanity check? That is, setting one of the values in your added lines to a very large value to make sure it's actually there and doing what it's supposed to?

[geextahslex]

Yes. I maxed out settings and changed them around but there is simply no change to the image. And as mentioned, it works on SDR but not HDR