mirror of
https://github.com/RetroDECK/Duckstation.git
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252 lines
9.3 KiB
HLSL
252 lines
9.3 KiB
HLSL
/**
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* Deband shader by haasn
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* https://github.com/haasn/gentoo-conf/blob/xor/home/nand/.mpv/shaders/deband-pre.glsl
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*
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* Copyright (c) 2015 Niklas Haas
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* Modified and optimized for ReShade by JPulowski
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* https://reshade.me/forum/shader-presentation/768-deband
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*
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* Do not distribute without giving credit to the original author(s).
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*
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* 1.0 - Initial release
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* 1.1 - Replaced the algorithm with the one from MPV
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* 1.1a - Minor optimizations
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* - Removed unnecessary lines and replaced them with ReShadeFX intrinsic counterparts
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* 2.0 - Replaced "grain" with CeeJay.dk's ordered dithering algorithm and enabled it by default
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* - The configuration is now more simpler and straightforward
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* - Some minor code changes and optimizations
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* - Improved the algorithm and made it more robust by adding some of the madshi's
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* improvements to flash3kyuu_deband which should cause an increase in quality. Higher
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* iterations/ranges should now yield higher quality debanding without too much decrease
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* in quality.
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* - Changed licensing text and original source code URL
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* 3.0 - Replaced the entire banding detection algorithm with modified standard deviation and
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* Weber ratio analyses which give more accurate and error-free results compared to the
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* previous algorithm
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* - Added banding map debug view
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* - Added and redefined UI categories
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* - Added depth detection (credits to spiro) which should be useful when banding only
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* occurs in the sky texture for example
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* - Fixed a bug in random number generation which was causing artifacts on the upper left
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* side of the screen
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* - Dithering is now applied only when debanding a pixel as it should be which should
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* reduce the overall noise in the final texture
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* - Minor code optimizations
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* 3.1 - Switched to chroma-based analysis from luma-based analysis which was causing artifacts
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* under some scenarios
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* - Changed parts of the code which was causing compatibility issues on some renderers
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*/
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#include "ReShadeUI.fxh"
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#include "ReShade.fxh"
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uniform bool enable_weber <
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ui_category = "Banding analysis";
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ui_label = "Weber ratio";
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ui_tooltip = "Weber ratio analysis that calculates the ratio of the each local pixel's intensity to average background intensity of all the local pixels.";
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ui_type = "radio";
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> = true;
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uniform bool enable_sdeviation <
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ui_category = "Banding analysis";
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ui_label = "Standard deviation";
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ui_tooltip = "Modified standard deviation analysis that calculates nearby pixels' intensity deviation from the current pixel instead of the mean.";
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ui_type = "radio";
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> = true;
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uniform bool enable_depthbuffer <
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ui_category = "Banding analysis";
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ui_label = "Depth detection";
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ui_tooltip = "Allows depth information to be used when analysing banding, pixels will only be analysed if they are in a certain depth. (e.g. debanding only the sky)";
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ui_type = "radio";
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> = false;
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uniform float t1 <
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ui_category = "Banding analysis";
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ui_label = "Standard deviation threshold";
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ui_max = 0.5;
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ui_min = 0.0;
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ui_step = 0.001;
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ui_tooltip = "Standard deviations lower than this threshold will be flagged as flat regions with potential banding.";
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ui_type = "slider";
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> = 0.007;
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uniform float t2 <
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ui_category = "Banding analysis";
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ui_label = "Weber ratio threshold";
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ui_max = 2.0;
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ui_min = 0.0;
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ui_step = 0.01;
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ui_tooltip = "Weber ratios lower than this threshold will be flagged as flat regions with potential banding.";
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ui_type = "slider";
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> = 0.04;
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uniform float banding_depth <
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ui_category = "Banding analysis";
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ui_label = "Banding depth";
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ui_max = 1.0;
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ui_min = 0.0;
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ui_step = 0.001;
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ui_tooltip = "Pixels under this depth threshold will not be processed and returned as they are.";
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ui_type = "slider";
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> = 1.0;
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uniform float range <
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ui_category = "Banding detection & removal";
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ui_label = "Radius";
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ui_max = 32.0;
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ui_min = 1.0;
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ui_step = 1.0;
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ui_tooltip = "The radius increases linearly for each iteration. A higher radius will find more gradients, but a lower radius will smooth more aggressively.";
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ui_type = "slider";
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> = 24.0;
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uniform int iterations <
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ui_category = "Banding detection & removal";
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ui_label = "Iterations";
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ui_max = 4;
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ui_min = 1;
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ui_tooltip = "The number of debanding steps to perform per sample. Each step reduces a bit more banding, but takes time to compute.";
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ui_type = "slider";
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> = 1;
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uniform int debug_output <
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ui_category = "Debug";
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ui_items = "None\0Blurred (LPF) image\0Banding map\0";
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ui_label = "Debug view";
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ui_tooltip = "Blurred (LPF) image: Useful when tweaking radius and iterations to make sure all banding regions are blurred enough.\nBanding map: Useful when tweaking analysis parameters, continuous green regions indicate flat (i.e. banding) regions.";
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ui_type = "combo";
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> = 0;
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// Reshade uses C rand for random, max cannot be larger than 2^15-1
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uniform int drandom < source = "random"; min = 0; max = 32767; >;
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float rand(float x)
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{
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return frac(x / 41.0);
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}
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float permute(float x)
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{
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return ((34.0 * x + 1.0) * x) % 289.0;
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}
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float3 PS_Deband(float4 vpos : SV_Position, float2 texcoord : TexCoord) : SV_Target
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{
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float3 ori = tex2Dlod(ReShade::BackBuffer, float4(texcoord, 0.0, 0.0)).rgb;
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if (enable_depthbuffer && (ReShade::GetLinearizedDepth(texcoord) < banding_depth))
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return ori;
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// Initialize the PRNG by hashing the position + a random uniform
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float3 m = float3(texcoord + 1.0, (drandom / 32767.0) + 1.0);
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float h = permute(permute(permute(m.x) + m.y) + m.z);
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// Compute a random angle
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float dir = rand(permute(h)) * 6.2831853;
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float2 o;
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sincos(dir, o.y, o.x);
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// Distance calculations
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float2 pt;
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float dist;
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for (int i = 1; i <= iterations; ++i) {
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dist = rand(h) * range * i;
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pt = dist * BUFFER_PIXEL_SIZE;
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h = permute(h);
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}
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// Sample at quarter-turn intervals around the source pixel
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float3 ref[4] = {
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tex2Dlod(ReShade::BackBuffer, float4(mad(pt, o, texcoord), 0.0, 0.0)).rgb, // SE
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tex2Dlod(ReShade::BackBuffer, float4(mad(pt, -o, texcoord), 0.0, 0.0)).rgb, // NW
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tex2Dlod(ReShade::BackBuffer, float4(mad(pt, float2(-o.y, o.x), texcoord), 0.0, 0.0)).rgb, // NE
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tex2Dlod(ReShade::BackBuffer, float4(mad(pt, float2( o.y, -o.x), texcoord), 0.0, 0.0)).rgb // SW
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};
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// Calculate weber ratio
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float3 mean = (ori + ref[0] + ref[1] + ref[2] + ref[3]) * 0.2;
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float3 k = abs(ori - mean);
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for (int j = 0; j < 4; ++j) {
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k += abs(ref[j] - mean);
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}
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k = k * 0.2 / mean;
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// Calculate std. deviation
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float3 sd = 0.0;
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for (int j = 0; j < 4; ++j) {
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sd += pow(ref[j] - ori, 2);
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}
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sd = sqrt(sd * 0.25);
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// Generate final output
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float3 output;
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if (debug_output == 2)
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output = float3(0.0, 1.0, 0.0);
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else
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output = (ref[0] + ref[1] + ref[2] + ref[3]) * 0.25;
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// Generate a binary banding map
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bool3 banding_map = true;
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if (debug_output != 1) {
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if (enable_weber)
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banding_map = banding_map && k <= t2 * iterations;
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if (enable_sdeviation)
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banding_map = banding_map && sd <= t1 * iterations;
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}
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/*------------------------.
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| :: Ordered Dithering :: |
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'------------------------*/
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//Calculate grid position
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float grid_position = frac(dot(texcoord, (BUFFER_SCREEN_SIZE * float2(1.0 / 16.0, 10.0 / 36.0)) + 0.25));
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//Calculate how big the shift should be
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float dither_shift = 0.25 * (1.0 / (pow(2, BUFFER_COLOR_BIT_DEPTH) - 1.0));
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//Shift the individual colors differently, thus making it even harder to see the dithering pattern
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float3 dither_shift_RGB = float3(dither_shift, -dither_shift, dither_shift); //subpixel dithering
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//modify shift acording to grid position.
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dither_shift_RGB = lerp(2.0 * dither_shift_RGB, -2.0 * dither_shift_RGB, grid_position); //shift acording to grid position.
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return banding_map ? output + dither_shift_RGB : ori;
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}
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technique Deband <
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ui_tooltip = "Alleviates color banding by trying to approximate original color values.";
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>
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{
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pass
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{
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VertexShader = PostProcessVS;
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PixelShader = PS_Deband;
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}
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} |