From 0e44d6d2146aa6e52a1c5f8de79da73f6a9aa080 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 8 Sep 2020 16:19:08 -0400
Subject: [PATCH] Experiments with an all-box filter.
---
.../Clock Signal/ScanTarget/CSScanTarget.mm | 24 ++++++++++++-------
.../Clock Signal/ScanTarget/ScanTarget.metal | 5 ++--
2 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
index 0c731be88..510bc9717 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
@@ -135,6 +135,8 @@ constexpr MTLResourceOptions SharedResourceOptionsTexture = MTLResourceCPUCacheM
} \
}
+/// @returns the proper 1d kernel to apply a box filter around a certain point a pixel density of @c radiansPerPixel and applying an
+/// angular limit of @c cutoff. The values returned will be the first eight of a fifteen-point filter that is symmetrical around its centre.
std::array<float, 8> boxCoefficients(float radiansPerPixel, float cutoff) {
std::array<float, 8> filter;
float total = 0.0f;
@@ -155,7 +157,7 @@ std::array<float, 8> boxCoefficients(float radiansPerPixel, float cutoff) {
total += 2.0f * coefficient; // All but the centre coefficient will be used twice.
filter[c] = coefficient;
}
- total = (total - filter[7]) / 2.0f; // As per above; ensure the centre coefficient is counted only once.
+ total = total - filter[7]; // As per above; ensure the centre coefficient is counted only once.
for(size_t c = 0; c < 8; ++c) {
filter[c] /= total;
@@ -651,9 +653,9 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
// Generate the chrominance filter.
{
auto *const firCoefficients = uniforms()->chromaCoefficients;
- const auto chromaCoefficients = boxCoefficients(uniforms()->radiansPerPixel, 3.141592654f);
+ const auto chromaCoefficients = boxCoefficients(uniforms()->radiansPerPixel, 3.141592654f * 0.5f);
for(size_t c = 0; c < 8; ++c) {
- firCoefficients[c].y = firCoefficients[c].z = chromaCoefficients[c] / 2.0f;
+ firCoefficients[c].y = firCoefficients[c].z = (isSVideoOutput ? 2.0f : 1.0f) * chromaCoefficients[c];
firCoefficients[c].x = 0.0f;
}
firCoefficients[7].x = 1.0f;
@@ -665,10 +667,11 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
//
// The low cut off ['Hz' but per line, not per second] is somewhat arbitrary.
if(!isSVideoOutput) {
-// SignalProcessing::FIRFilter sharpenFilter(15, float(_lineBufferPixelsPerLine), 40.0f, colourCyclesPerLine);
+// SignalProcessing::FIRFilter sharpenFilter(15, float(_lineBufferPixelsPerLine), 80.0f, colourCyclesPerLine * 0.5f);
// const auto sharpen = sharpenFilter.get_coefficients();
// for(size_t c = 0; c < 8; ++c) {
-// chromaCoefficients[c].x = sharpen[c];
+// firCoefficients[c].x = firCoefficients[c].y;
+// firCoefficients[c].x = sharpen[c];
// }
}
}
@@ -676,13 +679,16 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
// Generate the luminance separation filter.
{
auto *const firCoefficients = uniforms()->lumaCoefficients;
- SignalProcessing::FIRFilter lumaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.6f);
+ SignalProcessing::FIRFilter lumaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.5f);
// SignalProcessing::FIRFilter chromaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.5f);
- const auto chromaCoefficients = lumaPart.get_coefficients();
- const auto lumaCoefficients = boxCoefficients(uniforms()->radiansPerPixel, 3.141592654f);//chromaPart.get_coefficients();
+// const auto chromaCoefficients = lumaPart.get_coefficients();
+// const auto lumaCoefficients = lumaPart.get_coefficients();
+ const auto chromaCoefficients = boxCoefficients(uniforms()->radiansPerPixel, 3.141592654f);//chromaPart.get_coefficients();
+ const auto lumaCoefficients = lumaPart.get_coefficients();
+// const auto chromaCoefficients = lumaCoefficients;
for(size_t c = 0; c < 8; ++c) {
- firCoefficients[c].x = lumaCoefficients[c];
+ firCoefficients[c].x = //lumaCoefficients[c];
firCoefficients[c].y = chromaCoefficients[c];
}
}
diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
index 86fca8550..98f6df2f0 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
@@ -484,8 +484,9 @@ kernel void separateLumaKernel( texture2d<float, access::read> inTexture [[textu
const float isColour = step(0.01, centreSample.a);
const float chroma = (centreSample.r - luminance.g) / mix(1.0f, centreSample.a, isColour);
outTexture.write(float4(
- mix(luminance.g, luminance.r / (1.0f - centreSample.a), isColour),
-// luminance.r / mix(1.0f, (1.0f - centreSample.a), isColour),
+// mix(luminance.g, luminance.r / (1.0f - centreSample.a), isColour),
+ luminance.r / mix(1.0f, (1.0f - centreSample.a), isColour),
+// luminance.r,
isColour * (centreSample.gb - float2(0.5f)) * chroma + float2(0.5f),
1.0f
),