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Switches to dynamic generation of the 'sharpness' filter, correcting issues with the Apple II (amongst others).

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This commit is contained in:
Thomas Harte 2020-09-03 20:48:44 -04:00
parent 74d0acdaec
commit 5cd8d86eef
1 changed files with 10 additions and 16 deletions
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26
OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
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@ -575,24 +575,20 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
SignalProcessing::FIRFilter chrominancefilter(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.01f);
const auto calculatedChromaCoefficients = chrominancefilter.get_coefficients();
for(size_t c = 0; c < 8; ++c) {
chromaCoefficients[c].y = chromaCoefficients[c].z = calculatedChromaCoefficients[c] * (isSVideoOutput ? 4.0f : 2.0f);
chromaCoefficients[c].y = chromaCoefficients[c].z = calculatedChromaCoefficients[c] * (isSVideoOutput ? 4.0f : 3.0f);
chromaCoefficients[c].x = 0.0f;
}
chromaCoefficients[7].x = 1.0f;
// Luminance will be very soft as a result of the separation phase; apply a sharpen filter to try to undo that.
// This is applied separately because the first composite processing step is going to select between the nominal
// chroma and luma parts to take the place of luminance depending on whether a colour burst was found, and high-pass
// filtering the chrominance channel would be visually detrimental.
//
// The 30 ['Hz' but per line, not per second] is somewhat arbitrary.
if(!isSVideoOutput) {
constexpr float sharpen[] = {
0.0042115543f,
0.0f,
-0.0641804263f,
-0.252418578f,
-0.589709163f,
0.987914681f,
0.627704679f,
-0.426862389f,
0.627704679f
};
SignalProcessing::FIRFilter sharpenFilter(15, float(_lineBufferPixelsPerLine), 20.0f, colourCyclesPerLine);
const auto sharpen = sharpenFilter.get_coefficients();
for(size_t c = 0; c < 8; ++c) {
chromaCoefficients[c].x = sharpen[c];
}
@ -601,11 +597,9 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
// Generate the luminance separation filter.
{
// TODO: support separate high-low filters for chroma and luma, rather than treating that as purely subtractive.
auto *const luminanceCoefficients = uniforms()->lumaCoefficients;
SignalProcessing::FIRFilter lumaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.75f);
SignalProcessing::FIRFilter chromaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 1.0f);
SignalProcessing::FIRFilter lumaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 0.6f);
SignalProcessing::FIRFilter chromaPart(15, float(_lineBufferPixelsPerLine), 0.0f, colourCyclesPerLine * 1.25f);
const auto lumaCoefficients = lumaPart.get_coefficients();
const auto chromaCoefficients = chromaPart.get_coefficients();