From fe006cfef796b2fd6a391eeb6e71f3caa333fe1e Mon Sep 17 00:00:00 2001
From: Micah Elizabeth Scott <micah@scanlime.org>
Date: Thu, 18 Jul 2013 21:54:57 -0700
Subject: [PATCH] Tweaks to dithering algorithm
Damping to reduce oscillation, more realistic (larger-scale) test.
---
src/hcolor.h | 8 +++++---
src/main.cpp | 6 +++---
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/src/hcolor.h b/src/hcolor.h
index 45f7c7d..adbe490 100644
--- a/src/hcolor.h
+++ b/src/hcolor.h
@@ -94,9 +94,9 @@ struct HPixel {
uint32_t dither() {
// Incorporate the residual from last frame
- int r16 = color.r + residual[0];
- int g16 = color.g + residual[1];
- int b16 = color.b + residual[2];
+ int r16 = color.r + (residual[0] >> 1);
+ int g16 = color.g + (residual[1] >> 1);
+ int b16 = color.b + (residual[2] >> 1);
// Round to the nearest 8-bit value
int r8 = std::min<int>(0xff, std::max<int>(0, (r16 + 0x80) >> 8));
@@ -104,9 +104,11 @@ struct HPixel {
int b8 = std::min<int>(0xff, std::max<int>(0, (b16 + 0x80) >> 8));
// Compute the error, after expanding the 8-bit value back to 16-bit.
+ #if 1
residual[0] = r16 - (r8 * 257);
residual[1] = g16 - (g8 * 257);
residual[2] = b16 - (b8 * 257);
+ #endif
return (r8 << 16) | (g8 << 8) | b8;
}
diff --git a/src/main.cpp b/src/main.cpp
index 5875c65..92e7dcc 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -9,7 +9,7 @@
#include <math.h>
#include "hcolor.h"
-static const int ledsPerStrip = 16;
+static const int ledsPerStrip = 64;
static const int ledsTotal = ledsPerStrip * 8;
DMAMEM int displayMemory[ledsPerStrip * 6];
@@ -30,13 +30,13 @@ void setup()
void loop()
{
// XXX: Proof of concept
-
+
for (int i = 0; i < 16; i++) {
unsigned c = pow(sin(i * 0.2 + millis() * 0.0005) * 0.5 + 0.5, 2.2) * 0x1000;
pixbuf.pixels[i].color = HColor16(c>>2, c, c>>1);
}
- for (int i = 0; i < 1000; i++) {
+ for (int i = 0; i < 100; i++) {
pixbuf.show(leds);
}
}
--
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