Move options for dithering and brightness to run time, fix BMP.

This commit is contained in:
Jonas Diemer 2026-01-09 14:39:04 +01:00
parent d4ae108d9b
commit 7838660ff5
3 changed files with 23 additions and 25 deletions

View File

@ -8,12 +8,9 @@
// ============================================================================ // ============================================================================
// Note: For cover images, dithering is done in JpegToBmpConverter.cpp // Note: For cover images, dithering is done in JpegToBmpConverter.cpp
// This file handles BMP reading - use simple quantization to avoid double-dithering // This file handles BMP reading - use simple quantization to avoid double-dithering
constexpr bool USE_FLOYD_STEINBERG = false; // Disabled - dithering done at JPEG conversion // constexpr bool USE_FLOYD_STEINBERG = true; // Disabled - dithering done at JPEG conversion
constexpr bool USE_NOISE_DITHERING = false; // Hash-based noise dithering constexpr bool USE_NOISE_DITHERING = false; // Hash-based noise dithering
// Brightness adjustments: constexpr bool GAMMA_CORRECTION = true; // Gamma curve, only if USE_BRIGHTNESS=true
constexpr bool USE_BRIGHTNESS = false; // true: apply brightness/gamma adjustments
constexpr int BRIGHTNESS_BOOST = 20; // Brightness offset (0-50), only if USE_BRIGHTNESS=true
constexpr bool GAMMA_CORRECTION = false; // Gamma curve, only if USE_BRIGHTNESS=true
// ============================================================================ // ============================================================================
// Integer approximation of gamma correction (brightens midtones) // Integer approximation of gamma correction (brightens midtones)
@ -28,24 +25,19 @@ static inline int applyGamma(int gray) {
return x > 255 ? 255 : x; return x > 255 ? 255 : x;
} }
// Simple quantization without dithering - just divide into 4 levels static inline uint8_t boostBrightness(int gray, uint8_t boost) {
static inline uint8_t quantizeSimple(int gray) { if (boost > 0) {
if (USE_BRIGHTNESS) { gray += boost;
gray += BRIGHTNESS_BOOST;
if (gray > 255) gray = 255; if (gray > 255) gray = 255;
gray = applyGamma(gray); gray = applyGamma(gray);
} }
return static_cast<uint8_t>(gray >> 6); return gray;
} }
// Simple quantization without dithering - just divide into 4 levels
static inline uint8_t quantizeSimple(int gray) { return static_cast<uint8_t>(gray >> 6); }
// Hash-based noise dithering - survives downsampling without moiré artifacts // Hash-based noise dithering - survives downsampling without moiré artifacts
static inline uint8_t quantizeNoise(int gray, int x, int y) { static inline uint8_t quantizeNoise(int gray, int x, int y) {
if (USE_BRIGHTNESS) {
gray += BRIGHTNESS_BOOST;
if (gray > 255) gray = 255;
gray = applyGamma(gray);
}
uint32_t hash = static_cast<uint32_t>(x) * 374761393u + static_cast<uint32_t>(y) * 668265263u; uint32_t hash = static_cast<uint32_t>(x) * 374761393u + static_cast<uint32_t>(y) * 668265263u;
hash = (hash ^ (hash >> 13)) * 1274126177u; hash = (hash ^ (hash >> 13)) * 1274126177u;
const int threshold = static_cast<int>(hash >> 24); const int threshold = static_cast<int>(hash >> 24);
@ -75,7 +67,6 @@ static inline uint8_t quantizeFloydSteinberg(int gray, int x, int width, int16_t
bool reverseDir) { bool reverseDir) {
// Add accumulated error to this pixel // Add accumulated error to this pixel
int adjusted = gray + errorCurRow[x + 1]; int adjusted = gray + errorCurRow[x + 1];
// Clamp to valid range // Clamp to valid range
if (adjusted < 0) adjusted = 0; if (adjusted < 0) adjusted = 0;
if (adjusted > 255) adjusted = 255; if (adjusted > 255) adjusted = 255;
@ -245,7 +236,7 @@ BmpReaderError Bitmap::parseHeaders() {
} }
// Allocate Floyd-Steinberg error buffers if enabled // Allocate Floyd-Steinberg error buffers if enabled
if (USE_FLOYD_STEINBERG) { if (useFloydSteinberg) {
delete[] errorCurRow; delete[] errorCurRow;
delete[] errorNextRow; delete[] errorNextRow;
errorCurRow = new int16_t[width + 2](); // +2 for boundary handling errorCurRow = new int16_t[width + 2](); // +2 for boundary handling
@ -262,7 +253,7 @@ BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
if (file.read(rowBuffer, rowBytes) != rowBytes) return BmpReaderError::ShortReadRow; if (file.read(rowBuffer, rowBytes) != rowBytes) return BmpReaderError::ShortReadRow;
// Handle Floyd-Steinberg error buffer progression // Handle Floyd-Steinberg error buffer progression
const bool useFS = USE_FLOYD_STEINBERG && errorCurRow && errorNextRow; const bool useFS = useFloydSteinberg && errorCurRow && errorNextRow;
if (useFS) { if (useFS) {
if (prevRowY != -1) { if (prevRowY != -1) {
// Sequential access - swap buffers // Sequential access - swap buffers
@ -284,10 +275,12 @@ BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
uint8_t color; uint8_t color;
if (useFS) { if (useFS) {
// Floyd-Steinberg error diffusion // Floyd-Steinberg error diffusion
color = quantizeFloydSteinberg(lum, currentX, width, errorCurRow, errorNextRow, false); color = quantizeFloydSteinberg(boostBrightness(lum, brightnessBoost), currentX, width, errorCurRow, errorNextRow,
false);
} else { } else {
// Simple quantization or noise dithering // Simple quantization or noise dithering
color = quantize(lum, currentX, prevRowY);
color = quantize(boostBrightness(lum, brightnessBoost), currentX, prevRowY);
} }
currentOutByte |= (color << bitShift); currentOutByte |= (color << bitShift);
if (bitShift == 0) { if (bitShift == 0) {
@ -357,7 +350,7 @@ BmpReaderError Bitmap::rewindToData() const {
} }
// Reset Floyd-Steinberg error buffers when rewinding // Reset Floyd-Steinberg error buffers when rewinding
if (USE_FLOYD_STEINBERG && errorCurRow && errorNextRow) { if (useFloydSteinberg && errorCurRow && errorNextRow) {
memset(errorCurRow, 0, (width + 2) * sizeof(int16_t)); memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
memset(errorNextRow, 0, (width + 2) * sizeof(int16_t)); memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
prevRowY = -1; prevRowY = -1;

View File

@ -2,6 +2,8 @@
#include <SdFat.h> #include <SdFat.h>
#include <cstdint>
enum class BmpReaderError : uint8_t { enum class BmpReaderError : uint8_t {
Ok = 0, Ok = 0,
FileInvalid, FileInvalid,
@ -28,7 +30,8 @@ class Bitmap {
public: public:
static const char* errorToString(BmpReaderError err); static const char* errorToString(BmpReaderError err);
explicit Bitmap(FsFile& file) : file(file) {} explicit Bitmap(FsFile& file, bool useFloydSteinberg = false, uint8_t brightnessBoost = 0)
: file(file), useFloydSteinberg(useFloydSteinberg), brightnessBoost(brightnessBoost) {}
~Bitmap(); ~Bitmap();
BmpReaderError parseHeaders(); BmpReaderError parseHeaders();
BmpReaderError readNextRow(uint8_t* data, uint8_t* rowBuffer) const; BmpReaderError readNextRow(uint8_t* data, uint8_t* rowBuffer) const;
@ -44,6 +47,8 @@ class Bitmap {
static uint32_t readLE32(FsFile& f); static uint32_t readLE32(FsFile& f);
FsFile& file; FsFile& file;
bool useFloydSteinberg = false;
uint8_t brightnessBoost = 0;
int width = 0; int width = 0;
int height = 0; int height = 0;
bool topDown = false; bool topDown = false;

View File

@ -86,7 +86,7 @@ void SleepActivity::renderCustomSleepScreen() const {
if (SdMan.openFileForRead("SLP", filename, file)) { if (SdMan.openFileForRead("SLP", filename, file)) {
Serial.printf("[%lu] [SLP] Randomly loading: /sleep/%s\n", millis(), files[randomFileIndex].c_str()); Serial.printf("[%lu] [SLP] Randomly loading: /sleep/%s\n", millis(), files[randomFileIndex].c_str());
delay(100); delay(100);
Bitmap bitmap(file); Bitmap bitmap(file, true, 50);
if (bitmap.parseHeaders() == BmpReaderError::Ok) { if (bitmap.parseHeaders() == BmpReaderError::Ok) {
renderBitmapSleepScreen(bitmap); renderBitmapSleepScreen(bitmap);
dir.close(); dir.close();
@ -101,7 +101,7 @@ void SleepActivity::renderCustomSleepScreen() const {
// render a custom sleep screen instead of the default. // render a custom sleep screen instead of the default.
FsFile file; FsFile file;
if (SdMan.openFileForRead("SLP", "/sleep.bmp", file)) { if (SdMan.openFileForRead("SLP", "/sleep.bmp", file)) {
Bitmap bitmap(file); Bitmap bitmap(file, true, 50);
if (bitmap.parseHeaders() == BmpReaderError::Ok) { if (bitmap.parseHeaders() == BmpReaderError::Ok) {
Serial.printf("[%lu] [SLP] Loading: /sleep.bmp\n", millis()); Serial.printf("[%lu] [SLP] Loading: /sleep.bmp\n", millis());
renderBitmapSleepScreen(bitmap); renderBitmapSleepScreen(bitmap);