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PicoGraphics/JPEGDEC: RGB332 per channel fast dither.

This commit is contained in:
Phil Howard 2022-06-10 10:00:35 +01:00
parent 602d1b41dd
commit 2419f0ef45
3 changed files with 59 additions and 12 deletions
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1
libraries/pico_graphics/pico_graphics.cpp
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@ -9,6 +9,7 @@ namespace pimoroni {
int PicoGraphics::create_pen(uint8_t r, uint8_t g, uint8_t b) {return -1;};
void PicoGraphics::set_pixel(const Point &p) {};
void PicoGraphics::set_pixel_dither(const Point &p, const RGB &c) {};
void PicoGraphics::set_pixel_dither(const Point &p, const RGB565 &c) {};
void PicoGraphics::scanline_convert(PenType type, conversion_callback_func callback) {};
void PicoGraphics::set_dimensions(int width, int height) {

62
libraries/pico_graphics/pico_graphics.hpp
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@ -183,6 +183,7 @@ namespace pimoroni {
virtual int create_pen(uint8_t r, uint8_t g, uint8_t b);
virtual void set_pixel(const Point &p);
virtual void set_pixel_dither(const Point &p, const RGB &c);
virtual void set_pixel_dither(const Point &p, const RGB565 &c);
virtual void scanline_convert(PenType type, conversion_callback_func callback);
void set_font(const bitmap::font_t *font);
@ -429,17 +430,62 @@ namespace pimoroni {
}
void set_pixel_dither(const Point &p, const RGB &c) override {
if(!bounds.contains(p)) return;
static uint pattern[16] = // dither pattern
{0, 8, 2, 10, 12, 4, 14, 6, 3, 11, 1, 9, 15, 7, 13, 5};
static uint8_t _odm[16] = {
0, 8, 2, 10,
12, 4, 14, 6,
3, 11, 1, 9,
15, 7, 13, 5
};
static std::array<uint8_t, 16> candidates;
get_dither_candidates(c, palette, 256, candidates);
uint8_t _dmv = _odm[(p.x & 0b11) | ((p.y & 0b11) << 2)];
// find the pattern coordinate offset
uint pattern_index = (p.x & 0b11) | ((p.y & 0b11) << 2);
uint8_t red = c.r & 0b11000000; // Two bits red
uint8_t red_r = c.r & 0b111111; // Remaining six bits red
red_r >>= 2; // Discard down to four bit
uint8_t grn = (c.g & 0b11000000) >> 3; // Two bits green
uint8_t grn_r = c.g & 0b111111; // Remaining six bits green
grn_r >>= 2; // Discard down to four bit
uint8_t blu = (c.b & 0b10000000) >> 6; // One bit blue
uint8_t blu_r = c.b & 0b1111111; // Remaining seven bits green
blu_r >>= 3; // Discard down to four bit
color = red | grn | blu;
if(red_r > _dmv) color |= 0b00100000;
if(grn_r > _dmv) color |= 0b00000100;
if(blu_r > _dmv) color |= 0b00000001;
set_pixel(p);
}
void set_pixel_dither(const Point &p, const RGB565 &c) override {
if(!bounds.contains(p)) return;
RGB565 cs = __builtin_bswap16(c);
static uint8_t _odm[16] = {
0, 8, 2, 10,
12, 4, 14, 6,
3, 11, 1, 9,
15, 7, 13, 5
};
uint8_t _dmv = _odm[(p.x & 0b11) | ((p.y & 0b11) << 2)];
// RRRRRGGGGGGBBBBB
uint8_t red = (cs & 0b1100000000000000) >> 8; // Two bits grn
uint8_t red_r = (cs & 0b0011100000000000) >> 10; // Four bits cmp
uint8_t grn = (cs & 0b0000011000000000) >> 6; // Two bit grn
uint8_t grn_r = (cs & 0b0000000111100000) >> 5; // Four bit cmp
uint8_t blu = (cs & 0b0000000000010000) >> 3; // Two bit blu
uint8_t blu_r = (cs & 0b0000000000001111); // Four bit cmp
color = red | grn | blu;
// RRRGGGBB
if(red_r > _dmv) color |= 0b00100000;
if(grn_r > _dmv) color |= 0b00000100;
if(blu_r > _dmv) color |= 0b00000001;
// set the pixel
color = candidates[pattern[pattern_index]];
set_pixel(p);
}
void scanline_convert(PenType type, conversion_callback_func callback) override {

8
micropython/modules/jpegdec/jpegdec.cpp
View File

@ -61,10 +61,10 @@ MICROPY_EVENT_POLL_HOOK
for(int x = 0; x < pDraw->iWidth; x++) {
int i = y * pDraw->iWidth + x;
if (current_graphics->pen_type == PicoGraphics::PEN_RGB332) {
current_graphics->set_pen(RGB((RGB565)pDraw->pPixels[i]).to_rgb332());
current_graphics->pixel({pDraw->x + x, pDraw->y + y});
// FIXME VERY, VERY SLOW!
//current_graphics->set_pixel_dither({pDraw->x + x, pDraw->y + y}, RGB((RGB565)(pDraw->pPixels[i])));
//current_graphics->set_pen(RGB((RGB565)pDraw->pPixels[i]).to_rgb332());
//current_graphics->pixel({pDraw->x + x, pDraw->y + y});
// TODO make dither optional
current_graphics->set_pixel_dither({pDraw->x + x, pDraw->y + y}, (RGB565)(pDraw->pPixels[i]));
} else {
current_graphics->set_pen(pDraw->pPixels[i]);
current_graphics->pixel({pDraw->x + x, pDraw->y + y});