initial atari tests (not with image) and dither improvements

palette selection now biases to matches on the bright side of
the RGB color cube, since black is always available for dithering

does better but still not perfect

atari binary just writes some test data to text framebuffer
but builds and runs
This commit is contained in:
Brooke Vibber 2022-11-20 15:43:34 -08:00
parent 1f70e107cd
commit 94a2e40504
3 changed files with 93 additions and 12 deletions

19
Makefile Normal file
View file

@ -0,0 +1,19 @@
.PHONY : all clean
all : dither4.xex
# sample5.s from sample5.jpg
# reminder: $< is input
# $@ is output
%.o : %.s
ca65 -v -t atari -o $@ $<
dither4.xex : dither4.o
ld65 -v -C atari-asm-xex.cfg -o $@ $<
clean :
rm -f sample5.s
rm -f sample5.o
rm -f dither4.o
rm -f dither4.xex

View file

@ -388,15 +388,19 @@ function decimate(input, palette, n) {
for (let x = 0; x < line.length; x++) {
let rgb = line[x];
rgb = rgb.add(error.right);
rgb.cap();
//rgb.cap();
// find the closest possible color
let shortest = Infinity;
let pick = -1;
let pick = 1;
for (let i = 0; i < palette.length; i++) {
let diff = rgb.difference(palette[i]);
let dist = diff.magnitude();
let darker = Math.min(diff.r, diff.g, diff.b) < 0;
if (darker) {
dist **= 2;
}
if (dist < shortest) {
nextError = diff;
shortest = dist;
@ -430,7 +434,6 @@ function decimate(input, palette, n) {
error.blue[x] += nextError.b / 2;
*/
/*
error.right.r = nextError.r / 2;
error.right.g = nextError.g / 2;
error.right.b = nextError.b / 2;
@ -446,8 +449,8 @@ function decimate(input, palette, n) {
error.red[x + 1] += nextError.r / 8;
error.green[x + 1] += nextError.g / 8;
error.blue[x + 1] += nextError.b / 8;
*/
/*
error.right.r = nextError.r / 4;
error.right.g = nextError.g / 4;
error.right.b = nextError.b / 4;
@ -463,9 +466,20 @@ function decimate(input, palette, n) {
error.red[x + 1] += nextError.r / 4;
error.green[x + 1] += nextError.g / 4;
error.blue[x + 1] += nextError.b / 4;
*/
// 442 is the 3d distance across the rgb cube
fitness[x] = 442 - (nextError.magnitude());
//fitness[x] = 442 - (nextError.magnitude());
//fitness[x] = 442 / (442 - nextError.magnitude());
fitness[x] = 255 / (256 - Math.max(nextError.r, nextError.g, nextError.b));
/*
fitness[x] = Math.max(
255 - Math.abs(nextError.r),
255 - Math.abs(nextError.g),
255 - Math.abs(nextError.b),
);
*/
}
return {
output,
@ -476,8 +490,37 @@ function decimate(input, palette, n) {
};
};
// black, red, blue, white
let rbw = [
palette256[0x00],
palette256[0x87],
palette256[0xf7],
palette256[0x0f],
];
let rgb = [
palette256[0x00],
palette256[0x87],
palette256[0xc7],
palette256[0xf7],
];
// grayscale
let gray = [
palette256[0x00],
palette256[0x05],
palette256[0x0a],
palette256[0x0f],
];
//palette = rgb;
//palette = rbw;
//palette = gray;
let start = Date.now();
let decimated = palette.slice();
while (decimated.length > n) {
let {popularity, fitness, output} = dither(decimated);
@ -489,21 +532,17 @@ function decimate(input, palette, n) {
continue; // keep black always
}
if (decimated[i].r == 255 && decimated[i].g == 255 && decimated[i].b == 255) {
continue; // keep white always
//continue; // keep white always
}
let coolFactor = popularity[i];
/*
//let coolFactor = popularity[i];
let coolFactor = 0;
for (let x = 0; x < line.length; x++) {
if (output[x] == i) {
coolFactor += fitness[x];
coolFactor += fitness[x] ** 3;
}
}
coolFactor /= Math.sqrt(popularity[i]);
*/
if (coolFactor < least) {
pick = i;

23
dither4.s Normal file
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@ -0,0 +1,23 @@
SAVMSC = $58
.code
.export start
.proc start
; Get the framebuffer address and just write new fun values into it
; x: byte to write in
; y: index into the first 256 bytes of buffer
ldx #00
outer_loop:
txa
ldy #00
inner_loop:
sta (SAVMSC),y
iny
bne inner_loop
inx
jmp outer_loop
; infinite loop
.endproc