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Remove QOI_RUN_16, add new QOI_GDIFF_16 op

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This commit is contained in:
Dominic Szablewski 2021-11-30 22:05:03 +01:00
parent e9069e11a4
commit cbb62ea555
1 changed files with 89 additions and 76 deletions
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123
qoi.h
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@ -122,24 +122,14 @@ The possible chunks are:
6-bit index into the color index array: 0..63 6-bit index into the color index array: 0..63
- QOI_RUN_8 ------------- - QOI_RUN ---------------
| Byte[0] | | Byte[0] |
| 7 6 5 4 3 2 1 0 | | 7 6 5 4 3 2 1 0 |
|----------+--------------| |-------+-----------------|
| 0 1 0 | run | | 0 1 | run |
3-bit tag b010 2-bit tag b01
5-bit run-length repeating the previous pixel: 1..32 6-bit run-length repeating the previous pixel: 1..64
- QOI_RUN_16 --------------------------------------
| Byte[0] | Byte[1] |
| 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 |
|----------+----------------------------------------|
| 0 1 1 | run |
3-bit tag b011
13-bit run-length repeating the previous pixel: 33..8224
- QOI_DIFF_8 ------------ - QOI_DIFF_8 ------------
@ -160,14 +150,33 @@ so "1 - 2" will result in 255, while "255 + 1" will result in 0.
- QOI_DIFF_16 ------------------------------------- - QOI_DIFF_16 -------------------------------------
| Byte[0] | Byte[1] | | Byte[0] | Byte[1] |
| 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 | | 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 |
|----------+--------------|------------ +-----------| |-------------+-----------|------------ +-----------|
| 1 1 0 | red diff | green diff | blue diff | | 1 1 0 0 | red diff | green diff | blue diff |
3-bit tag b110 4-bit tag b1100
5-bit red channel difference from the previous pixel between -16..15 4-bit red channel difference from the previous pixel between -8..7
4-bit green channel difference from the previous pixel between -8..7 4-bit green channel difference from the previous pixel between -8..7
4-bit blue channel difference from the previous pixel between -8..7 4-bit blue channel difference from the previous pixel between -8..7
The difference to the current channel values are using a wraparound operation,
so "5 - 8" will result in 253, while "250 + 7" will result in 1.
- QOI_GDIFF_16 ------------------------------------
| Byte[0] | Byte[1] |
| 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 |
|-------------+--------+-------------------+--------|
| 1 1 0 1 | dr-dg | green diff | db-dg |
4-bit tag b1101
3-bit red channel difference minus green channel difference -4..3
6-bit green channel difference from the previous pixel -32..31
3-bit blue channel difference minus green channel difference -4..3
The green channel is used to indicate the general direction of change and gets
a few more bits. dr and db base their diffs off of the green channel diff. E.g.
dr = (last_px.r - cur_px.r) - (last_px.g - cur_px.g)
The difference to the current channel values are using a wraparound operation, The difference to the current channel values are using a wraparound operation,
so "10 - 13" will result in 253, while "250 + 7" will result in 1. so "10 - 13" will result in 253, while "250 + 7" will result in 1.
@ -310,15 +319,14 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels);
#endif #endif
#define QOI_INDEX 0x00 // 00xxxxxx #define QOI_INDEX 0x00 // 00xxxxxx
#define QOI_RUN_8 0x40 // 010xxxxx #define QOI_RUN 0x40 // 01xxxxxx
#define QOI_RUN_16 0x60 // 011xxxxx
#define QOI_DIFF_8 0x80 // 10xxxxxx #define QOI_DIFF_8 0x80 // 10xxxxxx
#define QOI_DIFF_16 0xc0 // 110xxxxx #define QOI_DIFF_16 0xc0 // 1100xxxx
#define QOI_GDIFF_16 0xd0 // 1101xxxx
#define QOI_DIFF_24 0xe0 // 1110xxxx #define QOI_DIFF_24 0xe0 // 1110xxxx
#define QOI_COLOR 0xf0 // 1111xxxx #define QOI_COLOR 0xf0 // 1111xxxx
#define QOI_MASK_2 0xc0 // 11000000 #define QOI_MASK_2 0xc0 // 11000000
#define QOI_MASK_3 0xe0 // 11100000
#define QOI_MASK_4 0xf0 // 11110000 #define QOI_MASK_4 0xf0 // 11110000
#define QOI_COLOR_HASH(C) (C.rgba.r ^ C.rgba.g ^ C.rgba.b ^ C.rgba.a) #define QOI_COLOR_HASH(C) (C.rgba.r ^ C.rgba.g ^ C.rgba.b ^ C.rgba.a)
@ -403,17 +411,9 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
if ( if (
run > 0 && run > 0 &&
(run == 0x2020 || px.v != px_prev.v || px_pos == px_end) (run == 64 || px.v != px_prev.v || px_pos == px_end)
) { ) {
if (run < 33) { bytes[p++] = QOI_RUN | (run - 1);
run -= 1;
bytes[p++] = QOI_RUN_8 | run;
}
else {
run -= 33;
bytes[p++] = QOI_RUN_16 | run >> 8;
bytes[p++] = run;
}
run = 0; run = 0;
} }
@ -426,17 +426,14 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
else { else {
index[index_pos] = px; index[index_pos] = px;
int vr = px.rgba.r - px_prev.rgba.r; char vr = px.rgba.r - px_prev.rgba.r;
int vg = px.rgba.g - px_prev.rgba.g; char vg = px.rgba.g - px_prev.rgba.g;
int vb = px.rgba.b - px_prev.rgba.b; char vb = px.rgba.b - px_prev.rgba.b;
int va = px.rgba.a - px_prev.rgba.a; char va = px.rgba.a - px_prev.rgba.a;
char vg_r = vr - vg;
char vg_b = vb - vg;
if (
vr > -17 && vr < 16 &&
vg > -17 && vg < 16 &&
vb > -17 && vb < 16 &&
va > -17 && va < 16
) {
if ( if (
va == 0 && va == 0 &&
vr > -3 && vr < 2 && vr > -3 && vr < 2 &&
@ -447,19 +444,32 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
} }
else if ( else if (
va == 0 && va == 0 &&
vr > -17 && vr < 16 && vr > -9 && vr < 8 &&
vg > -9 && vg < 8 && vg > -9 && vg < 8 &&
vb > -9 && vb < 8 vb > -9 && vb < 8
) { ) {
bytes[p++] = QOI_DIFF_16 | (vr + 16); bytes[p++] = QOI_DIFF_16 | (vr + 8);
bytes[p++] = (vg + 8) << 4 | (vb + 8); bytes[p++] = (vg + 8) << 4 | (vb + 8);
} }
else { else if (
va == 0 &&
vg_r > -5 && vg_r < 4 &&
vg > -33 && vg < 32 &&
vg_b > -5 && vg_b < 4
) {
bytes[p++] = QOI_GDIFF_16 | (vg_r + 4) << 1 | (vg + 32) >> 5;
bytes[p++] = (vg + 32) << 3 | (vg_b + 4);
}
else if (
vr > -17 && vr < 16 &&
vg > -17 && vg < 16 &&
vb > -17 && vb < 16 &&
va > -17 && va < 16
) {
bytes[p++] = QOI_DIFF_24 | (vr + 16) >> 1; bytes[p++] = QOI_DIFF_24 | (vr + 16) >> 1;
bytes[p++] = (vr + 16) << 7 | (vg + 16) << 2 | (vb + 16) >> 3; bytes[p++] = (vr + 16) << 7 | (vg + 16) << 2 | (vb + 16) >> 3;
bytes[p++] = (vb + 16) << 5 | (va + 16); bytes[p++] = (vb + 16) << 5 | (va + 16);
} }
}
else { else {
bytes[p++] = QOI_COLOR | (vr ? 8 : 0) | (vg ? 4 : 0) | (vb ? 2 : 0) | (va ? 1 : 0); bytes[p++] = QOI_COLOR | (vr ? 8 : 0) | (vg ? 4 : 0) | (vb ? 2 : 0) | (va ? 1 : 0);
if (vr) { bytes[p++] = px.rgba.r; } if (vr) { bytes[p++] = px.rgba.r; }
@ -531,24 +541,27 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
if ((b1 & QOI_MASK_2) == QOI_INDEX) { if ((b1 & QOI_MASK_2) == QOI_INDEX) {
px = index[b1 ^ QOI_INDEX]; px = index[b1 ^ QOI_INDEX];
} }
else if ((b1 & QOI_MASK_3) == QOI_RUN_8) { else if ((b1 & QOI_MASK_2) == QOI_RUN) {
run = (b1 & 0x1f); run = (b1 & 0x3f);
}
else if ((b1 & QOI_MASK_3) == QOI_RUN_16) {
int b2 = bytes[p++];
run = (((b1 & 0x1f) << 8) | (b2)) + 32;
} }
else if ((b1 & QOI_MASK_2) == QOI_DIFF_8) { else if ((b1 & QOI_MASK_2) == QOI_DIFF_8) {
px.rgba.r += ((b1 >> 4) & 0x03) - 2; px.rgba.r += ((b1 >> 4) & 0x03) - 2;
px.rgba.g += ((b1 >> 2) & 0x03) - 2; px.rgba.g += ((b1 >> 2) & 0x03) - 2;
px.rgba.b += ( b1 & 0x03) - 2; px.rgba.b += ( b1 & 0x03) - 2;
} }
else if ((b1 & QOI_MASK_3) == QOI_DIFF_16) { else if ((b1 & QOI_MASK_4) == QOI_DIFF_16) {
int b2 = bytes[p++]; int b2 = bytes[p++];
px.rgba.r += (b1 & 0x1f) - 16; px.rgba.r += (b1 & 0x0f) - 8;
px.rgba.g += (b2 >> 4) - 8; px.rgba.g += (b2 >> 4) - 8;
px.rgba.b += (b2 & 0x0f) - 8; px.rgba.b += (b2 & 0x0f) - 8;
} }
else if ((b1 & QOI_MASK_4) == QOI_GDIFF_16) {
int b2 = bytes[p++];
int vg = ((b1 & 0x01) << 5 | (b2 & 0xf8) >> 3) - 32;
px.rgba.r += vg - 4 + ((b1 & 0x0e) >> 1);
px.rgba.g += vg;
px.rgba.b += vg - 4 + (b2 & 0x07);
}
else if ((b1 & QOI_MASK_4) == QOI_DIFF_24) { else if ((b1 & QOI_MASK_4) == QOI_DIFF_24) {
int b2 = bytes[p++]; int b2 = bytes[p++];
int b3 = bytes[p++]; int b3 = bytes[p++];