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libretro-atari800/atari800/src/colours_ntsc.c
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/*
* colours_ntsc.c - Atari NTSC colour palette generation and adjustment
*
* Copyright (C) 2009-2010 Atari800 development team (see DOC/CREDITS)
*
* This file is part of the Atari800 emulator project which emulates
* the Atari 400, 800, 800XL, 130XE, and 5200 8-bit computers.
*
* Atari800 is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Atari800 is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Atari800; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "colours_ntsc.h"
#include "config.h"
#include "atari.h" /* for TRUE/FALSE */
#include "colours.h"
#include "log.h"
#include "util.h"
Colours_setup_t COLOURS_NTSC_setup;
/* NTSC-specific default setup. */
static struct {
double color_delay;
} const default_setup = {
26.8, /* color delay, chosen to match color names given in GTIA.PDF */
};
COLOURS_EXTERNAL_t COLOURS_NTSC_external = { "", FALSE, FALSE };
/* NTSC colorburst angle in YIQ colorspace. Colorburst is at
* 180 degrees in YUV - that is, a gold color. In YIQ, gold is at
* different angle. However, YIQ is actually YUV turned
* 33 degrees. So by looking at screenshots at Wikipedia we can
* conclude that the colorburst angle is 270+33 in YIQ.
* (See http://en.wikipedia.org/wiki/YUV and
* http://en.wikipedia.org/wiki/YIQ) */
static const double colorburst_angle = (303.0f) * M_PI / 180.0f;
/* In COLOURS_NTSC colours are generated in 2 stages:
1. Generate Y, I and Q values for all 256 colours and store in an
intermediate yiq_table;
2. Convert YIQ to RGB.
Splitting the process to 2 stages is necessary to allow the NTSC_FILTER
module to use the same palette generation routines. Without such
requirement, NTSC palette generation would be performed in one stage,
similarly to the COLOURS_PAL module. */
/* Creates YIQ_TABLE from external palette. START_ANGLE and START_SATURATIION
are provided as parameters, because NTSC_FILTER needs to set these values
according to its internal setup (burst_phase etc.).
External palette is not adjusted if COLOURS_NTSC_external.adjust is false. */
static void UpdateYIQTableFromExternal(double yiq_table[768], double start_angle, const double start_saturation)
{
unsigned char *ext_ptr = COLOURS_NTSC_external.palette;
int n;
start_angle -= colorburst_angle;
for (n = 0; n < 256; n ++) {
/* Convert RGB values from external palette to YIQ. */
double r = (double)*ext_ptr++ / 255.0;
double g = (double)*ext_ptr++ / 255.0;
double b = (double)*ext_ptr++ / 255.0;
double y = 0.299 * r + 0.587 * g + 0.114 * b;
double i = 0.595716 * r - 0.274453 * g - 0.321263 * b;
double q = 0.211456 * r - 0.522591 * g + 0.311135 * b;
double s = sin(start_angle);
double c = cos(start_angle);
double tmp_i = i;
i = tmp_i * c - q * s;
q = tmp_i * s + q * c;
/* Optionally adjust external palette. */
if (COLOURS_NTSC_external.adjust) {
y *= COLOURS_NTSC_setup.contrast * 0.5 + 1;
y += COLOURS_NTSC_setup.brightness * 0.5;
if (y > 1.0)
y = 1.0;
else if (y < 0.0)
y = 0.0;
i *= start_saturation + 1;
q *= start_saturation + 1;
}
*yiq_table++ = y;
*yiq_table++ = i;
*yiq_table++ = q;
}
}
/* Generates NTSC palette into YIQ_TABLE. START_ANGLE and START_SATURATIION
are provided as parameters, because NTSC_FILTER needs to set these values
according to its internal setup (burst_phase etc.) */
static void UpdateYIQTableFromGenerated(double yiq_table[768], const double start_angle, const double start_saturation)
{
/* Difference between two consecutive chrominances, in radians. */
double color_diff = COLOURS_NTSC_setup.color_delay * M_PI / 180.0;
int cr, lm;
double scaled_black_level = (double)COLOURS_NTSC_setup.black_level / 255.0;
double scaled_white_level = (double)COLOURS_NTSC_setup.white_level / 255.0;
/* NTSC luma multipliers from CGIA.PDF */
double luma_mult[16]={
0.6941, 0.7091, 0.7241, 0.7401,
0.7560, 0.7741, 0.7931, 0.8121,
0.8260, 0.8470, 0.8700, 0.8930,
0.9160, 0.9420, 0.9690, 1.0000};
for (cr = 0; cr < 16; cr ++) {
double angle = start_angle + (cr - 1) * color_diff;
double saturation = (cr ? (start_saturation + 1) * 0.175f: 0.0);
double i = cos(angle) * saturation;
double q = sin(angle) * saturation;
for (lm = 0; lm < 16; lm ++) {
/* calculate yiq for color entry */
double y = (luma_mult[lm] - luma_mult[0]) / (luma_mult[15] - luma_mult[0]);
y *= COLOURS_NTSC_setup.contrast * 0.5 + 1;
y += COLOURS_NTSC_setup.brightness * 0.5;
/* Scale the Y signal's range from 0..1 to
* scaled_black_level..scaled_white_level */
y = y * (scaled_white_level - scaled_black_level) + scaled_black_level;
/*
if (y < scaled_black_level)
y = scaled_black_level;
else if (y > scaled_white_level)
y = scaled_white_level;
*/
*yiq_table++ = y;
*yiq_table++ = i;
*yiq_table++ = q;
}
}
}
/* Fills YIQ_TABLE with palette. Depending on the current setup, it is
computed from an internally-generated or external palette. */
static void UpdateYIQTable(double yiq_table[768], double start_angle, const double start_saturation)
{
if (COLOURS_NTSC_external.loaded)
UpdateYIQTableFromExternal(yiq_table, start_angle, start_saturation);
else
UpdateYIQTableFromGenerated(yiq_table, start_angle, start_saturation);
}
void COLOURS_NTSC_GetYIQ(double yiq_table[768], const double start_angle)
{
/* Set the generated palette's saturation to 0.0, because NTSC_FILTER
applies the saturation setting internally. */
UpdateYIQTable(yiq_table, start_angle, 0.0);
}
/* Converts YIQ values from YIQ_TABLE to RGB values. Stores them in
COLOURTABLE. */
static void YIQ2RGB(int colourtable[256], const double yiq_table[768])
{
const double *yiq_ptr = yiq_table;
int n;
for (n = 0; n < 256; n ++) {
double y = *yiq_ptr++;
double i = *yiq_ptr++;
double q = *yiq_ptr++;
double r, g, b;
r = y + 0.9563 * i + 0.6210 * q;
g = y - 0.2721 * i - 0.6474 * q;
b = y - 1.1070 * i + 1.7046 * q;
if (!COLOURS_NTSC_external.loaded || COLOURS_NTSC_external.adjust) {
/* The r, g, b values derived from the YIQ signal are non-linear
(ie. gamma-corrected). We convert them to linear values,
assuming the CRT TV's gamma = COLOURS_NTSC_setup.gamma. */
r = Colours_Gamma2Linear(r, COLOURS_NTSC_setup.gamma);
g = Colours_Gamma2Linear(g, COLOURS_NTSC_setup.gamma);
b = Colours_Gamma2Linear(b, COLOURS_NTSC_setup.gamma);
/* Now we convert the linear values to the sRGB colourspace. */
r = Colours_Linear2sRGB(r);
g = Colours_Linear2sRGB(g);
b = Colours_Linear2sRGB(b);
}
Colours_SetRGB(n, (int) (r * 255), (int) (g * 255), (int) (b * 255), colourtable);
}
}
void COLOURS_NTSC_Update(int colourtable[256])
{
double yiq_table[768];
UpdateYIQTable(yiq_table, colorburst_angle + COLOURS_NTSC_setup.hue * M_PI, COLOURS_NTSC_setup.saturation);
YIQ2RGB(colourtable, yiq_table);
}
void COLOURS_NTSC_RestoreDefaults(void)
{
COLOURS_NTSC_setup.color_delay = default_setup.color_delay;
}
Colours_preset_t COLOURS_NTSC_GetPreset()
{
if (Util_almostequal(COLOURS_NTSC_setup.color_delay, default_setup.color_delay, 0.001))
return COLOURS_PRESET_STANDARD;
return COLOURS_PRESET_CUSTOM;
}
int COLOURS_NTSC_ReadConfig(char *option, char *ptr)
{
if (strcmp(option, "COLOURS_NTSC_SATURATION") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.saturation);
else if (strcmp(option, "COLOURS_NTSC_CONTRAST") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.contrast);
else if (strcmp(option, "COLOURS_NTSC_BRIGHTNESS") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.brightness);
else if (strcmp(option, "COLOURS_NTSC_GAMMA") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.gamma);
else if (strcmp(option, "COLOURS_NTSC_HUE") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.hue);
else if (strcmp(option, "COLOURS_NTSC_GTIA_DELAY") == 0)
return Util_sscandouble(ptr, &COLOURS_NTSC_setup.color_delay);
else if (strcmp(option, "COLOURS_NTSC_EXTERNAL_PALETTE") == 0)
Util_strlcpy(COLOURS_NTSC_external.filename, ptr, sizeof(COLOURS_NTSC_external.filename));
else if (strcmp(option, "COLOURS_NTSC_EXTERNAL_PALETTE_LOADED") == 0)
/* Use the "loaded" flag to indicate that the palette must be loaded later. */
return (COLOURS_NTSC_external.loaded = Util_sscanbool(ptr)) != -1;
else if (strcmp(option, "COLOURS_NTSC_ADJUST_EXTERNAL_PALETTE") == 0)
return (COLOURS_NTSC_external.adjust = Util_sscanbool(ptr)) != -1;
else
return FALSE;
return TRUE;
}
void COLOURS_NTSC_WriteConfig(FILE *fp)
{
fprintf(fp, "COLOURS_NTSC_SATURATION=%g\n", COLOURS_NTSC_setup.saturation);
fprintf(fp, "COLOURS_NTSC_CONTRAST=%g\n", COLOURS_NTSC_setup.contrast);
fprintf(fp, "COLOURS_NTSC_BRIGHTNESS=%g\n", COLOURS_NTSC_setup.brightness);
fprintf(fp, "COLOURS_NTSC_GAMMA=%g\n", COLOURS_NTSC_setup.gamma);
fprintf(fp, "COLOURS_NTSC_HUE=%g\n", COLOURS_NTSC_setup.hue);
fprintf(fp, "COLOURS_NTSC_GTIA_DELAY=%g\n", COLOURS_NTSC_setup.color_delay);
fprintf(fp, "COLOURS_NTSC_EXTERNAL_PALETTE=%s\n", COLOURS_NTSC_external.filename);
fprintf(fp, "COLOURS_NTSC_EXTERNAL_PALETTE_LOADED=%d\n", COLOURS_NTSC_external.loaded);
fprintf(fp, "COLOURS_NTSC_ADJUST_EXTERNAL_PALETTE=%d\n", COLOURS_NTSC_external.adjust);
}
int COLOURS_NTSC_Initialise(int *argc, char *argv[])
{
int i;
int j;
for (i = j = 1; i < *argc; i++) {
int i_a = (i + 1 < *argc); /* is argument available? */
int a_m = FALSE; /* error, argument missing! */
if (strcmp(argv[i], "-ntsc-saturation") == 0) {
if (i_a)
COLOURS_NTSC_setup.saturation = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-ntsc-contrast") == 0) {
if (i_a)
COLOURS_NTSC_setup.contrast = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-ntsc-brightness") == 0) {
if (i_a)
COLOURS_NTSC_setup.brightness = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-ntsc-gamma") == 0) {
if (i_a)
COLOURS_NTSC_setup.gamma = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-ntsc-tint") == 0) {
if (i_a)
COLOURS_NTSC_setup.hue = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-ntsc-colordelay") == 0) {
if (i_a)
COLOURS_NTSC_setup.color_delay = atof(argv[++i]);
else a_m = TRUE;
}
else if (strcmp(argv[i], "-paletten") == 0) {
if (i_a) {
Util_strlcpy(COLOURS_NTSC_external.filename, argv[++i], sizeof(COLOURS_NTSC_external.filename));
/* Use the "loaded" flag to indicate that the palette must be loaded later. */
COLOURS_NTSC_external.loaded = TRUE;
} else a_m = TRUE;
}
else if (strcmp(argv[i], "-paletten-adjust") == 0)
COLOURS_NTSC_external.adjust = TRUE;
else {
if (strcmp(argv[i], "-help") == 0) {
Log_print("\t-ntsc-saturation <num> Set NTSC color saturation");
Log_print("\t-ntsc-contrast <num> Set NTSC contrast");
Log_print("\t-ntsc-brightness <num> Set NTSC brightness");
Log_print("\t-ntsc-gamma <num> Set NTSC color gamma factor");
Log_print("\t-ntsc-tint <num> Set NTSC tint");
Log_print("\t-ntsc-colordelay <num> Set NTSC GTIA color delay");
Log_print("\t-paletten <filename> Load NTSC external palette");
Log_print("\t-paletten-adjust Apply adjustments to NTSC external palette");
}
argv[j++] = argv[i];
}
if (a_m) {
Log_print("Missing argument for '%s'", argv[i]);
return FALSE;
}
}
*argc = j;
/* Try loading an external palette if needed. */
if (COLOURS_NTSC_external.loaded && !COLOURS_EXTERNAL_Read(&COLOURS_NTSC_external))
Log_print("Cannot read NTSC palette from %s", COLOURS_NTSC_external.filename);
return TRUE;
}
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