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/* Pixle image / PAL conversion
*
* (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
* All Rights Reserved
*
* This program 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 3 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <math.h>
#include <stdlib.h>
#include "../common/sample.h"
#include "image.h"
/* render image line starting with x and end with LINE_LENGTH
*
* sample: pointer to samples, starting at x = 0
* samplerate: is the sample rate in hertz
* x: at what x to start rendering
* line: line no. to render
*/
int image_gen_line(sample_t *sample, double x, double samplerate, sample_t *color_u, sample_t *color_v, int v_polarity, double line_start, double line_end, unsigned short *img, int width)
{
double img_x = 0;
double step = 1.0 / samplerate;
double img_step = (double)width / (samplerate * (line_end - line_start));
int i = 0;
double R, G, B, Y, U, V;
/* skip x to line_start */
while (x < line_start && x < line_end) {
i++;
x += step;
}
if (x >= line_end)
return i;
/* draw pixle into image */
while (x < line_end) {
R = (double)(img[(int)img_x*3+0]) / 65535.0;
G = (double)(img[(int)img_x*3+1]) / 65535.0;
B = (double)(img[(int)img_x*3+2]) / 65535.0;
Y = 0.299 * R + 0.587 * G + 0.114 * B;
U = 0.492 * (B - Y);
V = 0.877 * (R - Y);
sample[i] = Y;
color_u[i] = U;
color_v[i] = V * (double)v_polarity;
i++;
x += step;
img_x += img_step;
if ((int)img_x == width)
break;
}
return i;
}
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