From 94dccc74e544e1414b397b18e32f8bc2b21f0b7c Mon Sep 17 00:00:00 2001 From: Xerbo Date: Fri, 17 Jan 2020 13:43:20 +0000 Subject: [PATCH] Add realtime decoding Change calibration to better suit constant gain Add -Wextra to Makefile Add link to model of the PLL Max number of rows for the image is now increasible --- Makefile | 2 +- README.md | 25 ++++++++- dsp.c | 3 +- image.c | 136 +++++++++++++++++--------------------------- main.c | 30 +++++++--- offsets.h | 1 + pngio.c | 164 ++++++++++++++++++++++++++++++++++++------------------ 7 files changed, 207 insertions(+), 154 deletions(-) diff --git a/Makefile b/Makefile index 09f8f29..70cad04 100644 --- a/Makefile +++ b/Makefile @@ -1,7 +1,7 @@ CC = gcc BIN = /usr/bin INCLUDES = -I. -CFLAGS = -O3 -DNDEBUG -Wall $(INCLUDES) +CFLAGS = -O3 -DNDEBUG -Wall -Wextra $(INCLUDES) OBJS = main.o image.o dsp.o filter.o reg.o fcolor.o pngio.o median.o color.o aptdec: $(OBJS) diff --git a/README.md b/README.md index 82a1d2d..553cca5 100644 --- a/README.md +++ b/README.md @@ -51,7 +51,7 @@ To uninstall ## Options ``` --i [r|a|b|c|t|l] +-i [r|a|b|c|t|m] Output image type Raw (r), Channel A (a), Channel B (b), False Color (c), Temperature (t) or MCIR (m) Default: "ab" @@ -65,7 +65,7 @@ Satellite number For temperature calibration Default: "19" --e [t|h] +-e [t|h|d|p] Effects Histogram equalise (h), Crop Telemetry (t), Denoise (d) or Precipitation (p) Defaults: off @@ -76,6 +76,9 @@ Map file generated by wxmap -c Use configuration file for false color generation Default: Internal defaults + +-r +Realtime decode. When decoding in realtime it is highly recommended to choose a plain raw image. ``` ## Output @@ -97,12 +100,28 @@ Currently there are 4 available effects: - `d` for a median denoise filter - `p` for a precipitation overlay -## Example +## Examples `aptdec -d images -i ab *.wav` This will process all `.wav` files in the current directory, generate calibrated channel A and B images and put them in the `images` directory. +`aptdec -e dh -i b audio.wav` + +Decode `audio.wav` with denoise and histogram equalisation and save it into the current directory. + +## Realtime decoding + +As of recently a realtime output was added allowing realtime decoding of images. + +``` +mkfifo /tmp/aptaudio +aptdec /tmp/aptaudio +sox -t pulseaudio alsa_output.pci-0000_00_1b.0.analog-stereo.monitor -c 1 -t wav /tmp/aptaudio +``` + +Perform a realtime decode with the audio being played out of`alsa_output.pci-0000_00_1b.0.analog`. + ## Further reading [https://noaasis.noaa.gov/NOAASIS/pubs/Users_Guide-Building_Receive_Stations_March_2009.pdf](https://noaasis.noaa.gov/NOAASIS/pubs/Users_Guide-Building_Receive_Stations_March_2009.pdf) diff --git a/dsp.c b/dsp.c index 068fcf0..88081f6 100755 --- a/dsp.c +++ b/dsp.c @@ -97,9 +97,8 @@ static inline double Phase(double I, double Q) { } /* Phase locked loop - * https://en.wikipedia.org/wiki/Phase-locked_loop * https://arachnoid.com/phase_locked_loop/ - * https://simple.wikipedia.org/wiki/Phase-locked_loop + * Model of this filter here https://www.desmos.com/calculator/m0uadgkoee */ static double pll(double I, double Q) { // PLL coefficient diff --git a/image.c b/image.c index 3e38ffd..3437675 100644 --- a/image.c +++ b/image.c @@ -32,7 +32,7 @@ typedef struct { } rgparam_t; typedef struct { - float *prow[3000]; // Row buffers + float *prow[MAX_HEIGHT]; // Row buffers int nrow; // Number of rows int chA, chB; // ID of each channel char name[256]; // Stripped filename @@ -44,6 +44,7 @@ typedef struct { int satnum; // The satellite number char *map; // Path to a map file char *path; // Output directory + int realtime; } options_t; extern void polyreg(const int m, const int n, const double x[], const double y[], double c[]); @@ -70,7 +71,6 @@ static double rgcal(float x, rgparam_t *rgpr) { static double tele[16]; static double Cs; -static int nbtele; void histogramEqualise(float **prow, int nrow, int offset, int width){ // Plot histogram @@ -101,77 +101,59 @@ void histogramEqualise(float **prow, int nrow, int offset, int width){ } // Brightness calibrate, including telemetry -void calibrateBrightness(float **prow, int nrow, int offset, int width, int telestart, rgparam_t regr[30]){ +void calibrateImage(float **prow, int nrow, int offset, int width, rgparam_t regr){ offset -= SYNC_WIDTH+SPC_WIDTH; for (int n = 0; n < nrow; n++) { float *pixelv = prow[n]; for (int i = 0; i < width+SYNC_WIDTH+SPC_WIDTH+TELE_WIDTH; i++) { - float pv = pixelv[i + offset]; + float pv = rgcal(pixelv[i + offset], ®r); - // Blend between the calculated regression curves - /* FIXME: this can actually make the image look *worse* - * if the signal has a constant input gain. - */ - /*int k, kof; - k = (n - telestart) / FRAME_LEN; - if (k >= nbtele) - k = nbtele - 1; - kof = (n - telestart) % FRAME_LEN; - - if (kof < 64) { - if (k < 1) {*/ - pv = rgcal(pv, &(regr[4])); - /*} else { - pv = rgcal(pv, &(regr[k])) * (64 + kof) / FRAME_LEN + - rgcal(pv, &(regr[k - 1])) * (64 - kof) / FRAME_LEN; - } - } else { - if ((k + 1) >= nbtele) { - pv = rgcal(pv, &(regr[k])); - } else { - pv = rgcal(pv, &(regr[k])) * (192 - kof) / FRAME_LEN + - rgcal(pv, &(regr[k + 1])) * (kof - 64) / FRAME_LEN; - } - } -*/ - pv = CLIP(pv, 0, 255); - pixelv[i + offset] = pv; + pixelv[i + offset] = CLIP(pv, 0, 255); } } } +double teleNoise(double wedges[16]){ + int pattern[9] = { 31, 63, 95, 127, 159, 191, 223, 255, 0 }; + double noise = 0; + for(int i = 0; i < 9; i++) + noise += fabs(wedges[i] - (double)pattern[i]); + + return noise; +} + // Get telemetry data for thermal calibration/equalization int calibrate(float **prow, int nrow, int offset, int width) { - double teleline[3000] = { 0.0 }; + double teleline[MAX_HEIGHT] = { 0.0 }; double wedge[16]; rgparam_t regr[30]; - int n, k; - int mtelestart = 0, telestart; - int channel = -1; + int telestart, mtelestart = 0; + int channel = -1; + + // The minimum rows required to decode a full frame + if (nrow < 192) { + fprintf(stderr, ERR_TELE_ROW); + return 0; + } // Calculate average of a row of telemetry - for (n = 0; n < nrow; n++) { + for (int n = 0; n < nrow; n++) { float *pixelv = prow[n]; // Average the center 40px - for (int i = 3; i < 43; i++) teleline[n] += pixelv[i + offset + width]; + for (int i = 3; i < 43; i++) + teleline[n] += pixelv[i + offset + width]; teleline[n] /= 40.0; } - // The minimum rows required to decode a full frame - if (nrow < 192) { - fprintf(stderr, ERR_TELE_ROW); - return(0); - } - - /* Wedge 7 is white and 8 is black, which will have the largest + /* Wedge 7 is white and 8 is black, this will have the largest * difference in brightness, this will always be in the center of * the frame and can thus be used to find the start of the frame */ double max = 0.0; - for (n = nrow / 3 - 64; n < 2 * nrow / 3 - 64; n++) { + for (int n = nrow / 3 - 64; n < 2 * nrow / 3 - 64; n++) { float df; // (sum 4px below) / (sum 4px above) @@ -194,68 +176,50 @@ int calibrate(float **prow, int nrow, int offset, int width) { return(0); } - // For each frame - for (n = telestart, k = 0; n < nrow - FRAME_LEN; n += FRAME_LEN, k++) { - float *pixelv = prow[n]; - int j; + // Find the least noisy frame + double minNoise = -1; + int bestFrame = telestart; + for (int n = telestart, k = 0; n < nrow - FRAME_LEN; n += FRAME_LEN, k++) { + // Turn pixels into wedge values + for (int j = 0; j < 16; j++) { + wedge[j] = 0.0; - // Turn each wedge into a value - for (j = 0; j < 16; j++) { // Average the middle 6px - wedge[j] = 0.0; - for (int i = 1; i < 7; i++) wedge[j] += teleline[(j * 8) + n + i]; + for (int i = 1; i < 7; i++) + wedge[j] += teleline[(j * 8) + i + n]; wedge[j] /= 6; } - // Compute regression on the wedges - rgcomp(wedge, &(regr[k])); + double noise = teleNoise(wedge); + if(noise < minNoise || minNoise == -1){ + minNoise = noise; + bestFrame = k; - // Read the telemetry values from the middle of the image - if (k == nrow / (2*FRAME_LEN)) { - int l; - - // Equalise - for (j = 0; j < 16; j++) tele[j] = rgcal(wedge[j], &(regr[k])); + // Compute & apply regression on the wedges + rgcomp(wedge, ®r[k]); + for (int j = 0; j < 16; j++) + tele[j] = rgcal(wedge[j], ®r[k]); /* Compare the channel ID wedge to the reference * wedges, the wedge with the closest match will * be the channel ID */ float min = -1; - for (j = 0; j < 6; j++) { - float df; - - df = tele[15] - tele[j]; + for (int j = 0; j < 6; j++) { + float df = tele[15] - tele[j]; df *= df; + if (df < min || min == -1) { channel = j; min = df; } } - - // Cs computation, still have no idea what this does - int i; - for (Cs = 0.0, i = 0, j = n; j < n + FRAME_LEN; j++) { - double csline; - - for (csline = 0.0, l = 3; l < 43; l++) - csline += pixelv[l + offset - SPC_WIDTH]; - - csline /= 40.0; - if (csline > 50.0) { - Cs += csline; - i++; - } - } - Cs /= i; - Cs = rgcal(Cs, &(regr[k])); } } - nbtele = k; - calibrateBrightness(prow, nrow, offset, width, telestart, regr); + calibrateImage(prow, nrow, offset, width, regr[bestFrame]); - return(channel + 1); + return channel + 1; } // --- Temperature Calibration --- // diff --git a/main.c b/main.c index c6089b3..293a1c2 100644 --- a/main.c +++ b/main.c @@ -38,10 +38,11 @@ typedef struct { int satnum; // The satellite number char *map; // Path to a map file char *path; // Output directory + int realtime; } options_t; typedef struct { - float *prow[3000]; // Row buffers + float *prow[MAX_HEIGHT]; // Row buffers int nrow; // Number of rows int chA, chB; // ID of each channel char name[256]; // Stripped filename @@ -55,6 +56,9 @@ extern int init_dsp(double F); extern int readfcconf(char *file); extern int readRawImage(char *filename, float **prow, int *nrow); extern int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, char *chid, char *palette); +extern void closeWriter(); +extern void pushRow(float *row, int width); +extern int initWriter(options_t *opts, image_t *img, int width, int height, char *desc, char *chid); // Image functions extern int calibrate(float **prow, int nrow, int offset, int width); @@ -90,11 +94,11 @@ int main(int argc, char **argv) { usage(); } - options_t opts = { "r", "", 19, "", "." }; + options_t opts = { "r", "", 19, "", ".", 0 }; // Parse arguments int opt; - while ((opt = getopt(argc, argv, "c:m:d:i:s:e:")) != EOF) { + while ((opt = getopt(argc, argv, "c:m:d:i:s:e:r")) != EOF) { switch (opt) { case 'd': opts.path = optarg; @@ -118,6 +122,9 @@ int main(int argc, char **argv) { case 'e': opts.effects = optarg; break; + case 'r': + opts.realtime = 1; + break; default: usage(); } @@ -153,6 +160,8 @@ static int processAudio(char *filename, options_t *opts){ strcpy(path, dirname(path)); sscanf(basename(filename), "%[^.].%s", img.name, extension); + if(opts->realtime) initWriter(opts, &img, IMG_WIDTH, MAX_HEIGHT, "Unprocessed realtime image", "r"); + if(strcmp(extension, "png") == 0){ // Read PNG into image buffer printf("Reading %s", filename); @@ -166,7 +175,7 @@ static int processAudio(char *filename, options_t *opts){ exit(EPERM); // Build image - for (img.nrow = 0; img.nrow < 3000; img.nrow++) { + for (img.nrow = 0; img.nrow < MAX_HEIGHT; img.nrow++) { // Allocate memory for this row img.prow[img.nrow] = (float *) malloc(sizeof(float) * 2150); @@ -174,6 +183,8 @@ static int processAudio(char *filename, options_t *opts){ if (getpixelrow(img.prow[img.nrow], img.nrow, &zenith) == 0) break; + if(opts->realtime) pushRow(img.prow[img.nrow], IMG_WIDTH); + fprintf(stderr, "Row: %d\r", img.nrow); fflush(stderr); } @@ -182,6 +193,8 @@ static int processAudio(char *filename, options_t *opts){ sf_close(audioFile); } + if(opts->realtime) closeWriter(); + printf("\nTotal rows: %d\n", img.nrow); // Fallback for detecting the zenith @@ -248,7 +261,7 @@ static int processAudio(char *filename, options_t *opts){ // Channel B if (CONTAINS(opts->type, 'b')) { sprintf(desc, "%s (%s)", ch.id[img.chB], ch.name[img.chB]); - ImageOut(opts, &img, CHB_OFFSET, CH_WIDTH, desc, ch.id[img.chA], NULL); + ImageOut(opts, &img, CHB_OFFSET, CH_WIDTH, desc, ch.id[img.chB], NULL); } // Distribution image @@ -292,7 +305,7 @@ static int initsnd(char *filename) { // Read samples from the wave file int getsample(float *sample, int nb) { - return sf_read_float(audioFile, sample, nb); + return sf_read_float(audioFile, sample, nb); } static void usage(void) { @@ -304,7 +317,7 @@ static void usage(void) { " h: Histogram equalise\n" " d: Denoise\n" " p: Precipitation\n" - " -i [r|a|b|c|t] Output image\n" + " -i [r|a|b|c|t|m] Output image\n" " r: Raw\n" " a: Channel A\n" " b: Channel B\n" @@ -314,7 +327,8 @@ static void usage(void) { " -d Image destination directory.\n" " -s [15-19] Satellite number\n" " -c False color config file\n" - " -m Map file\n"); + " -m Map file\n" + " -r Realtime decode"); exit(EINVAL); } \ No newline at end of file diff --git a/offsets.h b/offsets.h index 56671d3..c646bb5 100644 --- a/offsets.h +++ b/offsets.h @@ -27,6 +27,7 @@ #define CHA_OFFSET (SYNC_WIDTH+SPC_WIDTH) #define CHB_OFFSET (SYNC_WIDTH+SPC_WIDTH+CH_WIDTH+TELE_WIDTH+SYNC_WIDTH+SPC_WIDTH) #define TOTAL_TELE (SYNC_WIDTH+SPC_WIDTH+TELE_WIDTH+SYNC_WIDTH+SPC_WIDTH+TELE_WIDTH) +#define MAX_HEIGHT 3000 #define CLIP(val, bottom, top) (val > top ? top : (val > bottom ? val : bottom)) #define CONTAINS(str, char) (strchr(str, (int) char) != NULL) diff --git a/pngio.c b/pngio.c index c3010f5..17c34bd 100644 --- a/pngio.c +++ b/pngio.c @@ -30,10 +30,27 @@ typedef struct { float r, g, b; } rgb_t; +typedef struct { + float *prow[MAX_HEIGHT]; // Row buffers + int nrow; // Number of rows + int chA, chB; // ID of each channel + char name[256]; // Stripped filename +} image_t; + +typedef struct { + char *type; // Output image type + char *effects; + int satnum; // The satellite number + char *map; // Path to a map file + char *path; // Output directory + int realtime; +} options_t; + extern int zenith; extern char PrecipPalette[256*3]; extern rgb_t applyPalette(char *palette, int val); extern rgb_t RGBcomposite(rgb_t top, float top_a, rgb_t bottom, float bottom_a); +extern rgb_t falsecolor(float vis, float temp); int mapOverlay(char *filename, rgb_t **crow, int nrow, int zenith, int MCIR) { FILE *fp = fopen(filename, "rb"); @@ -118,7 +135,6 @@ int mapOverlay(char *filename, rgb_t **crow, int nrow, int zenith, int MCIR) { // Map overlay on channel A crow[y][cha] = RGBcomposite(map, alpha, crow[y][cha], 1); - // Map overlay on channel B if(!MCIR) crow[y][chb] = RGBcomposite(map, alpha, crow[y][chb], 1); @@ -188,33 +204,20 @@ int readRawImage(char *filename, float **prow, int *nrow) { return 1; } -typedef struct { - float *prow[3000]; // Row buffers - int nrow; // Number of rows - int chA, chB; // ID of each channel - char name[256]; // Stripped filename -} image_t; +png_text text_ptr[] = { + {PNG_TEXT_COMPRESSION_NONE, "Software", VERSION}, + {PNG_TEXT_COMPRESSION_NONE, "Channel", "Unknown", 7}, + {PNG_TEXT_COMPRESSION_NONE, "Description", "NOAA satellite image", 20} +}; -typedef struct { - char *type; // Output image type - char *effects; - int satnum; // The satellite number - char *map; // Path to a map file - char *path; // Output directory -} options_t; - -//int ImageOut(char *filename, char *chid, float **prow, int nrow, int width, int offset, char *palette, char *effects, char *mapFile) { int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, char *chid, char *palette){ char outName[384]; sprintf(outName, "%s/%s-%s.png", opts->path, img->name, chid); - FILE *pngfile; + text_ptr[1].text = desc; + text_ptr[1].text_length = sizeof(desc); - png_text text_ptr[] = { - {PNG_TEXT_COMPRESSION_NONE, "Software", VERSION}, - {PNG_TEXT_COMPRESSION_NONE, "Channel", desc, sizeof(desc)}, - {PNG_TEXT_COMPRESSION_NONE, "Description", "NOAA satellite image", 20} - }; + FILE *pngfile; // Reduce the width of the image to componsate for the missing telemetry int fcimage = strcmp(desc, "False Color") == 0; @@ -229,13 +232,13 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c if (!png_ptr) { png_destroy_write_struct(&png_ptr, (png_infopp) NULL); fprintf(stderr, ERR_PNG_WRITE); - return(0); + return 0; } png_infop info_ptr = png_create_info_struct(png_ptr); if (!info_ptr) { png_destroy_write_struct(&png_ptr, (png_infopp) NULL); fprintf(stderr, ERR_PNG_INFO); - return(0); + return 0; } int greyscale = 0; @@ -254,35 +257,34 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c } png_set_text(png_ptr, info_ptr, text_ptr, 3); - - // Channel = 25cm wide png_set_pHYs(png_ptr, info_ptr, 3636, 3636, PNG_RESOLUTION_METER); // Init I/O pngfile = fopen(outName, "wb"); if (!pngfile) { fprintf(stderr, ERR_FILE_WRITE, outName); - return(1); + return 1; } png_init_io(png_ptr, pngfile); png_write_info(png_ptr, info_ptr); // Move prow into crow, crow ~ color rows rgb_t *crow[img->nrow]; - for(int y = 0; y < img->nrow; y++){ - crow[y] = (rgb_t *) malloc(sizeof(rgb_t) * IMG_WIDTH); + if(!greyscale){ + for(int y = 0; y < img->nrow; y++){ + crow[y] = (rgb_t *) malloc(sizeof(rgb_t) * IMG_WIDTH); - for(int x = 0; x < IMG_WIDTH; x++){ - if(palette == NULL){ - crow[y][x].r = crow[y][x].g = crow[y][x].b = CLIP(img->prow[y][x], 0, 255); - }else{ - crow[y][x] = applyPalette(palette, img->prow[y][x]); + for(int x = 0; x < IMG_WIDTH; x++){ + if(palette == NULL) + crow[y][x].r = crow[y][x].g = crow[y][x].b = CLIP(img->prow[y][x], 0, 255); + else + crow[y][x] = applyPalette(palette, img->prow[y][x]); } } } // Precipitation - // TODO: use temperature calibration for accuracy + // TODO: use temperature calibration if(CONTAINS(opts->effects, 'p')){ for(int y = 0; y < img->nrow; y++){ for(int x = 0; x < CH_WIDTH; x++){ @@ -292,6 +294,7 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c } } + // Map stuff if(opts->map != NULL && opts->map[0] != '\0'){ if(mapOverlay(opts->map, crow, img->nrow, zenith, strcmp(chid, "MCIR") == 0) == 0){ fprintf(stderr, "Skipping MCIR generation; see above.\n"); @@ -304,11 +307,10 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c printf("Writing %s", outName); - extern rgb_t falsecolor(float vis, float temp); - // Build image for (int y = 0; y < img->nrow; y++) { png_color pix[width]; + png_byte gpix[width]; int skip = 0; for (int x = 0; x < width; x++) { @@ -320,31 +322,24 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c case CH_WIDTH: skip += TELE_WIDTH + SYNC_WIDTH + SPC_WIDTH; break; - case CH_WIDTH*2: - skip += TELE_WIDTH; - break; } } + if(greyscale){ - // Horrific but works - if(x % 3 == 0){ - pix[x/3].red = img->prow[y][x + skip + offset ]; - pix[x/3].green = img->prow[y][x + skip + offset+1]; - pix[x/3].blue = img->prow[y][x + skip + offset+2]; - } + gpix[x] = img->prow[y][x + skip + offset]; }else if(fcimage){ rgb_t pixel = falsecolor(img->prow[y][x + CHA_OFFSET], img->prow[y][x + CHB_OFFSET]); - pix[x].red = pixel.r; - pix[x].green = pixel.g; - pix[x].blue = pixel.b; + pix[x] = (png_color){pixel.r, pixel.g, pixel.b}; }else{ - pix[x].red = crow[y][x + skip + offset].r; - pix[x].green = crow[y][x + skip + offset].g; - pix[x].blue = crow[y][x + skip + offset].b; + pix[x] = (png_color){crow[y][x + skip + offset].r, crow[y][x + skip + offset].g, crow[y][x + skip + offset].b}; } } - png_write_row(png_ptr, (png_bytep) pix); + if(greyscale){ + png_write_row(png_ptr, (png_bytep) gpix); + }else{ + png_write_row(png_ptr, (png_bytep) pix); + } } // Tidy up @@ -353,6 +348,67 @@ int ImageOut(options_t *opts, image_t *img, int offset, int width, char *desc, c printf("\nDone\n"); png_destroy_write_struct(&png_ptr, &info_ptr); - return(1); + return 1; +} + +// TODO: remove these from the global scope +png_structp rt_png_ptr; +png_infop rt_info_ptr; +FILE *rt_pngfile; + +int initWriter(options_t *opts, image_t *img, int width, int height, char *desc, char *chid){ + char outName[384]; + sprintf(outName, "%s/%s-%s.png", opts->path, img->name, chid); + + text_ptr[1].text = desc; + text_ptr[1].text_length = sizeof(desc); + + // Create writer + rt_png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); + if (!rt_png_ptr) { + png_destroy_write_struct(&rt_png_ptr, (png_infopp) NULL); + fprintf(stderr, ERR_PNG_WRITE); + return 0; + } + rt_info_ptr = png_create_info_struct(rt_png_ptr); + if (!rt_info_ptr) { + png_destroy_write_struct(&rt_png_ptr, (png_infopp) NULL); + fprintf(stderr, ERR_PNG_INFO); + return 0; + } + + // Greyscale image + png_set_IHDR(rt_png_ptr, rt_info_ptr, width, height, + 8, PNG_COLOR_TYPE_GRAY, PNG_INTERLACE_NONE, + PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); + + png_set_text(rt_png_ptr, rt_info_ptr, text_ptr, 3); + + // Channel = 25cm wide + png_set_pHYs(rt_png_ptr, rt_info_ptr, 3636, 3636, PNG_RESOLUTION_METER); + + // Init I/O + rt_pngfile = fopen(outName, "wb"); + if (!rt_pngfile) { + fprintf(stderr, ERR_FILE_WRITE, outName); + return 0; + } + png_init_io(rt_png_ptr, rt_pngfile); + png_write_info(rt_png_ptr, rt_info_ptr); + + return 1; +} + +void pushRow(float *row, int width){ + png_byte pix[width]; + for(int i = 0; i < width; i++) + pix[i] = row[i]; + + png_write_row(rt_png_ptr, (png_bytep) pix); } +void closeWriter(){ + png_write_end(rt_png_ptr, rt_info_ptr); + fclose(rt_pngfile); + png_destroy_write_struct(&rt_png_ptr, &rt_info_ptr); +} \ No newline at end of file