Author: Martin Guy Date: Thu Jul 26 13:52:35 2012 +0200 Add --gray-scale flag to output levels of gray instead of color map This commit adds a --gray-scale flag which causes andfile-spectrogram to output 256 levels of gray pixels instead of the colored heat map. Values <= spec_floor_db come out ad black, >=0dB as white and the other 254 values are evenly distributed over the rest of the dB scale. diff --git a/src/spectrogram.c b/src/spectrogram.c index cd733cd..5f72fab 100644 --- a/src/spectrogram.c +++ b/src/spectrogram.c @@ -64,7 +64,7 @@ typedef struct { const char *sndfilepath, *pngfilepath, *filename ; int width, height ; - bool border, log_freq ; + bool border, log_freq, gray_scale ; double spec_floor_db ; } RENDER ; @@ -73,7 +73,7 @@ typedef struct } RECT ; static void -get_colour_map_value (float value, double spec_floor_db, unsigned char colour [3]) +get_colour_map_value (float value, double spec_floor_db, unsigned char colour [3], bool gray_scale) { static unsigned char map [][3] = { /* These values were originally calculated for a dynamic range of 180dB. */ { 255, 255, 255 }, /* -0dB */ @@ -105,6 +105,33 @@ get_colour_map_value (float value, double spec_floor_db, unsigned char colour [3 return ; } ; + if (gray_scale) + { /* "value" is a negative value in decibels. + * black (0,0,0) is for <= -180.0, + * white (255,255,255) is for >= 0.0 leaving 254 values + * which should cover the intervening range evenly. + * (value/spec_floor_db) is between 0.0 and 1.0 (not inclusive) + * because both value and spec_floor_db are negative. + * (v/s) * 254.0 is from 0.000001 to 253.9999999 and + * we want 1 to 254, so ceil((v/s) * 254) gives us that, + * converted to 254 to 1 by subtracting from 255. */ + int c; /* The pixel value */ + + if (value <= spec_floor_db) + c = 0; + else + { c = 255 - lrintf (ceil ( (value / spec_floor_db) * 254.0 ) ) ; + + if (c < 1 || c > 254) /* Sanity check */ + { printf ("\nError : gray value is %d\n\n", c) ; + exit (1) ; + } ; + + } ; + colour [0] = colour [1] = colour [2] = c; + return ; + } ; + value = fabs (value * (-180.0 / spec_floor_db) * 0.1) ; indx = lrintf (floor (value)) ; @@ -178,7 +205,7 @@ apply_window (double * data, int datalen) } /* apply_window */ static void -render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float mag2d [MAX_WIDTH][MAX_HEIGHT], double maxval, double left, double top, double width, double height) +render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float mag2d [MAX_WIDTH][MAX_HEIGHT], double maxval, double left, double top, double width, double height, bool gray_scale) { unsigned char colour [3] = { 0, 0, 0 } ; unsigned char *data ; @@ -199,7 +226,7 @@ render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float mag2d mag2d [w][h] = mag2d [w][h] / maxval ; mag2d [w][h] = (mag2d [w][h] < linear_spec_floor) ? spec_floor_db : 20.0 * log10 (mag2d [w][h]) ; - get_colour_map_value (mag2d [w][h], spec_floor_db, colour) ; + get_colour_map_value (mag2d [w][h], spec_floor_db, colour, gray_scale) ; y = height + top - 1 - h ; x = (w + left) * 4 ; @@ -213,7 +240,7 @@ render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float mag2d } /* render_spectrogram */ static void -render_heat_map (cairo_surface_t * surface, double magfloor, const RECT *r) +render_heat_map (cairo_surface_t * surface, double magfloor, const RECT *r, bool gray_scale) { unsigned char colour [3], *data ; int w, h, stride ; @@ -222,7 +249,7 @@ render_heat_map (cairo_surface_t * surface, double magfloor, const RECT *r) data = cairo_image_surface_get_data (surface) ; for (h = 0 ; h < r->height ; h++) - { get_colour_map_value (magfloor * (r->height - h) / (r->height + 1), magfloor, colour) ; + { get_colour_map_value (magfloor * (r->height - h) / (r->height + 1), magfloor, colour, gray_scale) ; for (w = 0 ; w < r->width ; w ++) { int x, y ; @@ -524,15 +551,15 @@ render_to_surface (const RENDER * render, SNDFILE *infile, int samplerate, sf_co heat_rect.width = 12 ; heat_rect.height = height - TOP_BORDER / 2 ; - render_spectrogram (surface, render->spec_floor_db, mag_spec, max_mag, LEFT_BORDER, TOP_BORDER, width, height) ; + render_spectrogram (surface, render->spec_floor_db, mag_spec, max_mag, LEFT_BORDER, TOP_BORDER, width, height, render->gray_scale) ; - render_heat_map (surface, render->spec_floor_db, &heat_rect) ; + render_heat_map (surface, render->spec_floor_db, &heat_rect, render->gray_scale) ; render_spect_border (surface, render->filename, LEFT_BORDER, width, filelen / (1.0 * samplerate), TOP_BORDER, height, 0.5 * samplerate) ; render_heat_border (surface, render->spec_floor_db, &heat_rect) ; } else - render_spectrogram (surface, render->spec_floor_db, mag_spec, max_mag, 0, 0, width, height) ; + render_spectrogram (surface, render->spec_floor_db, mag_spec, max_mag, 0, 0, width, height, render->gray_scale) ; return ; } /* render_to_surface */ @@ -623,6 +650,7 @@ usage_exit (const char * argv0, int error) " --dyn-range= : Dynamic range (ie 100 for 100dB range)\n" " --no-border : Drop the border, scales, heat map and title\n" /*-" --log-freq : Use a logarithmic frquency scale\n" -*/ + " --gray-scale : Output gray pixels instead of a heat map\n" ) ; exit (error) ; @@ -633,7 +661,7 @@ main (int argc, char * argv []) { RENDER render = { NULL, NULL, NULL, 0, 0, - true, false, + true, false, false, SPEC_FLOOR_DB } ; int k ; @@ -659,6 +687,11 @@ main (int argc, char * argv []) continue ; } ; + if (strcmp (argv [k], "--gray-scale") == 0) + { render.gray_scale = true ; + continue ; + } ; + printf ("\nError : Bad command line argument '%s'\n", argv [k]) ; usage_exit (argv [0], 1) ; } ;