/**
* cd_spectrum_planckian_new_full:
* @temperature: the temperature in Kelvin
* @start: the new spectrum start
* @end: the new spectrum end
* @resolution: the resolution to use when resampling
*
* Allocates a Planckian spectrum at a specific temperature.
*
* Return value: A newly allocated #CdSpectrum object
*
* Since: 1.3.1
**/
CdSpectrum *
cd_spectrum_planckian_new_full (gdouble temperature,
gdouble start,
gdouble end,
gdouble resolution)
{
CdSpectrum *s = NULL;
const gdouble c1 = 3.74183e-16; /* 2pi * h * c^2 */
const gdouble c2 = 1.4388e-2; /* h * c / k */
gdouble wl;
gdouble norm;
gdouble tmp;
guint i;
/* sanity check */
if (temperature < 1.0 || temperature > 1e6)
return NULL;
/* create spectrum with 1nm resolution */
s = cd_spectrum_sized_new (531);
s->id = g_strdup_printf ("Planckian@%.0fK", temperature);
cd_spectrum_set_start (s, start);
cd_spectrum_set_end (s, end);
/* see http://www.create.uwe.ac.uk/ardtalks/Schanda_paper.pdf, page 42 */
wl = 560 * 1e-9;
norm = 0.01 * (c1 * pow (wl, -5.0)) / (exp (c2 / (wl * temperature)) - 1.0);
for (i = 0; i < s->reserved_size; i++) {
wl = cd_spectrum_get_wavelength (s, i) * 1e-9;
tmp = (c1 * pow (wl, -5.0)) / (exp (c2 / (wl * temperature)) - 1.0);
cd_spectrum_add_value (s, tmp / norm);
}
return s;
}
/**
* osp_device_take_spectrum_internal:
**/
static CdSpectrum *
osp_device_take_spectrum_internal (GUsbDevice *device,
guint64 sample_duration,
GError **error)
{
CdSpectrum *sp;
gdouble val;
gsize data_len;
guint i;
g_autofree guint8 *data = NULL;
g_autoptr(GTimer) t = NULL;
/* set integral time in us */
if (!osp_device_send_command (device, OSP_CMD_SET_INTEGRATION_TIME,
(guint8 *) &sample_duration, 4, error))
return NULL;
/* get spectrum */
t = g_timer_new ();
if (!osp_device_query (device, OSP_CMD_GET_AND_SEND_RAW_SPECTRUM,
NULL, 0, &data, &data_len, error))
return NULL;
g_debug ("For integration of %.0fms, sensor took %.0fms",
sample_duration / 1000.f, g_timer_elapsed (t, NULL) * 1000.f);
/* check values */
if (data_len != 2048) {
g_set_error (error,
OSP_DEVICE_ERROR,
OSP_DEVICE_ERROR_INTERNAL,
"Expected %i bytes, got %" G_GSIZE_FORMAT,
2048, data_len);
return NULL;
}
/* export */
sp = cd_spectrum_sized_new (1024);
for (i = 0; i < 1024; i++) {
val = data[i*2+1] * 256 + data[i*2+0];
cd_spectrum_add_value (sp, val / (gdouble) 0xffff);
}
/* the maximum value the hardware can return is 0x3fff */
val = cd_spectrum_get_value_max (sp);
if (val > 0.25) {
g_set_error (error,
OSP_DEVICE_ERROR,
OSP_DEVICE_ERROR_INTERNAL,
"spectral max should be <= 0.25f, was %f",
val);
cd_spectrum_free (sp);
return NULL;
}
return sp;
}
/**
* cd_spectrum_subtract:
* @s1: a #CdSpectrum instance, e.g. a sample
* @s2: a #CdSpectrum instance, e.g. a dark calibration
* @resolution: the resolution to use when resampling
*
* Subtracts one spectral plot from another. If the spectra have the same start,
* end and the same number of data points they are not resampled.
*
* Return value: a #CdSpectrum instance
*
* Since: 1.3.1
**/
CdSpectrum *
cd_spectrum_subtract (CdSpectrum *s1, CdSpectrum *s2, gdouble resolution)
{
CdSpectrum *s;
gdouble max;
gdouble min;
gdouble nm;
guint i;
g_return_val_if_fail (s1 != NULL, NULL);
g_return_val_if_fail (s2 != NULL, NULL);
/* we can do this without resampling */
if (fabs (s1->start - s2->start) < 0.01f &&
fabs (s1->end - s2->end) < 0.01f &&
s1->data->len == s2->data->len) {
s = cd_spectrum_sized_new (s1->data->len);
s->id = g_strdup_printf ("%s-%s", s1->id, s2->id);
s->start = s1->start;
s->end = s1->end;
for (i = 0; i < 3; i++)
s->wavelength_cal[i] = s1->wavelength_cal[i];
for (i = 0; i < s1->data->len; i++) {
gdouble tmp;
tmp = cd_spectrum_get_value (s1, i) - cd_spectrum_get_value (s2, i);
cd_spectrum_add_value (s, tmp);
}
return s;
}
/* resample */
min = MIN (cd_spectrum_get_start (s1), cd_spectrum_get_start (s2));
max = MAX (cd_spectrum_get_end (s1), cd_spectrum_get_end (s2));
s = cd_spectrum_new ();
s->id = g_strdup_printf ("%s-%s", s1->id, s2->id);
s->start = min;
s->end = max;
for (nm = min; nm <= max; nm += resolution) {
gdouble tmp;
tmp = cd_spectrum_get_value_for_nm (s1, nm) -
cd_spectrum_get_value_for_nm (s2, nm);
cd_spectrum_add_value (s, tmp);
}
return s;
}
