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/*****************************************************************************/
// Copyright 2006 Adobe Systems Incorporated
// All Rights Reserved.
//
// NOTICE: Adobe permits you to use, modify, and distribute this file in
// accordance with the terms of the Adobe license agreement accompanying it.
/*****************************************************************************/
/* $Id: //mondo/dng_sdk_1_4/dng_sdk/source/dng_temperature.cpp#1 $ */
/* $DateTime: 2012/05/30 13:28:51 $ */
/* $Change: 832332 $ */
/* $Author: tknoll $ */
#include "dng_temperature.h"
#include "dng_xy_coord.h"
/*****************************************************************************/
// Scale factor between distances in uv space to a more user friendly "tint"
// parameter.
static const real64 kTintScale = -3000.0;
/*****************************************************************************/
// Table from Wyszecki & Stiles, "Color Science", second edition, page 228.
struct ruvt
{
real64 r;
real64 u;
real64 v;
real64 t;
};
static const ruvt kTempTable [] =
{
{ 0, 0.18006, 0.26352, -0.24341 },
{ 10, 0.18066, 0.26589, -0.25479 },
{ 20, 0.18133, 0.26846, -0.26876 },
{ 30, 0.18208, 0.27119, -0.28539 },
{ 40, 0.18293, 0.27407, -0.30470 },
{ 50, 0.18388, 0.27709, -0.32675 },
{ 60, 0.18494, 0.28021, -0.35156 },
{ 70, 0.18611, 0.28342, -0.37915 },
{ 80, 0.18740, 0.28668, -0.40955 },
{ 90, 0.18880, 0.28997, -0.44278 },
{ 100, 0.19032, 0.29326, -0.47888 },
{ 125, 0.19462, 0.30141, -0.58204 },
{ 150, 0.19962, 0.30921, -0.70471 },
{ 175, 0.20525, 0.31647, -0.84901 },
{ 200, 0.21142, 0.32312, -1.0182 },
{ 225, 0.21807, 0.32909, -1.2168 },
{ 250, 0.22511, 0.33439, -1.4512 },
{ 275, 0.23247, 0.33904, -1.7298 },
{ 300, 0.24010, 0.34308, -2.0637 },
{ 325, 0.24702, 0.34655, -2.4681 },
{ 350, 0.25591, 0.34951, -2.9641 },
{ 375, 0.26400, 0.35200, -3.5814 },
{ 400, 0.27218, 0.35407, -4.3633 },
{ 425, 0.28039, 0.35577, -5.3762 },
{ 450, 0.28863, 0.35714, -6.7262 },
{ 475, 0.29685, 0.35823, -8.5955 },
{ 500, 0.30505, 0.35907, -11.324 },
{ 525, 0.31320, 0.35968, -15.628 },
{ 550, 0.32129, 0.36011, -23.325 },
{ 575, 0.32931, 0.36038, -40.770 },
{ 600, 0.33724, 0.36051, -116.45 }
};
/*****************************************************************************/
void dng_temperature::Set_xy_coord (const dng_xy_coord &xy)
{
// Convert to uv space.
real64 u = 2.0 * xy.x / (1.5 - xy.x + 6.0 * xy.y);
real64 v = 3.0 * xy.y / (1.5 - xy.x + 6.0 * xy.y);
// Search for line pair coordinate is between.
real64 last_dt = 0.0;
real64 last_dv = 0.0;
real64 last_du = 0.0;
for (uint32 index = 1; index <= 30; index++)
{
// Convert slope to delta-u and delta-v, with length 1.
real64 du = 1.0;
real64 dv = kTempTable [index] . t;
real64 len = sqrt (1.0 + dv * dv);
du /= len;
dv /= len;
// Find delta from black body point to test coordinate.
real64 uu = u - kTempTable [index] . u;
real64 vv = v - kTempTable [index] . v;
// Find distance above or below line.
real64 dt = - uu * dv + vv * du;
// If below line, we have found line pair.
if (dt <= 0.0 || index == 30)
{
// Find fractional weight of two lines.
if (dt > 0.0)
dt = 0.0;
dt = -dt;
real64 f;
if (index == 1)
{
f = 0.0;
}
else
{
f = dt / (last_dt + dt);
}
// Interpolate the temperature.
fTemperature = 1.0E6 / (kTempTable [index - 1] . r * f +
kTempTable [index ] . r * (1.0 - f));
// Find delta from black body point to test coordinate.
uu = u - (kTempTable [index - 1] . u * f +
kTempTable [index ] . u * (1.0 - f));
vv = v - (kTempTable [index - 1] . v * f +
kTempTable [index ] . v * (1.0 - f));
// Interpolate vectors along slope.
du = du * (1.0 - f) + last_du * f;
dv = dv * (1.0 - f) + last_dv * f;
len = sqrt (du * du + dv * dv);
du /= len;
dv /= len;
// Find distance along slope.
fTint = (uu * du + vv * dv) * kTintScale;
break;
}
// Try next line pair.
last_dt = dt;
last_du = du;
last_dv = dv;
}
}
/*****************************************************************************/
dng_xy_coord dng_temperature::Get_xy_coord () const
{
dng_xy_coord result;
// Find inverse temperature to use as index.
real64 r = 1.0E6 / fTemperature;
// Convert tint to offset is uv space.
real64 offset = fTint * (1.0 / kTintScale);
// Search for line pair containing coordinate.
for (uint32 index = 0; index <= 29; index++)
{
if (r < kTempTable [index + 1] . r || index == 29)
{
// Find relative weight of first line.
real64 f = (kTempTable [index + 1] . r - r) /
(kTempTable [index + 1] . r - kTempTable [index] . r);
// Interpolate the black body coordinates.
real64 u = kTempTable [index ] . u * f +
kTempTable [index + 1] . u * (1.0 - f);
real64 v = kTempTable [index ] . v * f +
kTempTable [index + 1] . v * (1.0 - f);
// Find vectors along slope for each line.
real64 uu1 = 1.0;
real64 vv1 = kTempTable [index] . t;
real64 uu2 = 1.0;
real64 vv2 = kTempTable [index + 1] . t;
real64 len1 = sqrt (1.0 + vv1 * vv1);
real64 len2 = sqrt (1.0 + vv2 * vv2);
uu1 /= len1;
vv1 /= len1;
uu2 /= len2;
vv2 /= len2;
// Find vector from black body point.
real64 uu3 = uu1 * f + uu2 * (1.0 - f);
real64 vv3 = vv1 * f + vv2 * (1.0 - f);
real64 len3 = sqrt (uu3 * uu3 + vv3 * vv3);
uu3 /= len3;
vv3 /= len3;
// Adjust coordinate along this vector.
u += uu3 * offset;
v += vv3 * offset;
// Convert to xy coordinates.
result.x = 1.5 * u / (u - 4.0 * v + 2.0);
result.y = v / (u - 4.0 * v + 2.0);
break;
}
}
return result;
}
/*****************************************************************************/
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