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gdk: Handle negative values in all transfer function

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Make sure that for all eotfs/oetfs, eotf(x) == -eotf(-x)

In particular, don't pass negative values to pow() and cause
undefined behavior.
This commit is contained in:
Matthias Clasen 2024-08-13 15:47:17 -04:00
parent 79c2df8392
commit e1fbd52c29
1 changed files with 23 additions and 15 deletions
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38
gdk/gdkcolordefs.h
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@ -20,11 +20,17 @@
* and tests, and must not include other headers.
*/
static inline int
sign (float v)
{
return v < 0 ? -1 : 1;
}
static inline float
srgb_oetf (float v)
{
if (v > 0.0031308f)
return 1.055f * powf (v, 1.f / 2.4f) - 0.055f;
if (fabsf (v) > 0.0031308f)
return 1.055f * sign (v) * powf (fabsf (v), 1.f / 2.4f) - 0.055f;
else
return 12.92f * v;
}
@ -32,8 +38,8 @@ srgb_oetf (float v)
static inline float
srgb_eotf (float v)
{
if (v >= 0.04045f)
return powf (((v + 0.055f) / (1.f + 0.055f)), 2.4f);
if (fabsf (v) >= 0.04045f)
return sign (v) * powf (((fabsf (v) + 0.055f) / (1.f + 0.055f)), 2.4f);
else
return v / 12.92f;
}
@ -41,25 +47,25 @@ srgb_eotf (float v)
static inline float
gamma22_oetf (float v)
{
return powf (v, 1.f / 2.2f);
return sign (v) * powf (fabsf (v), 1.f / 2.2f);
}
static inline float
gamma22_eotf (float v)
{
return powf (v, 2.2f);
return sign (v) * powf (fabsf (v), 2.2f);
}
static inline float
gamma28_oetf (float v)
{
return powf (v, 1.f / 2.8f);
return sign (v) * powf (fabsf (v), 1.f / 2.8f);
}
static inline float
gamma28_eotf (float v)
{
return powf (v, 2.8f);
return sign (v) * powf (fabsf (v), 2.8f);
}
static inline float
@ -71,9 +77,10 @@ pq_eotf (float v)
float c2 = 2413.0 / (1 << 7);
float c3 = 2392.0 / (1 << 7);
float x = powf (MAX ((powf (v, minv) - c1), 0) / (c2 - (c3 * (powf (v, minv)))), ninv);
float x = powf (fabsf (v), minv);
x = powf (MAX ((x - c1), 0) / (c2 - (c3 * x)), ninv);
return x * 10000 / 203.0;
return sign (v) * x * 10000 / 203.0;
}
static inline float
@ -86,7 +93,8 @@ pq_oetf (float v)
float c2 = 2413.0 / (1 << 7);
float c3 = 2392.0 / (1 << 7);
return powf (((c1 + (c2 * powf (x, n))) / (1 + (c3 * powf (x, n)))), m);
x = powf (fabsf (x), n);
return sign (v) * powf (((c1 + (c2 * x)) / (1 + (c3 * x))), m);
}
static inline float
@ -95,10 +103,10 @@ bt709_eotf (float v)
const float a = 1.099;
const float d = 0.0812;
if (v < d)
if (fabsf (v) < d)
return v / 4.5f;
else
return powf ((v + (a - 1)) / a, 1 / 0.45f);
return sign (v) * powf ((fabsf (v) + (a - 1)) / a, 1 / 0.45f);
}
static inline float
@ -107,10 +115,10 @@ bt709_oetf (float v)
const float a = 1.099;
const float b = 0.018;
if (v < b)
if (fabsf (v) < b)
return v * 4.5f;
else
return a * powf (v, 0.45f) - (a - 1);
return a * sign (v) * powf (fabsf (v), 0.45f) - (a - 1);
}
static inline float