mirror of
https://github.com/mpv-player/mpv
synced 2024-12-19 13:21:13 +00:00
c028d782c1
This automatically sets the gamma option depending on lighting conditions measured from the computer's ambient light sensor. sRGB – arguably the “sibling” to BT.709 for still images – has a reference viewing environment defined in its specification (IEC 61966-2-1:1999, see http://www.color.org/chardata/rgb/srgb.xalter). According to this data, the assumed ambient illuminance is 64 lux. This is the illuminance where the gamma that results from ICC color management is correct. On the other hand, BT.1886 formalizes that the gamma level for dim environments to be 2.40, and Apple resources (WWDC12: 2012 Session 523: Best practices for color management) define the BT.1886 dim at 16 lux. So the logic we apply is: * >= 64lux -> 1.961 gamma * =< 16lux -> 2.400 gamma * 16lux < x < 64lux -> logaritmic rescale of lux to gamma. The human perception of illuminance roughly follows a logaritmic scale of lux [1]. [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/dd319008%28v=vs.85%29.aspx
43 lines
1.3 KiB
C
43 lines
1.3 KiB
C
#include "test_helpers.h"
|
|
#include "video/out/gl_video.h"
|
|
|
|
static void test_scale_ambient_lux_limits(void **state) {
|
|
float x;
|
|
x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 16.0);
|
|
assert_double_equal(x, 2.40f);
|
|
|
|
x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 64.0);
|
|
assert_double_equal(x, 1.961f);
|
|
}
|
|
|
|
static void test_scale_ambient_lux_sign(void **state) {
|
|
float x;
|
|
x = gl_video_scale_ambient_lux(16.0, 64.0, 1.961, 2.40, 64.0);
|
|
assert_double_equal(x, 2.40f);
|
|
}
|
|
|
|
static void test_scale_ambient_lux_clamping(void **state) {
|
|
float x;
|
|
x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 0.0);
|
|
assert_double_equal(x, 2.40f);
|
|
}
|
|
|
|
static void test_scale_ambient_lux_log10_midpoint(void **state) {
|
|
float x;
|
|
// 32 corresponds to the the midpoint after converting lux to the log10 scale
|
|
x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 32.0);
|
|
float mid_gamma = (2.40 - 1.961) / 2 + 1.961;
|
|
assert_double_equal(x, mid_gamma);
|
|
}
|
|
|
|
int main(void) {
|
|
const UnitTest tests[] = {
|
|
unit_test(test_scale_ambient_lux_limits),
|
|
unit_test(test_scale_ambient_lux_sign),
|
|
unit_test(test_scale_ambient_lux_clamping),
|
|
unit_test(test_scale_ambient_lux_log10_midpoint),
|
|
};
|
|
return run_tests(tests);
|
|
}
|
|
|