pq.go RawHistoryFolder

1package vulkan
2
3import (
4	"math"
5
6	"github.com/bnema/neferwl/internal/adapters/hdrcursor"
7)
8
9// srgbToLinear decodes a unit-range sRGB component.
10func srgbToLinear(v float64) float64 { return hdrcursor.SRGBToLinear(v) }
11
12// linearToSRGB encodes a unit-range linear component; the inverse of
13// srgbToLinear.
14func linearToSRGB(v float64) float64 {
15	if v <= 0.04045/12.92 {
16		return v * 12.92
17	}
18	return 1.055*math.Pow(v, 1/2.4) - 0.055
19}
20
21// pqEncode encodes absolute luminance in nits using SMPTE ST 2084.
22func pqEncode(nits float64) float64 { return hdrcursor.PQEncode(nits) }
23
24// hdrPixel transforms an unassociated sRGB triplet into BT.2020 PQ.
25func hdrPixel(red, green, blue, nits float64) (float64, float64, float64) {
26	r, g, b := srgbToLinear(red), srgbToLinear(green), srgbToLinear(blue)
27	return pqEncode((0.627404*r + 0.329283*g + 0.043313*b) * nits),
28		pqEncode((0.069097*r + 0.919540*g + 0.011362*b) * nits),
29		pqEncode((0.016391*r + 0.088013*g + 0.895595*b) * nits)
30}