diff options
Diffstat (limited to 'libs/ultrahdr/gainmapmath.cpp')
| -rw-r--r-- | libs/ultrahdr/gainmapmath.cpp | 149 |
1 files changed, 132 insertions, 17 deletions
diff --git a/libs/ultrahdr/gainmapmath.cpp b/libs/ultrahdr/gainmapmath.cpp index 37c3cf3d3b..ee15363b69 100644 --- a/libs/ultrahdr/gainmapmath.cpp +++ b/libs/ultrahdr/gainmapmath.cpp @@ -119,34 +119,39 @@ static float clampPixelFloat(float value) { return (value < 0.0f) ? 0.0f : (value > kMaxPixelFloat) ? kMaxPixelFloat : value; } -// See IEC 61966-2-1, Equation F.7. +// See IEC 61966-2-1/Amd 1:2003, Equation F.7. static const float kSrgbR = 0.2126f, kSrgbG = 0.7152f, kSrgbB = 0.0722f; float srgbLuminance(Color e) { return kSrgbR * e.r + kSrgbG * e.g + kSrgbB * e.b; } -// See ECMA TR/98, Section 7. -static const float kSrgbRCr = 1.402f, kSrgbGCb = 0.34414f, kSrgbGCr = 0.71414f, kSrgbBCb = 1.772f; +// See ITU-R BT.709-6, Section 3. +// Uses the same coefficients for deriving luma signal as +// IEC 61966-2-1/Amd 1:2003 states for luminance, so we reuse the luminance +// function above. +static const float kSrgbCb = 1.8556f, kSrgbCr = 1.5748f; -Color srgbYuvToRgb(Color e_gamma) { - return {{{ clampPixelFloat(e_gamma.y + kSrgbRCr * e_gamma.v), - clampPixelFloat(e_gamma.y - kSrgbGCb * e_gamma.u - kSrgbGCr * e_gamma.v), - clampPixelFloat(e_gamma.y + kSrgbBCb * e_gamma.u) }}}; +Color srgbRgbToYuv(Color e_gamma) { + float y_gamma = srgbLuminance(e_gamma); + return {{{ y_gamma, + (e_gamma.b - y_gamma) / kSrgbCb, + (e_gamma.r - y_gamma) / kSrgbCr }}}; } -// See ECMA TR/98, Section 7. -static const float kSrgbYR = 0.299f, kSrgbYG = 0.587f, kSrgbYB = 0.114f; -static const float kSrgbUR = -0.1687f, kSrgbUG = -0.3313f, kSrgbUB = 0.5f; -static const float kSrgbVR = 0.5f, kSrgbVG = -0.4187f, kSrgbVB = -0.0813f; +// See ITU-R BT.709-6, Section 3. +// Same derivation to BT.2100's YUV->RGB, below. Similar to srgbRgbToYuv, we +// can reuse the luminance coefficients since they are the same. +static const float kSrgbGCb = kSrgbB * kSrgbCb / kSrgbG; +static const float kSrgbGCr = kSrgbR * kSrgbCr / kSrgbG; -Color srgbRgbToYuv(Color e_gamma) { - return {{{ kSrgbYR * e_gamma.r + kSrgbYG * e_gamma.g + kSrgbYB * e_gamma.b, - kSrgbUR * e_gamma.r + kSrgbUG * e_gamma.g + kSrgbUB * e_gamma.b, - kSrgbVR * e_gamma.r + kSrgbVG * e_gamma.g + kSrgbVB * e_gamma.b }}}; +Color srgbYuvToRgb(Color e_gamma) { + return {{{ clampPixelFloat(e_gamma.y + kSrgbCr * e_gamma.v), + clampPixelFloat(e_gamma.y - kSrgbGCb * e_gamma.u - kSrgbGCr * e_gamma.v), + clampPixelFloat(e_gamma.y + kSrgbCb * e_gamma.u) }}}; } -// See IEC 61966-2-1, Equations F.5 and F.6. +// See IEC 61966-2-1/Amd 1:2003, Equations F.5 and F.6. float srgbInvOetf(float e_gamma) { if (e_gamma <= 0.04045f) { return e_gamma / 12.92f; @@ -178,13 +183,38 @@ Color srgbInvOetfLUT(Color e_gamma) { //////////////////////////////////////////////////////////////////////////////// // Display-P3 transformations -// See SMPTE EG 432-1, Table 7-2. +// See SMPTE EG 432-1, Equation 7-8. static const float kP3R = 0.20949f, kP3G = 0.72160f, kP3B = 0.06891f; float p3Luminance(Color e) { return kP3R * e.r + kP3G * e.g + kP3B * e.b; } +// See ITU-R BT.601-7, Sections 2.5.1 and 2.5.2. +// Unfortunately, calculation of luma signal differs from calculation of +// luminance for Display-P3, so we can't reuse p3Luminance here. +static const float kP3YR = 0.299f, kP3YG = 0.587f, kP3YB = 0.114f; +static const float kP3Cb = 1.772f, kP3Cr = 1.402f; + +Color p3RgbToYuv(Color e_gamma) { + float y_gamma = kP3YR * e_gamma.r + kP3YG * e_gamma.g + kP3YB * e_gamma.b; + return {{{ y_gamma, + (e_gamma.b - y_gamma) / kP3Cb, + (e_gamma.r - y_gamma) / kP3Cr }}}; +} + +// See ITU-R BT.601-7, Sections 2.5.1 and 2.5.2. +// Same derivation to BT.2100's YUV->RGB, below. Similar to p3RgbToYuv, we must +// use luma signal coefficients rather than the luminance coefficients. +static const float kP3GCb = kP3YB * kP3Cb / kP3YG; +static const float kP3GCr = kP3YR * kP3Cr / kP3YG; + +Color p3YuvToRgb(Color e_gamma) { + return {{{ clampPixelFloat(e_gamma.y + kP3Cr * e_gamma.v), + clampPixelFloat(e_gamma.y - kP3GCb * e_gamma.u - kP3GCr * e_gamma.v), + clampPixelFloat(e_gamma.y + kP3Cb * e_gamma.u) }}}; +} + //////////////////////////////////////////////////////////////////////////////// // BT.2100 transformations - according to ITU-R BT.2100-2 @@ -197,6 +227,8 @@ float bt2100Luminance(Color e) { } // See ITU-R BT.2100-2, Table 6, Derivation of colour difference signals. +// BT.2100 uses the same coefficients for calculating luma signal and luminance, +// so we reuse the luminance function here. static const float kBt2100Cb = 1.8814f, kBt2100Cr = 1.4746f; Color bt2100RgbToYuv(Color e_gamma) { @@ -206,6 +238,10 @@ Color bt2100RgbToYuv(Color e_gamma) { (e_gamma.r - y_gamma) / kBt2100Cr }}}; } +// See ITU-R BT.2100-2, Table 6, Derivation of colour difference signals. +// +// Similar to bt2100RgbToYuv above, we can reuse the luminance coefficients. +// // Derived by inversing bt2100RgbToYuv. The derivation for R and B are pretty // straight forward; we just invert the formulas for U and V above. But deriving // the formula for G is a bit more complicated: @@ -440,6 +476,85 @@ ColorTransformFn getHdrConversionFn(ultrahdr_color_gamut sdr_gamut, } } +// All of these conversions are derived from the respective input YUV->RGB conversion followed by +// the RGB->YUV for the receiving encoding. They are consistent with the RGB<->YUV functions in this +// file, given that we uses BT.709 encoding for sRGB and BT.601 encoding for Display-P3, to match +// DataSpace. + +Color yuv709To601(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + 0.101579f * e_gamma.u + 0.196076f * e_gamma.v, + 0.0f * e_gamma.y + 0.989854f * e_gamma.u + -0.110653f * e_gamma.v, + 0.0f * e_gamma.y + -0.072453f * e_gamma.u + 0.983398f * e_gamma.v }}}; +} + +Color yuv709To2100(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + -0.016969f * e_gamma.u + 0.096312f * e_gamma.v, + 0.0f * e_gamma.y + 0.995306f * e_gamma.u + -0.051192f * e_gamma.v, + 0.0f * e_gamma.y + 0.011507f * e_gamma.u + 1.002637f * e_gamma.v }}}; +} + +Color yuv601To709(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + -0.118188f * e_gamma.u + -0.212685f * e_gamma.v, + 0.0f * e_gamma.y + 1.018640f * e_gamma.u + 0.114618f * e_gamma.v, + 0.0f * e_gamma.y + 0.075049f * e_gamma.u + 1.025327f * e_gamma.v }}}; +} + +Color yuv601To2100(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + -0.128245f * e_gamma.u + -0.115879f * e_gamma.v, + 0.0f * e_gamma.y + 1.010016f * e_gamma.u + 0.061592f * e_gamma.v, + 0.0f * e_gamma.y + 0.086969f * e_gamma.u + 1.029350f * e_gamma.v }}}; +} + +Color yuv2100To709(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + 0.018149f * e_gamma.u + -0.095132f * e_gamma.v, + 0.0f * e_gamma.y + 1.004123f * e_gamma.u + 0.051267f * e_gamma.v, + 0.0f * e_gamma.y + -0.011524f * e_gamma.u + 0.996782f * e_gamma.v }}}; +} + +Color yuv2100To601(Color e_gamma) { + return {{{ 1.0f * e_gamma.y + 0.117887f * e_gamma.u + 0.105521f * e_gamma.v, + 0.0f * e_gamma.y + 0.995211f * e_gamma.u + -0.059549f * e_gamma.v, + 0.0f * e_gamma.y + -0.084085f * e_gamma.u + 0.976518f * e_gamma.v }}}; +} + +void transformYuv420(jr_uncompressed_ptr image, size_t x_chroma, size_t y_chroma, + ColorTransformFn fn) { + Color yuv1 = getYuv420Pixel(image, x_chroma * 2, y_chroma * 2 ); + Color yuv2 = getYuv420Pixel(image, x_chroma * 2 + 1, y_chroma * 2 ); + Color yuv3 = getYuv420Pixel(image, x_chroma * 2, y_chroma * 2 + 1); + Color yuv4 = getYuv420Pixel(image, x_chroma * 2 + 1, y_chroma * 2 + 1); + + yuv1 = fn(yuv1); + yuv2 = fn(yuv2); + yuv3 = fn(yuv3); + yuv4 = fn(yuv4); + + Color new_uv = (yuv1 + yuv2 + yuv3 + yuv4) / 4.0f; + + size_t pixel_y1_idx = x_chroma * 2 + y_chroma * 2 * image->width; + size_t pixel_y2_idx = (x_chroma * 2 + 1) + y_chroma * 2 * image->width; + size_t pixel_y3_idx = x_chroma * 2 + (y_chroma * 2 + 1) * image->width; + size_t pixel_y4_idx = (x_chroma * 2 + 1) + (y_chroma * 2 + 1) * image->width; + + uint8_t& y1_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y1_idx]; + uint8_t& y2_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y2_idx]; + uint8_t& y3_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y3_idx]; + uint8_t& y4_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y4_idx]; + + size_t pixel_count = image->width * image->height; + size_t pixel_uv_idx = x_chroma + y_chroma * (image->width / 2); + + uint8_t& u_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_count + pixel_uv_idx]; + uint8_t& v_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_count * 5 / 4 + pixel_uv_idx]; + + y1_uint = static_cast<uint8_t>(floor(yuv1.y * 255.0f + 0.5f)); + y2_uint = static_cast<uint8_t>(floor(yuv2.y * 255.0f + 0.5f)); + y3_uint = static_cast<uint8_t>(floor(yuv3.y * 255.0f + 0.5f)); + y4_uint = static_cast<uint8_t>(floor(yuv4.y * 255.0f + 0.5f)); + + u_uint = static_cast<uint8_t>(floor(new_uv.u * 255.0f + 128.0f + 0.5f)); + v_uint = static_cast<uint8_t>(floor(new_uv.v * 255.0f + 128.0f + 0.5f)); +} //////////////////////////////////////////////////////////////////////////////// // Gain map calculations |