ColorTransform.cpp

/******************************************************************************
    QtAV:  Multimedia framework based on Qt and FFmpeg
    Copyright (C) 2012-2016 Wang Bin <wbsecg1@gmail.com>

*   This file is part of QtAV (from 2014)

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
******************************************************************************/

#include "ColorTransform.h"
#include <QtCore/qmath.h>

namespace QtAV {

// http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
static const QMatrix4x4 kXYZ2sRGB(3.2404542f,  -1.5371385f, -0.4985314f, 0.0f,
                                  -0.9692660f,  1.8760108f,  0.0415560f, 0.0f,
                                   0.0556434f, -0.2040259f,  1.0572252f, 0.0f,
                                 0.0f, 0.0f, 0.0f, 1.0f);
// http://www.cs.utah.edu/~halzahaw/CS7650/Project2/project2_index.html no gamma correction
static const QMatrix4x4 kXYZ_RGB(2.5623f,  -1.1661f, -0.3962f, 0.0f,
                                 -1.0215f,  1.9778f, 0.0437f,  0.0f,
                                  0.0752f, -0.2562f, 1.1810f,  0.0f,
                                 0.0f, 0.0f, 0.0f, 1.0f);

static const QMatrix4x4 kGBR2RGB = QMatrix4x4(0, 0, 1, 0,
                                              1, 0, 0, 0,
                                              0, 1, 0, 0,
                                              0, 0, 0, 1);

static const QMatrix4x4 yuv2rgb_bt601 =
           QMatrix4x4(
                1.0f,  0.000f,  1.402f, 0.0f,
                1.0f, -0.344f, -0.714f, 0.0f,
                1.0f,  1.772f,  0.000f, 0.0f,
                0.0f,  0.000f,  0.000f, 1.0f)
            *
            QMatrix4x4(
                1.0f, 0.0f, 0.0f, 0.0f,
                0.0f, 1.0f, 0.0f, -0.5f,
                0.0f, 0.0f, 1.0f, -0.5f,
                0.0f, 0.0f, 0.0f, 1.0f)
        ;
static const QMatrix4x4 yuv2rgb_bt709 =
           QMatrix4x4(
                1.0f,  0.000f,  1.5701f, 0.0f,
                1.0f, -0.187f, -0.4664f, 0.0f,
                1.0f,  1.8556f, 0.000f,  0.0f,
                0.0f,  0.000f,  0.000f,  1.0f)
            *
            QMatrix4x4(
                1.0f, 0.0f, 0.0f, 0.0f,
                0.0f, 1.0f, 0.0f, -0.5f,
                0.0f, 0.0f, 1.0f, -0.5f,
                0.0f, 0.0f, 0.0f, 1.0f)
        ;

const QMatrix4x4& ColorTransform::YUV2RGB(ColorSpace cs)
{
    switch (cs) {
    case ColorSpace_BT601:
        return yuv2rgb_bt601;
    case ColorSpace_BT709:
        return yuv2rgb_bt709;
    default:
        return yuv2rgb_bt601;
    }
    return yuv2rgb_bt601;
}

// For yuv->rgb, assume yuv is full range before convertion, rgb is full range after convertion. so if input yuv is limited range, transform to full range first. If display rgb is limited range, transform to limited range at last.
// *ColorRangeYUV(...)
static QMatrix4x4 ColorRangeYUV(ColorRange from, ColorRange to)
{
    if (from == to)
        return QMatrix4x4();
    static const qreal Y2 = 235, Y1 = 16, C2 = 240, C1 = 16;
    static const qreal s = 255; //TODO: can be others
    if (from == ColorRange_Limited) { //TODO: Unknown. But what if realy want unknown?
        qDebug("input yuv limited range");
        // [Y1, Y2] => [0, s]
        QMatrix4x4 m;
        m.scale(s/(Y2 - Y1), s/(C2 - C1), s/(C2 - C1));
        m.translate(-Y1/s, -C1/s, -C1/s);
        return m;
    }
    if (from == ColorRange_Full) {
        // [0, s] => [Y1, Y2]
        QMatrix4x4 m;
        m.translate(Y1/s, C1/s, C1/s);
        m.scale((Y2 - Y1)/s, (C2 - C1)/s, (C2 - C1)/s);
        return m;
    }
    // ColorRange_Unknown
    return QMatrix4x4();
}

// ColorRangeRGB(...)*
static QMatrix4x4 ColorRangeRGB(ColorRange from, ColorRange to)
{
    if (from == to)
        return QMatrix4x4();
    static const qreal R2 = 235, R1 = 16;
    static const qreal s = 255;
    if (to == ColorRange_Limited) {
        qDebug("output rgb limited range");
        QMatrix4x4 m;
        m.translate(R1/s, R1/s, R1/s);
        m.scale((R2 - R1)/s, (R2 - R1)/s, (R2 - R1)/s);
        return m;
    }
    if (to == ColorRange_Full) { // TODO: Unknown
        QMatrix4x4 m;
        m.scale(s/(R2 - R1), s/(R2 - R1), s/(R2 - R1));
        m.translate(-s/R1, -s/R1, -s/R1);
        return m;
    }
    return QMatrix4x4();
}

class ColorTransform::Private : public QSharedData
{
public:
    Private()
        : recompute(true)
        , cs_in(ColorSpace_RGB)
        , cs_out(ColorSpace_RGB)
        , range_in(ColorRange_Limited)
        , range_out(ColorRange_Full)
        , hue(0)
        , saturation(0)
        , contrast(0)
        , brightness(0)
        , bpc_scale(1.0)
        , a_bpc_scale(false)
    {}
    Private(const Private& other)
        : QSharedData(other)
        , recompute(true)
        , cs_in(ColorSpace_RGB)
        , cs_out(ColorSpace_RGB)
        , range_in(ColorRange_Limited)
        , range_out(ColorRange_Full)
        , hue(0)
        , saturation(0)
        , contrast(0)
        , brightness(0)
        , bpc_scale(1.0)
        , a_bpc_scale(false)
    {}
    ~Private() {}

    void reset() {
        recompute = true;
        //cs_in = cs_out = ColorSpace_RGB; ///
        //range_in = range_out = ColorRange_Unknown;
        hue = 0;
        saturation = 0;
        contrast = 0;
        brightness = 0;
        bpc_scale = 1.0;
        a_bpc_scale = false;
        M.setToIdentity();
    }
    // TODO: optimize for other color spaces
    void compute() const {
        recompute = false;
        //http://docs.rainmeter.net/tips/colormatrix-guide
        //http://www.graficaobscura.com/matrix/index.html
        //http://beesbuzz.biz/code/hsv_color_transforms.php
        // ??
        const float b = brightness;
        // brightness R,G,B
        QMatrix4x4 B(1, 0, 0, b,
                     0, 1, 0, b,
                     0, 0, 1, b,
                     0, 0, 0, 1);
        // Contrast (offset) R,G,B
        const float c = contrast+1.0;
        const float t = (1.0 - c) / 2.0;
        QMatrix4x4 C(c, 0, 0, t,
                     0, c, 0, t,
                     0, 0, c, t,
                     0, 0, 0, 1);
        // Saturation
        const float wr = 0.3086f;
        const float wg = 0.6094f;
        const float wb = 0.0820f;
        float s = saturation + 1.0f;
        QMatrix4x4 S(
            (1.0f - s)*wr + s, (1.0f - s)*wg    , (1.0f - s)*wb    , 0.0f,
            (1.0f - s)*wr    , (1.0f - s)*wg + s, (1.0f - s)*wb    , 0.0f,
            (1.0f - s)*wr    , (1.0f - s)*wg    , (1.0f - s)*wb + s, 0.0f,
                         0.0f,              0.0f,              0.0f, 1.0f
        );
        // Hue
        const float n = 1.0f / sqrtf(3.0f);       // normalized hue rotation axis: sqrt(3)*(1 1 1)
        const float h = hue*M_PI;               // hue rotation angle
        const float hc = cosf(h);
        const float hs = sinf(h);
        QMatrix4x4 H(     // conversion of angle/axis representation to matrix representation
            n*n*(1.0f - hc) + hc  , n*n*(1.0f - hc) - n*hs, n*n*(1.0f - hc) + n*hs, 0.0f,
            n*n*(1.0f - hc) + n*hs, n*n*(1.0f - hc) + hc  , n*n*(1.0f - hc) - n*hs, 0.0f,
            n*n*(1.0f - hc) - n*hs, n*n*(1.0f - hc) + n*hs, n*n*(1.0f - hc) + hc  , 0.0f,
                              0.0f,                   0.0f,                   0.0f, 1.0f
        );

        // B*C*S*H*rgb_range_mat(*yuv2rgb*yuv_range_mat)*bpc_scale
        M = B*C*S*H;
        // M *= rgb_range_translate*rgb_range_scale
        // TODO: transform to output color space other than RGB
        switch (cs_out) {
        case ColorSpace_XYZ:
            M = kXYZ2sRGB.inverted() * M;
            break;
        case ColorSpace_RGB:
            M *= ColorRangeRGB(ColorRange_Full, range_out);
            break;
        case ColorSpace_GBR:
            M *= ColorRangeRGB(ColorRange_Full, range_out);
            M = kGBR2RGB.inverted() * M;
            break;
        default:
            M = YUV2RGB(cs_out).inverted() * M;
            break;
        }

        switch (cs_in) {
        case ColorSpace_XYZ:
            M *= kXYZ2sRGB;
            break;
        case ColorSpace_RGB:
            break;
        case ColorSpace_GBR:
            M *= kGBR2RGB;
            break;
        default:
            M *= YUV2RGB(cs_in)*ColorRangeYUV(range_in, ColorRange_Full);
            break;
        }
        if (bpc_scale != 1.0 && cs_in != ColorSpace_XYZ) { // why no range correction for xyz?
            //qDebug("bpc scale: %f", bpc_scale);
            M *= QMatrix4x4(bpc_scale, 0, 0, 0,
                            0, bpc_scale, 0, 0,
                            0, 0, bpc_scale, 0,
                            0, 0, 0, a_bpc_scale ? bpc_scale : 1); // scale alpha channel too
        }
        //qDebug() << "color mat: " << M;
    }

    mutable bool recompute;
    ColorSpace cs_in, cs_out;
    ColorRange range_in, range_out;
    qreal hue, saturation, contrast, brightness;
    qreal bpc_scale;
    bool a_bpc_scale;
    mutable QMatrix4x4 M; // count the transformations between spaces
};

ColorTransform::ColorTransform()
    : d(new Private())
{
}

ColorTransform::~ColorTransform()
{
}

ColorSpace ColorTransform::inputColorSpace() const
{
    return d->cs_in;
}

void ColorTransform::setInputColorSpace(ColorSpace cs)
{
    if (d->cs_in == cs)
        return;
    d->cs_in = cs;
    d->recompute = true; //TODO: only recompute color space transform
}

ColorSpace ColorTransform::outputColorSpace() const
{
    return d->cs_out;
}

void ColorTransform::setOutputColorSpace(ColorSpace cs)
{
    if (d->cs_out == cs)
        return;
    d->cs_out = cs;
    d->recompute = true; //TODO: only recompute color space transform
}

ColorRange ColorTransform::inputColorRange() const
{
    return d->range_in;
}

void ColorTransform::setInputColorRange(ColorRange value)
{
    if (d->range_in == value)
        return;
    d->range_in = value;
    d->recompute = true;
}

ColorRange ColorTransform::outputColorRange() const
{
    return d->range_out;
}

void ColorTransform::setOutputColorRange(ColorRange value)
{
    if (d->range_out == value)
        return;
    d->range_out = value;
    d->recompute = true;
}

QMatrix4x4 ColorTransform::matrix() const
{
    if (d->recompute)
        d->compute();
    return d->M;
}

const QMatrix4x4& ColorTransform::matrixRef() const
{
    if (d->recompute)
        d->compute();
    return d->M;
}

/*!
 * \brief reset
 *   set to identity
 */
void ColorTransform::reset()
{
    d->reset();
}

void ColorTransform::setBrightness(qreal brightness)
{
    if (d->brightness == brightness)
        return;
    d->brightness = brightness;
    d->recompute = true;
}

qreal ColorTransform::brightness() const
{
    return d->brightness;
}

// -1~1
void ColorTransform::setHue(qreal hue)
{
    if (d->hue == hue)
        return;
    d->hue = hue;
    d->recompute = true;
}

qreal ColorTransform::hue() const
{
    return d->hue;
}

void ColorTransform::setContrast(qreal contrast)
{
    if (d->contrast == contrast)
        return;
    d->contrast = contrast;
    d->recompute = true;
}

qreal ColorTransform::contrast() const
{
    return d->contrast;
}

void ColorTransform::setSaturation(qreal saturation)
{
    if (d->saturation == saturation)
        return;
    d->saturation = saturation;
    d->recompute = true;
}

qreal ColorTransform::saturation() const
{
    return d->saturation;
}

void ColorTransform::setChannelDepthScale(qreal value, bool scaleAlpha)
{
    if (d->bpc_scale == value && d->a_bpc_scale == scaleAlpha)
        return;
    qDebug("ColorTransform bpc_scale %f=>%f, scale alpha: %d=>%d", d->bpc_scale, value, d->a_bpc_scale, scaleAlpha);
    d->bpc_scale = value;
    d->a_bpc_scale = scaleAlpha;
    d->recompute = true;
}
} //namespace QtAV