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isp:sample_ae_implementation_in_c [2018/06/16 22:28] – [Helpers] Igor Yefmovisp:sample_ae_implementation_in_c [2022/04/04 23:32] (current) – external edit 127.0.0.1
Line 36: Line 36:
     return 0;     return 0;
 } }
 +
 +}</code>
 +
 +====== PerPart ======
 +This helper class is to avoid stupid arithmetic errors when mixing various ratios, like absolute ratios, percentages (%), per-milles(‰), parts-per-million (ppm), etc. It also helps with gracefully handling division by zero (which results in defaulting the result of such ratio to ''0'').
 +
 +In addition a few helpful user-defined literals are provided for better code readability when it comes to constants.
 +
 +This is a super-minimalistic class that doesn't pretend to be production-quality.
 +
 +<code c++>namespace{
 +
 +struct PerPart{
 +    PerPart(long double _val = 0.f) : m_val(_val) {}  // 1.0f == 100_pcnt
 +    PerPart(unsigned long long int _val, unsigned long long int _div)
 +        : PerPart(_div == 0 ? 0.f : static_cast<long double>(_val) / _div)
 +    {}
 +    operator long double() const { return m_val; }
 +    int pcnt() const { return static_cast<int>(round(m_val * 100)); }
 +
 +private:
 +    long double m_val = 0.f;
 +};
 +
 +PerPart operator"" _pcnt(unsigned long long int _val){return PerPart(_val, 100);}
 +PerPart operator"" _pmille(unsigned long long int _val){return PerPart(_val, 1000);}
 +PerPart operator"" _ppm(unsigned long long int _val){return PerPart(_val, 1000 * 1000);}
  
 }</code> }</code>
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     using Val = IImgSensor::Value;  // shortcut for typing out the full type qualifier     using Val = IImgSensor::Value;  // shortcut for typing out the full type qualifier
     IImgSensor & m_ov;              // OmniVision sensor interface     IImgSensor & m_ov;              // OmniVision sensor interface
 +    const PerPart m_hysteresis;     // tolerance +/- for how accurate/sensitive the correction should be
  
     struct{     struct{
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 A bulk of (quite simplistic) calculations is performed with data in ''_stats'' and the results are stored in the ''m_vars'' struct: A bulk of (quite simplistic) calculations is performed with data in ''_stats'' and the results are stored in the ''m_vars'' struct:
  
-<code c++>AE::AE(IImgSensor * _ov, const ImgStats & _stats, const PerPart & _pp, int _tgtLuma)+<code c++>AE::AE(IImgSensor * _ov, const ImgStats & _stats, const PerPart & _pp, int _tgtLuma, const PerPart & _hysteresis)
     : m_ov(*_ov)     : m_ov(*_ov)
-    , m_stats(_stats)+    , m_hysteresis(_hysteresis)
 { {
     m_vars.underExposed = _triggeredLeft(_stats, _pp);     m_vars.underExposed = _triggeredLeft(_stats, _pp);
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     m_vars.adjY += (1 - m_vars.adjY) * 5 / 8;  // be 62.5% less aggressive than requested to avoid oscillations     m_vars.adjY += (1 - m_vars.adjY) * 5 / 8;  // be 62.5% less aggressive than requested to avoid oscillations
  
-    if(m_vars.overExposed > 60 && m_vars.adjY < 1){+    if(m_vars.overExposed > 60 && m_vars.adjY < 1 - m_hysteresis){
         m_vars.actionRH = Action::dec;  // plenty of pixels at level 60+ and we were asked to dim the image         m_vars.actionRH = Action::dec;  // plenty of pixels at level 60+ and we were asked to dim the image
-    }else if(m_vars.overExposed > 250 && m_vars.adjY <= 1){+    }else if(m_vars.overExposed > 250 && m_vars.adjY <= 1 - m_hysteresis){
         m_vars.actionRH = Action::dec;  // too many overexposed pixels and NOT increasing brightness         m_vars.actionRH = Action::dec;  // too many overexposed pixels and NOT increasing brightness
-    }else if(m_vars.overExposed < 250 && m_vars.adjY > 1){+    }else if(m_vars.overExposed < 250 && m_vars.adjY > 1 + m_hysteresis){
         m_vars.actionRH = Action::inc;  // there's room to grow and asked to increase brightness         m_vars.actionRH = Action::inc;  // there's room to grow and asked to increase brightness
     }else{     }else{
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 }</code> }</code>
  
 +====== Sample usage ======
 +
 +This is a copy-paste of the code used in [[manual:Aria]] utility for the POC. This code has minimal comments but should be fairly easy to follow:
 +
 +<code c++>namespace{
 +
 +static CString _corrOp2Txt(AE::CorrOp _op){
 +    using op = AE::CorrOp;
 +    switch(_op){
 +    case op::noop:      return {};
 +    case op::inc_exp:   return L"+++ Increasing Exposure";
 +    case op::inc_gl:    return L"+++ Increasing GLOBAL gain";
 +    case op::inc_green: return L"+++ PANIC! Increasing GREEN gain";
 +    case op::dec_exp:   return L"--- Reducing Exposure";
 +    case op::dec_gl:    return L"--- Reducing GLOBAL gain";
 +    case op::dec_green: return L"--- Reducing GREEN gain";
 +    }
 +    return {};
 +}
 +
 +}
 +
 +
 +void ImgAnalyzerDlg::_aeInfo()
 +{
 +    if(((CButton *)(GetDlgItem(IDC_CHECK_ISA_AE)))->GetCheck() != BST_CHECKED){
 +        return;
 +    }
 +    const auto & stats = m_analyzer.getStats();
 +    const auto correct = ((CButton*)(GetDlgItem(IDC_CHECK_ISA_AE_CORRECT)))->GetCheck() == BST_CHECKED;
 +    const auto aeTolerance = PerPart(GetDlgItemInt(IDC_EDIT_ISA_AE_RIGHT, NULL, FALSE), 1000);
 +    const int aeTgtLuma = GetDlgItemInt(IDC_EDIT_ISA_AE_BRIGHTNESS, NULL, FALSE);
 +    const PerPart aeHysteresis{GetDlgItemInt(IDC_EDIT_ISA_AE_HYSTERESIS, NULL, FALSE), 100};
 +    AE ae{m_fx3.sensor(), stats, aeTolerance, aeTgtLuma, aeHysteresis};
 +    const auto rez = ae(correct);
 +
 +    // display the information
 +    {
 +        const PerPart pxUsed{stats.ae.pixels, stats.total.pixels};
 +        CString msg;
 +        msg.AppendFormat(L"Pixels used: %d (%.1f%%)\n", stats.ae.pixels, pxUsed * 100);
 +        msg.AppendFormat(L"Under/over-exposed: %d/%d\n", rez.underExposed, rez.overExposed);
 +        msg.AppendFormat(L"BL adj.: %d\n", rez.adjBL);
 +        msg.AppendFormat(L"Avg Y.: %d\n", rez.avgY);
 +        msg.AppendFormat(L"Brightness adj.: %.2f\n", rez.adjY);
 +        msg += _corrOp2Txt(ae.details().op);
 +        SetDlgItemTextW(IDC_STATIC_ISA_AE, msg);
 +    }
 +}
 +</code>
 +
 +====== Initial values ======
 +
 +Following are the initial defaults for the variables that affect the process of automatic image brightness (Black Level, Exposure, Gains) adjustment:
 +^ Name (as seen in ''%%ImgAnalyzerDlg%%::_aeInfo()'' above) ^ Value ^
 +| ''aeTolerance'' | ''1/1000'' |
 +| ''aeTgtLuma'' | ''90'' |
 +| ''aeHysteresis'' | ''5/100'' |
 +| "center window" dimensions | ''50%'' vertically and horizontally, centered at image's center |

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