ILHDR Interface Reference

This interface provide functionalities of High Dynamic Range Imaging(HDR). More...

Inheritance diagram for ILHDR:

Public Member Functions
LPVErrorCode	BuildCRF (ILImageList *imgList, LArray< double > exposureTimes)
void	ExposureFusion (ILImageList *imgList, ILImage *result, double contrastWeight, double saturationWeight, double exposureWeight)
void	ToneMapping (ILImageList *imgList, ILImage *result, double gamma, double contrastEnhance, double saturationEnhance)
Public Member Functions inherited from ILObject
ILObject *	Copy ()
LPVErrorCode	Load (LString filename)
void	Reset ()
LPVErrorCode	Save (LString filename)
BOOL	Valid ()

Detailed Description

This interface provide functionalities of High Dynamic Range Imaging(HDR).

HDR imaging works with images that captured with different exposure settings. We provide two approach here:

1. Tone mapping, it firstly estimate the camera response function(CRf) based on the known exposure times, then recover the true irradiance image for the scene, and apply a tone-mapping algorithm to visualize this final image. It's the most popular way of processing an HDR image.
2. Exposure fusion, blend a bracketed exposure sequence into a high quality image, without camera response curve calibration. It's much simpler to use and the resulting image quality is comparable to tone-mapping method.

To use this interface, you should create a LHDR object.

Example Code

C++

Code snippets: snippets/HDR.cpp

ILHDRPtr hdrOp = LHDR::Create();
// 1. tone mapping
std::vector<double> exposureTimes = { 10000, 15000, 20000 };
LPVErrorCode err = hdrOp->BuildCRF(imgList, exposureTimes);
if (err != LPVErrorCode::LPVNoError) return; // handle error
hdrOp->ToneMapping(imgList, resultImg1, 1, 4, 1);
// 2. exposure fusion
hdrOp->ExposureFusion(imgList, resultImg2, 1, 1, 1);

C#

Code snippets: snippets/HDR.cs

LHDR hdrOp = new LHDR();
// 1. tone mapping
double[] exposureTimes = { 10000, 15000, 20000 };
LPVErrorCode err = hdrOp.BuildCRF(imgList, exposureTimes);
if (err != LPVErrorCode.LPVNoError) return; // handle error
hdrOp.ToneMapping(imgList, resultImg1, 1, 4, 1);
// 2. exposure fusion
hdrOp.ExposureFusion(imgList, resultImg2, 1, 1, 1);

COM

ILHDRPtr hdrOp = LHDR::Create();
// or, ILHDRPtr hdrOp(__uuidof(LHDR)), for absence of built-in Create functions (before 2.2.0)
// 1. tone mapping
CComSafeArray<double> exposureTimes;
exposureTimes.Add(10000);
exposureTimes.Add(15000);
exposureTimes.Add(20000);
LPVErrorCode err = hdrOp->BuildCRF(imgList, exposureTimes);
if (err != LPVErrorCode::LPVNoError) return; // handle error
hdrOp->ToneMapping(imgList, resultImg1, 1, 4, 1);
// 2. exposure fusion
hdrOp->ExposureFusion(imgList, resultImg2, 1, 1, 1);

Member Function Documentation

BuildCRF()

LPVErrorCode BuildCRF	(	ILImageList *	imgList,
		LArray< double >	exposureTimes
	)

Calibrate the CRF.

Parameters

[in]	imgList	The input images with different exposure settings
[in]	exposureTimes	The exposure times corresponding to the images, in μs

Return values

error

Return error code if anything is wrong.

ExposureFusion()

void ExposureFusion	(	ILImageList *	imgList,
		ILImage *	result,
		double	contrastWeight,
		double	saturationWeight,
		double	exposureWeight
	)

HDR imaging using exposure fusion approach.

Parameters

[in]	imgList	The input images with different exposure settings
[out]	result	Return result image
[in]	contrastWeight	The weight of contrast, by default, it's 1.
[in]	saturationWeight	The weight of saturation, by default it's 1.
[in]	exposureWeight	The weight of exposure, by default, it's 1.

ToneMapping()

void ToneMapping	(	ILImageList *	imgList,
		ILImage *	result,
		double	gamma,
		double	contrastEnhance,
		double	saturationEnhance
	)

HDR imaging using tone-mapping approach, the CRF is required.

Parameters

[in]	imgList	The input images with different exposure settings
[out]	result	Return result image
[in]	gamma	The gamma correction, 1(default) implies no correction, > 1 brightens the image and < 1 darkens it.
[in]	contrastEnhance	The contrast enhancement, resulting on logarithmic scale, i.e. \( log(max / min) \), where max and min are maximum and minimum luminance values of the resulting image. The default value is 4.
[in]	saturationEnhance	The saturation enhancement, 1(default) preserves saturation, > 1 increase saturation while < 1 decrease it.

See also

BuildCRF()