HDR imaging

クラス
class	cv::Tonemap
	Base class for tonemapping algorithms - tools that are used to map HDR image to 8-bit range. [詳解]
class	cv::TonemapDrago
	Adaptive logarithmic mapping is a fast global tonemapping algorithm that scales the image in logarithmic domain. [詳解]
class	cv::TonemapReinhard
	This is a global tonemapping operator that models human visual system. [詳解]
class	cv::TonemapMantiuk
	This algorithm transforms image to contrast using gradients on all levels of gaussian pyramid, transforms contrast values to HVS response and scales the response. After this the image is reconstructed from new contrast values. [詳解]
class	cv::AlignExposures
	The base class for algorithms that align images of the same scene with different exposures [詳解]
class	cv::AlignMTB
	This algorithm converts images to median threshold bitmaps (1 for pixels brighter than median luminance and 0 otherwise) and than aligns the resulting bitmaps using bit operations. [詳解]
class	cv::CalibrateCRF
	The base class for camera response calibration algorithms. [詳解]
class	cv::CalibrateDebevec
	Inverse camera response function is extracted for each brightness value by minimizing an objective function as linear system. Objective function is constructed using pixel values on the same position in all images, extra term is added to make the result smoother. [詳解]
class	cv::CalibrateRobertson
	Inverse camera response function is extracted for each brightness value by minimizing an objective function as linear system. This algorithm uses all image pixels. [詳解]
class	cv::MergeExposures
	The base class algorithms that can merge exposure sequence to a single image. [詳解]
class	cv::MergeDebevec
	The resulting HDR image is calculated as weighted average of the exposures considering exposure values and camera response. [詳解]
class	cv::MergeMertens
	Pixels are weighted using contrast, saturation and well-exposedness measures, than images are combined using laplacian pyramids. [詳解]
class	cv::MergeRobertson
	The resulting HDR image is calculated as weighted average of the exposures considering exposure values and camera response. [詳解]

列挙型
enum	{ LDR_SIZE = 256 }

関数
CV_EXPORTS_W Ptr< Tonemap >	cv::createTonemap (float gamma=1.0f)
	Creates simple linear mapper with gamma correction [詳解]
CV_EXPORTS_W Ptr< TonemapDrago >	cv::createTonemapDrago (float gamma=1.0f, float saturation=1.0f, float bias=0.85f)
	Creates TonemapDrago object [詳解]
CV_EXPORTS_W Ptr< TonemapReinhard >	cv::createTonemapReinhard (float gamma=1.0f, float intensity=0.0f, float light_adapt=1.0f, float color_adapt=0.0f)
	Creates TonemapReinhard object [詳解]
CV_EXPORTS_W Ptr< TonemapMantiuk >	cv::createTonemapMantiuk (float gamma=1.0f, float scale=0.7f, float saturation=1.0f)
	Creates TonemapMantiuk object [詳解]
CV_EXPORTS_W Ptr< AlignMTB >	cv::createAlignMTB (int max_bits=6, int exclude_range=4, bool cut=true)
	Creates AlignMTB object [詳解]
CV_EXPORTS_W Ptr< CalibrateDebevec >	cv::createCalibrateDebevec (int samples=70, float lambda=10.0f, bool random=false)
	Creates CalibrateDebevec object [詳解]
CV_EXPORTS_W Ptr< CalibrateRobertson >	cv::createCalibrateRobertson (int max_iter=30, float threshold=0.01f)
	Creates CalibrateRobertson object [詳解]
CV_EXPORTS_W Ptr< MergeDebevec >	cv::createMergeDebevec ()
	Creates MergeDebevec object
CV_EXPORTS_W Ptr< MergeMertens >	cv::createMergeMertens (float contrast_weight=1.0f, float saturation_weight=1.0f, float exposure_weight=0.0f)
	Creates MergeMertens object [詳解]
CV_EXPORTS_W Ptr< MergeRobertson >	cv::createMergeRobertson ()
	Creates MergeRobertson object

詳解

This section describes high dynamic range imaging algorithms namely tonemapping, exposure alignment, camera calibration with multiple exposures and exposure fusion.

@defgroup photo_decolor Contrast Preserving Decolorization

Useful links:

http://www.cse.cuhk.edu.hk/leojia/projects/color2gray/index.html

@defgroup photo_clone Seamless Cloning

Useful links:

https://www.learnopencv.com/seamless-cloning-using-opencv-python-cpp

@defgroup photo_render Non-Photorealistic Rendering

Useful links:

http://www.inf.ufrgs.br/~eslgastal/DomainTransform

https://www.learnopencv.com/non-photorealistic-rendering-using-opencv-python-c/

@defgroup photo_c C API

関数詳解

createAlignMTB()

CV_EXPORTS_W Ptr< AlignMTB > cv::createAlignMTB	(	int	max_bits = 6,
		int	exclude_range = 4,
		bool	cut = true
	)

Creates AlignMTB object

引数

max_bits	logarithm to the base 2 of maximal shift in each dimension. Values of 5 and 6 are usually good enough (31 and 63 pixels shift respectively).
exclude_range	range for exclusion bitmap that is constructed to suppress noise around the median value.
cut	if true cuts images, otherwise fills the new regions with zeros.

createCalibrateDebevec()

CV_EXPORTS_W Ptr< CalibrateDebevec > cv::createCalibrateDebevec	(	int	samples = 70,
		float	lambda = 10.0f,
		bool	random = false
	)

Creates CalibrateDebevec object

引数

samples	number of pixel locations to use
lambda	smoothness term weight. Greater values produce smoother results, but can alter the response.
random	if true sample pixel locations are chosen at random, otherwise they form a rectangular grid.

createCalibrateRobertson()

CV_EXPORTS_W Ptr< CalibrateRobertson > cv::createCalibrateRobertson	(	int	max_iter = 30,
		float	threshold = 0.01f
	)

Creates CalibrateRobertson object

引数

max_iter	maximal number of Gauss-Seidel solver iterations.
threshold	target difference between results of two successive steps of the minimization.

createMergeMertens()

CV_EXPORTS_W Ptr< MergeMertens > cv::createMergeMertens	(	float	contrast_weight = 1.0f,
		float	saturation_weight = 1.0f,
		float	exposure_weight = 0.0f
	)

Creates MergeMertens object

引数

contrast_weight	contrast measure weight. See MergeMertens.
saturation_weight	saturation measure weight
exposure_weight	well-exposedness measure weight

createTonemap()

CV_EXPORTS_W Ptr< Tonemap > cv::createTonemap

(

float

gamma = 1.0f

)

Creates simple linear mapper with gamma correction

引数

gamma

positive value for gamma correction. Gamma value of 1.0 implies no correction, gamma equal to 2.2f is suitable for most displays. Generally gamma > 1 brightens the image and gamma < 1 darkens it.

createTonemapDrago()

CV_EXPORTS_W Ptr< TonemapDrago > cv::createTonemapDrago	(	float	gamma = 1.0f,
		float	saturation = 1.0f,
		float	bias = 0.85f
	)

Creates TonemapDrago object

引数

gamma	gamma value for gamma correction. See createTonemap
saturation	positive saturation enhancement value. 1.0 preserves saturation, values greater than 1 increase saturation and values less than 1 decrease it.
bias	value for bias function in [0, 1] range. Values from 0.7 to 0.9 usually give best results, default value is 0.85.

createTonemapMantiuk()

CV_EXPORTS_W Ptr< TonemapMantiuk > cv::createTonemapMantiuk	(	float	gamma = 1.0f,
		float	scale = 0.7f,
		float	saturation = 1.0f
	)

Creates TonemapMantiuk object

引数

gamma	gamma value for gamma correction. See createTonemap
scale	contrast scale factor. HVS response is multiplied by this parameter, thus compressing dynamic range. Values from 0.6 to 0.9 produce best results.
saturation	saturation enhancement value. See createTonemapDrago

createTonemapReinhard()

CV_EXPORTS_W Ptr< TonemapReinhard > cv::createTonemapReinhard	(	float	gamma = 1.0f,
		float	intensity = 0.0f,
		float	light_adapt = 1.0f,
		float	color_adapt = 0.0f
	)

Creates TonemapReinhard object

引数

gamma	gamma value for gamma correction. See createTonemap
intensity	result intensity in [-8, 8] range. Greater intensity produces brighter results.
light_adapt	light adaptation in [0, 1] range. If 1 adaptation is based only on pixel value, if 0 it's global, otherwise it's a weighted mean of this two cases.
color_adapt	chromatic adaptation in [0, 1] range. If 1 channels are treated independently, if 0 adaptation level is the same for each channel.