@ -3,114 +3,259 @@ HDR imaging
.. highlight :: cpp
makeHDR
-----------
Creates HDR image from a set of bracketed exposures using algorithm by Debevec and Malik.
This section describes high dynamic range imaging algorithms, namely tonemapping, exposure alignment, camera calibration with multiple exposures and exposure fusion.
"Recovering High Dynamic Range Radiance Maps from Photographs", Debevec, Malik, 1997
Tonemap
-------------
.. ocv:class :: Tonemap : public Algorithm
.. ocv:function :: void makeHDR(InputArrayOfArrays srcImgs, const std::vector<float>& expTimes, OutputArray dst, bool align = false)
:param src_imgs: vector of 8-bit 3-channel images
The base class for tonemapping algorithms - tools, that are used to map HDR image to 8-bit range.
Tonemap::process
-----------------------
Tonemaps image
.. ocv:function :: void Tonemap::process(InputArray src, OutputArray dst)
:param src: source image - 32-bit 3-channel Mat
:param dst: destination image - 32-bit 3-channel Mat with values in [0, 1] range
TonemapLinear
--------
.. ocv:class :: TonemapLinear : public Tonemap
Simple linear mapper with gamma correction.
createTonemapLinear
------------------
Creates TonemapLinear object
.. ocv:function :: Ptr<TonemapLinear> createTonemapLinear(float gamma = 1.0f);
:param gamma: gamma value for gamma correction
:param exp_times: exposure times for each of source images
:param dst: output image
:param align: if true, images are first aligned using median threshold bitmap algorithm. See :ocv:func:`getExpShift`.
tonemap
-----------
Tonemaps image.
TonemapDrago
--------
.. ocv:class :: TonemapDrago : public Tonemap
.. ocv:function :: tonemap(InputArray src, OutputArray dst, int algorithm, const std::vector<float>& params = std::vector<float>())
:param src: input HDR image
"Adaptive Logarithmic Mapping For Displaying HighContrast Scenes", Drago et al.
createTonemapDrago
------------------
Creates TonemapDrago object
.. ocv:function :: Ptr<TonemapDrago> createTonemapDrago(float gamma = 1.0f, float bias = 0.85f);
:param gamma: gamma value for gamma correction
:param dst: floating-point image in [0; 1] range
:param algorithm:
* TONEMAP_LINEAR - simple linear mapping
* TONEMAP_DRAGO - "Adaptive Logarithmic Mapping For Displaying HighContrast Scenes", Drago et al., 2003
* TONEMAP_REINHARD - "Dynamic Range Reduction Inspired by Photoreceptor Physiology", Reinhard, Devlin, 2005
* TONEMAP_DURAND - "Fast Bilateral Filtering for the Display of High-Dynamic-Range Images", Durand, Dorsey, 2002
:param params: vector of parameters for specified algorithm.
If some parameters are missing default values are used.
The first element is gamma value for gamma correction.
* TONEMAP_LINEAR:
No parameters.
* TONEMAP_DRAGO:
params[1] - value for bias function. Range [0.7, 0.9], default 0.85.
* TONEMAP_REINHARD:
params[1] - result intensity. Range [-8, 8], default 0.
params[2] - chromatic adaptation. Range [0, 1], default 0.
params[3] - light adaptation. Range [0, 1], default 0;
* TONEMAP_DURAND:
params[1] - result contrast on logarithmic scale.
params[2] - bilateral filter sigma in the color space.
params[3] - bilateral filter sigma in the coordinate space.
exposureFusion
-----------
Fuses a bracketed exposure sequence into a single image without converting to HDR first.
:param bias: value for bias function in [0, 1] range
TonemapDurand
--------
.. ocv:class :: TonemapDurand : public Tonemap
"Exposure Fusion", Mertens et al., 2007
"Fast Bilateral Filtering for the Display of High-Dynamic-Range Images", Durand, Dorsey, 2002
.. ocv:function :: exposureFusion(InputArrayOfArrays src_imgs, OutputArray dst, bool align = false, float wc = 1, float ws = 1, float we = 0)
:param src_imgs: vector of 8-bit 3-channel images
:param dst: output image. Although it's a floating-point image tonemapping is not necessary.
:param align: if true, images are first aligned using median threshold bitmap algorithm. See :ocv:func:`getExpShift`.
:param wc: contrast factor weight
:param ws: saturation factor weight
:param we: well-exposedness factor weight
getExpShift
-----------
Calculates translation vector that can be used to align img1 with img0.
Uses median threshold bitmap algorithm by Ward.
This implementation uses regular bilateral filter from opencv.
createTonemapDurand
------------------
Creates TonemapDurand object
.. ocv:function :: Ptr<TonemapDurand> createTonemapDurand(float gamma = 1.0f, float contrast = 4.0f, float sigma_space = 2.0f, float sigma_color = 2.0f);
:param gamma: gamma value for gamma correction
:param contrast: resulting contrast on logarithmic scale
:param sigma_space: filter sigma in the color space
:param sigma_color: filter sigma in the coordinate space
TonemapReinhardDevlin
--------
.. ocv:class :: TonemapReinhardDevlin : public Tonemap
"Dynamic Range Reduction Inspired by Photoreceptor Physiology", Reinhard, Devlin, 2005
createTonemapReinhardDevlin
------------------
Creates TonemapReinhardDevlin object
.. ocv:function :: Ptr<TonemapReinhardDevlin> createTonemapReinhardDevlin(float gamma = 1.0f, float intensity = 0.0f, float light_adapt = 1.0f, float color_adapt = 0.0f)
:param gamma: gamma value for gamma correction
:param intensity: result intensity. Range in [-8, 8] range
:param light_adapt: light adaptation in [0, 1] range. If 1 adaptation is based on pixel value, if 0 it's global
:param color_adapt: chromatic adaptation in [0, 1] range. If 1 channels are treated independently, if 0 adaptation level is the same for each channel
ExposureAlign
-------------
.. ocv:class :: ExposureAlign : public Algorithm
The base class for algorithms that align images of the same scene with different exposures
ExposureAlign::process
-----------------------
Aligns images
.. ocv:function :: void ExposureAlign::process(InputArrayOfArrays src, OutputArrayOfArrays dst, const std::vector<float>& times, InputArray response)
:param src: vector of input images
:param dst: vector of aligned images
:param times: vector of exposure time values for each image
:param response: matrix with camera response, one column per channel
AlignMTB
--------
.. ocv:class :: AlignMTB : public ExposureAlign
"Fast, Robust Image Registration for Compositing High Dynamic Range Photographs from Handheld Exposures", Ward, 2003
.. ocv:function :: getExpShift(InputArray img0, InputArray img1, int max_bits = 6, int exclude_range = 4)
This algorithm does not use exposure values and camera response, new image regions are filled with zeros.
AlignMTB::process
-----------------------
Short version of process, that doesn't take extra arguments.
.. ocv:function :: void AlignMTB::process(InputArrayOfArrays src, OutputArrayOfArrays dst)
:param src: vector of input images
:param img0: 8-bit 1-channel image
:param dst: vector of aligned images
AlignMTB::calculateShift
-----------------------
Calculates shift between two images.
.. ocv:function :: void AlignMTB::calculateShift(InputArray img0, InputArray img1, Point& shift)
:param img0: first image
:param img1: 8-bit 1-channel image
:param max_bits: logarithm to the base 2 of maximal shift in each dimension
:param exclude_range: range value for exclusion bitmap. Refer to the article.
shiftMat
-----------
Shifts image filling the new regions with zeros.
:param img1: second image
:param shift: how to shift the second image to correspond it with the first
.. ocv:function :: shiftMat(InputArray src, Point shift, OutputArray dst)
:param src: input image
AlignMTB::shiftMat
-----------------------
Gelper function, that shift Mat filling new regions with zeros.
.. ocv:function :: void AlignMTB::shiftMat(InputArray src, OutputArray dst, const Point shift)
:param src: input image
:param dst: result image
:param shift: shift value
createAlignMTB
------------------
Creates AlignMTB object
.. ocv:function :: Ptr<AlignMTB> createAlignMTB(int max_bits = 6, int exclude_range = 4)
:param max_bits: logarithm to the base 2 of maximal shift in each dimension
:param exclude_range: range for exclusion bitmap
ExposureCalibrate
-------------
.. ocv:class :: ExposureCalibrate : public Algorithm
The base class for camera response calibration algorithms.
ExposureCalibrate::process
-----------------------
Recovers camera response.
.. ocv:function :: void ExposureCalibrate::process(InputArrayOfArrays src, OutputArray dst, std::vector<float>& times)
:param src: vector of input images
:param dst: matrix with calculated camera response, one column per channel
:param times: vector of exposure time values for each image
CalibrateDebevec
--------
.. ocv:class :: CalibrateDebevec : public ExposureCalibrate
"Recovering High Dynamic Range Radiance Maps from Photographs", Debevec, Malik, 1997
createCalibrateDebevec
------------------
Creates CalibrateDebevec object
.. ocv:function :: Ptr<CalibrateDebevec> createCalibrateDebevec(int samples = 50, float lambda = 10.0f)
:param samples: number of pixel locations to use
:param lambda: smoothness term weight
ExposureMerge
-------------
.. ocv:class :: ExposureMerge : public Algorithm
The base class algorithms that can merge exposure sequence to a single image.
ExposureMerge::process
-----------------------
Merges images.
.. ocv:function :: void process(InputArrayOfArrays src, OutputArray dst, const std::vector<float>& times, InputArray response)
:param src: vector of input images
:param shift: shift vector
:param dst: result image
:param times: vector of exposure time values for each image
:param response: matrix with camera response, one column per channel
MergeDebevec
--------
.. ocv:class :: MergeDebevec : public ExposureMerge
"Recovering High Dynamic Range Radiance Maps from Photographs", Debevec, Malik, 1997
createMergeDebevec
------------------
Creates MergeDebevec object
.. ocv:function :: Ptr<MergeDebevec> createMergeDebevec();
MergeMertens
--------
.. ocv:class :: MergeMertens : public ExposureMerge
"Exposure Fusion", Mertens et al., 2007
The resulting image doesn't require tonemapping and can be converted to 8-bit image by multiplying by 255.
MergeMertens::process
-----------------------
Short version of process, that doesn't take extra arguments.
.. ocv:function :: void MergeMertens::process(InputArrayOfArrays src, OutputArray dst)
:param src: vector of input images
:param dst: output image
:param dst: result image
createMergeMertens
------------------
Creates MergeMertens object
.. ocv:function :: Ptr<MergeMertens> createMergeMertens(float contrast_weight = 1.0f, float saturation_weight = 1.0f, float exposure_weight = 0.0f)
:param contrast_weight: contrast factor weight
:param saturation_weight: saturation factor weight
:param exposure_weight: well-exposedness factor weight
Fedor Morozov
11 years ago