SourceXtractorPlusPlus  0.15
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SimpleBackgroundAnalyzer.cpp
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1 
17 /*
18  * Background.cpp
19  *
20  * Created on: Oct 11, 2016
21  * Author: mschefer
22  */
23 
27 
28 #include <memory>
29 #include <algorithm>
30 
34 
35 
36 namespace SourceXtractor {
37 
41  WeightImage::PixelType /*variance_threshold*/) const {
42 
43  // FIXME we use a VectorImage the same size as input which won't allow larger than memory images to be processed
44 
45  auto image_copy = VectorImage<DetectionImage::PixelType>::create(*image);
46  std::sort(image_copy->getData().begin(), image_copy->getData().end());
47  bck_model_logger.debug() << "Using the SimpleBackgroundLeverAnalyzer";
48 
49  auto background_level = image_copy->getData()[image_copy->getData().size()/2]; // the median
50  auto background_level_map = ConstantImage<SeFloat>::create(image->getWidth(), image->getHeight(), background_level);
51 
52  auto subtracted_image = SubtractImage<SeFloat>::create(image, background_level_map);
53 
54  auto background_variance = getVariance(subtracted_image);
55  auto background_variance_map = ConstantImage<SeFloat>::create(image->getWidth(), image->getHeight(), background_variance);
56  bck_model_logger.debug() << "bg: " << background_level << " var: " << background_variance;
57 
58  return BackgroundModel(background_level_map, background_variance_map, 1.0, std::sqrt(background_variance));
59 }
60 
61 
63  // Note: We compute the RMS by only taking into consideration pixels
64  // below the background value.
66  Accessor accessor(image, Accessor::TOP_LEFT, 256, 1);
67 
68  double variance = 0;
69  int pixels = 0;
70  for (int y = 0; y < accessor.getHeight(); y++) {
71  for (int x = 0; x < accessor.getWidth(); x++) {
72  auto value = accessor.getValue(x, y);
73  if (value < 0) {
74  variance += value * value;
75  pixels++;
76  }
77  }
78  }
79 
80  if (pixels > 0) {
81  variance /= pixels;
82  }
83 
84  return variance;
85 }
86 
87 }
88 
BackgroundModel analyzeBackground(std::shared_ptr< DetectionImage > image, std::shared_ptr< WeightImage > variance_map, std::shared_ptr< Image< unsigned char >> mask, WeightImage::PixelType variance_threshold) const override
static Elements::Logging bck_model_logger
Definition: Utils.h:25
std::shared_ptr< DependentParameter< std::shared_ptr< EngineParameter > > > x
SeFloat32 SeFloat
Definition: Types.h:32
static std::shared_ptr< VectorImage< T > > create(Args &&...args)
Definition: VectorImage.h:100
static SeFloat getVariance(std::shared_ptr< DetectionImage > image)
void debug(const std::string &logMessage)
std::shared_ptr< DependentParameter< std::shared_ptr< EngineParameter > > > y
static std::shared_ptr< ConstantImage< T > > create(int width, int height, T constant_value)
Definition: ConstantImage.h:42
Interface representing an image.
Definition: Image.h:43
T sort(T...args)
T sqrt(T...args)
static std::shared_ptr< ProcessedImage< T, P > > create(std::shared_ptr< const Image< T >> image_a, std::shared_ptr< const Image< T >> image_b)