277 lines
9.6 KiB
C++
277 lines
9.6 KiB
C++
// Copyright (C) 2012 Davis E. King (davis@dlib.net)
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// License: Boost Software License See LICENSE.txt for the full license.
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#undef DLIB_FINE_HOG_IMaGE_ABSTRACT_Hh_
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#ifdef DLIB_FINE_HOG_IMaGE_ABSTRACT_Hh_
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#include "../array2d.h"
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#include "../matrix.h"
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#include "hog_abstract.h"
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namespace dlib
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{
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template <
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unsigned long cell_size_,
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unsigned long block_size_,
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unsigned long pixel_stride_,
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unsigned char num_orientation_bins_,
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int gradient_type_
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>
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class fine_hog_image : noncopyable
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{
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/*!
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REQUIREMENTS ON TEMPLATE PARAMETERS
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- cell_size_ > 1
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- block_size_ > 0
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- pixel_stride_ > 0
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- num_orientation_bins_ > 0
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- gradient_type_ == hog_signed_gradient or hog_unsigned_gradient
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INITIAL VALUE
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- size() == 0
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WHAT THIS OBJECT REPRESENTS
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This object is a version of the hog_image that allows you to extract HOG
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features at a finer resolution. The hog_image can only extract HOG features
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cell_size_ pixels apart. However, this object, the fine_hog_image can
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extract HOG features from every pixel location.
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The template arguments to this class have the same meaning as they do for
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the hog_image, except for pixel_stride_. This controls the stepping between
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HOG extraction locations. A value of 1 indicates HOG features should be
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extracted from every pixel location. A value of 2 indicates every other pixel
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location, etc.
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Finally, note that the interpolation used by this object is equivalent
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to using hog_angle_interpolation with hog_image.
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THREAD SAFETY
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Concurrent access to an instance of this object is not safe and should be protected
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by a mutex lock except for the case where you are copying the configuration
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(via copy_configuration()) of a fine_hog_image object to many other threads.
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In this case, it is safe to copy the configuration of a shared object so long
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as no other operations are performed on it.
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!*/
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public:
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const static unsigned long cell_size = cell_size_;
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const static unsigned long block_size = block_size_;
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const static unsigned long pixel_stride = pixel_stride_;
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const static unsigned long num_orientation_bins = num_orientation_bins_;
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const static int gradient_type = gradient_type_;
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const static long min_size = cell_size*block_size+2;
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typedef matrix<double, block_size*block_size*num_orientation_bins, 1> descriptor_type;
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fine_hog_image (
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);
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/*!
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ensures
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- this object is properly initialized
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!*/
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void clear (
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);
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/*!
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ensures
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- this object will have its initial value
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!*/
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void copy_configuration (
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const fine_hog_image&
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);
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/*!
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ensures
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- copies all the state information of item into *this, except for state
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information populated by load(). More precisely, given two fine_hog_image
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objects H1 and H2, the following sequence of instructions should always
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result in both of them having the exact same state.
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H2.copy_configuration(H1);
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H1.load(img);
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H2.load(img);
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!*/
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template <
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typename image_type
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>
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inline void load (
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const image_type& img
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);
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/*!
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requires
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- image_type is a dlib::matrix or something convertible to a matrix
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via mat()
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- pixel_traits<typename image_traits<image_type>::pixel_type>::has_alpha == false
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ensures
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- if (img.nr() < min_size || img.nc() < min_size) then
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- the image is too small so we don't compute anything on it
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- #size() == 0
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- else
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- generates a HOG image from the given image.
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- #size() > 0
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!*/
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inline void unload(
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);
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/*!
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ensures
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- #nr() == 0
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- #nc() == 0
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- clears only the state information which is populated by load(). For
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example, let H be a fine_hog_image object. Then consider the two
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sequences of instructions:
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Sequence 1:
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H.load(img);
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H.unload();
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H.load(img);
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Sequence 2:
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H.load(img);
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Both sequence 1 and sequence 2 should have the same effect on H.
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!*/
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inline unsigned long size (
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) const;
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/*!
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ensures
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- returns nr()*nc()
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!*/
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inline long nr (
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) const;
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/*!
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ensures
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- returns the number of rows in this HOG image
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!*/
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inline long nc (
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) const;
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/*!
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ensures
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- returns the number of columns in this HOG image
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!*/
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long get_num_dimensions (
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) const;
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/*!
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ensures
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- returns the number of dimensions in the feature vectors generated by
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this object.
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- In particular, returns the value block_size*block_size*num_orientation_bins
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!*/
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inline const descriptor_type& operator() (
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long row,
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long col
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) const;
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/*!
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requires
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- 0 <= row < nr()
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- 0 <= col < nc()
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ensures
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- returns the descriptor for the HOG block at the given row and column. This descriptor
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will include information from a window that is located at get_block_rect(row,col) in
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the original image given to load().
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- The returned descriptor vector will have get_num_dimensions() elements.
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!*/
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const rectangle get_block_rect (
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long row,
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long col
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) const;
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/*!
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ensures
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- returns a rectangle that tells you what part of the original image is associated
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with a particular HOG block. That is, what part of the input image is associated
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with (*this)(row,col).
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- The returned rectangle will be cell_size*block_size pixels wide and tall.
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!*/
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const point image_to_feat_space (
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const point& p
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) const;
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/*!
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ensures
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- Each local feature is extracted from a certain point in the input image.
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This function returns the identity of the local feature corresponding
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to the image location p. Or in other words, let P == image_to_feat_space(p),
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then (*this)(P.y(),P.x()) == the local feature closest to, or centered at,
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the point p in the input image. Note that some image points might not have
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corresponding feature locations. E.g. border points or points outside the
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image. In these cases the returned point will be outside get_rect(*this).
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!*/
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const rectangle image_to_feat_space (
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const rectangle& rect
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) const;
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/*!
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ensures
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- returns rectangle(image_to_feat_space(rect.tl_corner()), image_to_feat_space(rect.br_corner()));
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(i.e. maps a rectangle from image space to feature space)
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!*/
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const point feat_to_image_space (
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const point& p
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) const;
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/*!
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ensures
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- returns the location in the input image space corresponding to the center
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of the local feature at point p. In other words, this function computes
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the inverse of image_to_feat_space(). Note that it may only do so approximately,
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since more than one image location might correspond to the same local feature.
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That is, image_to_feat_space() might not be invertible so this function gives
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the closest possible result.
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!*/
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const rectangle feat_to_image_space (
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const rectangle& rect
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) const;
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/*!
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ensures
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- return rectangle(feat_to_image_space(rect.tl_corner()), feat_to_image_space(rect.br_corner()));
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(i.e. maps a rectangle from feature space to image space)
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!*/
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};
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// ----------------------------------------------------------------------------------------
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template <
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unsigned long T1,
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unsigned long T2,
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unsigned long T3,
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unsigned char T4,
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int T5
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>
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void serialize (
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const fine_hog_image<T1,T2,T3,T4,T5>& item,
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std::ostream& out
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);
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/*!
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provides serialization support
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!*/
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template <
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unsigned long T1,
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unsigned long T2,
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unsigned long T3,
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unsigned char T4,
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int T5
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>
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void deserialize (
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fine_hog_image<T1,T2,T3,T4,T5>& item,
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std::istream& in
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);
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/*!
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provides deserialization support
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!*/
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// ----------------------------------------------------------------------------------------
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}
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#endif // DLIB_FINE_HOG_IMaGE_ABSTRACT_Hh_
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