SIFT关键代码.docxVIP

有关SIFT函数的关键代码(2010-06-08 13:35:18) 转载标签：sift代码关键点杂谈分类：杂感function [ pos, scale, orient, desc ] = SIFT( im, octaves, intervals, object_mask, contrast_threshold, curvature_threshold, interactive )% [ pos, scale, orient, desc ] = SIFT( im, octaves, intervals, object_mask, contrast_threshold, curvature_threshold, interactive )if ~exist(octaves)?? octaves = 4;endif ~exist(intervals)?? intervals = 2;endif ~exist(object_mask)?? object_mask = ones(size(im));endif size(object_mask) ~= size(im)?? object_mask = ones(size(im));endif ~exist(contrast_threshold)?? contrast_threshold = 0.02;endif ~exist(curvature_threshold)?? curvature_threshold = 10.0;endif ~exist(interactive)?? interactive = 1;end% Check that the image is normalized to [0,1]if( (min(im(:)) 0) | (max(im(:)) 1) )?? fprintf( 2, Warning: image not normalized to [0,1].\n );end% Blur the image with a standard deviation of 0.5 to prevent aliasing% and then upsample the image by a factor of 2 using linear interpolation.% Lowe claims that this increases the number of stable keypoints by% a factor of 4.if interactive = 1?? fprintf( 2, Doubling image size for first octave...\n );endtic;antialias_sigma = 0.5;if antialias_sigma == 0?? signal = im;else?? g = gaussian_filter( antialias_sigma );%至少比0.5大?? if exist(corrsep) == 3??? signal = corrsep( g, g, im );?? else????? signal = conv2( g, g, im, same );?? endendsignal = im;[X Y] = meshgrid( 1:0.5:size(signal,2), 1:0.5:size(signal,1) );signal = interp2( signal, X, Y, *linear );??subsample = [0.5]; % subsampling rate for doubled image is 1/2if interactive = 1?? fprintf( 2, Prebluring image...\n );endpreblur_sigma = sqrt(sqrt(2)^2 - (2*antialias_sigma)^2);if preblur_sigma == 0?? gauss_pyr{1,1} = signal;else?? g = gaussian_filter( preblur_sigma );?? if exist(corrsep) == 3????? gauss_pyr{1,1} = corrsep( g, g, signal );?? else????? gauss_pyr{1,1} = conv2( g, g, signal, same );?? endendclear signalpre_time = toc;if interactive = 1?? fprintf( 2, Preprocessing time %.2f seconds.\n, pr