sift matlab.docVIP

function?[?SIFTFeatureVector,?locationX,?locationY?]?=?DenseSIFT(?image,?nPatchSize,?nGridSpacing?)?? ?? image?=?double(?image?);?? image?=?mean(?image,?3?);?? image?=?image?/?max(?image(?:?)?);?? ?? %?parameters?? nAngleNums?=?8;?? nBinNums?=?4;?? nSampleNums?=?nBinNums?*?nBinNums;?? alpha?=?9;?%%?parameter?for?attenuation?of?angles?(must?be?odd)?? ?? if?nargin??5?? ????sigmaGuassian?=?1;?? end?? ?? angleStep?=?2?*?pi?/?nAngleNums;?? angles?=?0?:?angleStep?:?2?*?pi;?? angles(?nAngleNums?+?1?)?=?[?];?%?bin?centers?? ?? [?nRow?nCol?]?=?size(?image?);?? ?? [?gaussianX,?gaussianY?]?=?genDeltaGaussian(?sigmaGuassian?);?? imageVerticalEdges?=?filter2(?gaussianX,?image,?same?);?%?vertical?edges?? imageHorizontalEdges?=?filter2(?gaussianY,?image,?same?);?%?horizontal?edges?? imageGradientMagnitude?=?sqrt(?imageVerticalEdges.^2?+?imageHorizontalEdges.^2?);?%?gradient?magnitude?? imageTheta?=?atan2(?imageHorizontalEdges,?imageVerticalEdges?);?? imageTheta(??isnan(?imageTheta?)??)?=?0;?%?replace?illegal?result?with?0?? ?? %?descriptor?locations?? locationX?=?nPatchSize?/?2?:?nGridSpacing?:?nCol?-?nPatchSize?/?2?+?1;?? locationY?=?nPatchSize?/?2?:?nGridSpacing?:?nRow?-?nPatchSize?/?2?+?1;?? ?? %?make?orientation?images?? imageOrientation?=?zeros(?[?nRow,?nCol,?nAngleNums?],?single?);?? ?? %?for?each?histogram?angle?? imageCos?=?cos(?imageTheta?);?? imageSin?=?sin(?imageTheta?);?? ?? for?index?=?1?:?nAngleNums?? ????%?compute?each?orientation?channel?? ????tmp?=?(?imageCos?*?cos(?angles(?index?)?)?+?imageSin?*?sin(?angles(?index?)?)?).^?alpha;?? ????tmp?=?tmp?.*?(?tmp??0?);?? ?????? ????%?weight?by?magnitude?? ????imageOrientation(?:,?:,?index?)?=?tmp?.*?imageGradientMagnitude;?? end?? ?? %?Convolution?formulation:?? nHalfPatchSize?=?nPatchSize?/?2;?? nHalfPatchSizeMinusDotFive?=?nHalfPatchSize?-?0.5;?? sampleResolution?=?nPatchSize?/?nBinNums;?? weightX?=?abs(?(?1?:?nPatchSize?)?-?nHalfPatchSizeMinusDotFive?)?/?sampleResolution;?? weightX?=?(?1?-?weightX?)?.*?(?weightX?=?1?);