How can i vectorize the binning process for HOG feature computation and run on GPU ?
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Dear Friends,
I have been trying to implement the HOG feature calculation on matlab GPU (PCT toolbox). The code which i am using for it is provided in the link here : (<http://in.mathworks.com/matlabcentral/fileexchange/46408-histogram-of-oriented-gradients--hog--code-using-matlab)>.
In the above code, I was able to run on GPU up to the gradient computation which gave me a speed gain of 8x. But my GPU performance degraded drastically when i tried to implement the below part:
% Iterations for Blocks
for i = 0: rows/8 - 2 for j= 0: cols/8 -2
mag_patch = magnitude(8*i+1 : 8*i+16 , 8*j+1 : 8*j+16);
%mag_patch = imfilter(mag_patch,gauss);
ang_patch = angle(8*i+1 : 8*i+16 , 8*j+1 : 8*j+16);
block_feature=[];
%Iterations for cells in a block
for x= 0:1
for y= 0:1
angleA =ang_patch(8*x+1:8*x+8, 8*y+1:8*y+8);
magA =mag_patch(8*x+1:8*x+8, 8*y+1:8*y+8);
histr =zeros(1,9);
%Iterations for pixels in one cell
for p=1:8
for q=1:8
alpha= angleA(p,q);
% Binning Process (Bi-Linear Interpolation)
if alpha>10 && alpha<=30
histr(1)=histr(1)+ magA(p,q)*(30-alpha)/20;
histr(2)=histr(2)+ magA(p,q)*(alpha-10)/20;
elseif alpha>30 && alpha<=50
histr(2)=histr(2)+ magA(p,q)*(50-alpha)/20;
histr(3)=histr(3)+ magA(p,q)*(alpha-30)/20;
elseif alpha>50 && alpha<=70
histr(3)=histr(3)+ magA(p,q)*(70-alpha)/20;
histr(4)=histr(4)+ magA(p,q)*(alpha-50)/20;
elseif alpha>70 && alpha<=90
histr(4)=histr(4)+ magA(p,q)*(90-alpha)/20;
histr(5)=histr(5)+ magA(p,q)*(alpha-70)/20;
elseif alpha>90 && alpha<=110
histr(5)=histr(5)+ magA(p,q)*(110-alpha)/20;
histr(6)=histr(6)+ magA(p,q)*(alpha-90)/20;
elseif alpha>110 && alpha<=130
histr(6)=histr(6)+ magA(p,q)*(130-alpha)/20;
histr(7)=histr(7)+ magA(p,q)*(alpha-110)/20;
elseif alpha>130 && alpha<=150
histr(7)=histr(7)+ magA(p,q)*(150-alpha)/20;
histr(8)=histr(8)+ magA(p,q)*(alpha-130)/20;
elseif alpha>150 && alpha<=170
histr(8)=histr(8)+ magA(p,q)*(170-alpha)/20;
histr(9)=histr(9)+ magA(p,q)*(alpha-150)/20;
elseif alpha>=0 && alpha<=10
histr(1)=histr(1)+ magA(p,q)*(alpha+10)/20;
histr(9)=histr(9)+ magA(p,q)*(10-alpha)/20;
elseif alpha>170 && alpha<=180
histr(9)=histr(9)+ magA(p,q)*(190-alpha)/20;
histr(1)=histr(1)+ magA(p,q)*(alpha-170)/20;
end
toc;
end
end
block_feature=[block_feature histr]; % Concatenation of Four histograms to form one block feature
end
end
% Normalize the values in the block using L1-Norm
block_feature=block_feature/sqrt(norm(block_feature)^2+.01);
feature=[feature block_feature]; %Features concatenation
end
end
What all changes should i make to run this section. Please do help me in vectorizing this section and run the code on GPU. Any answer is welcome. Thank You.
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