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function LM2OpenCV(database, HOMEIMAGES, base_folder, num_neg, patch_size)
% LM2OpenCV Outputs query in OpenCV Haar-detector format.
% LM2OpenCV(database, HOMEIMAGES, base_folder, num_neg, patch_size)
% converts and stores the object images specified by the LabelMe database
% struct to the OpenCV haar-detector format. base_folder specifies the
% target directory for which positive and negative training examples are
% stored for input to the OpenCV haar-detector training utility
% (createsamples.exe and haartraining.exe).
%
% To form positive training examples, object images are copied from the
% LabelMe database into the folder base_folder/positives and the file
% positives.txt is created and stored in base_folder. The positives.txt
% file lists for each image in database the object bounding boxes and is
% provided as input to the OpenCV createsamples routine.
%
% The negative examples are generated by taking num_neg subwindows of
% size patch_size=[width height] from the images in database that do not
% contain an object instance. These windows are sampled at random
% locations in the images. The cropped subwindows are stored in the
% directory base_folder/negatives and the file negatives.txt is created
% and stored in base_folder, which lists the image filenames stored in
% the negatives directory. The negatives.txt file is used by the OpenCV
% haartraining routine.
%
% The variable HOMEIMAGES specifies the physical location of the LabelMe
% database used by the database index database.
%
% To understand how to train an OpenCV haar-detector with the training
% samples and files generated by this script use example command line
% calls are provided below.
%
% Example (Pedestrian Detector):
%
% (In MATLAB)
%
% HOMEIMAGES = 'C:/LabelMe/Images';
% HOMEANNOTATIONS = 'C:/LabelMe/Annotations';
% base_folder = 'D:/dtd';
% num_neg = 10000;
% patch_size = [16 32]; % width=16, height=32
%
% LMdb = LMdatabase(HOMEANNOTATIONS);
% query = 'pedestrian,person,human,man,woman';
% database = LMquery(LMdb, 'object.name', query);
% LM2OpenCV(database, HOMEIMAGES, base_folder, num_neg, patch_size);
% counts = LMcountobject(database, query);
%
% (Command Prompt, Let counts=900)
%
% createsamples -info D:\dtd\positive.txt -vec D:\dtd\positives.vec
% -num 900 -w 16 -h 32
%
% haartraining -data D:\dtd\peddetector\ -vec D:\dtd\positives.vec -bg
% D:\dtd\negatives.txt -npos 900 -nneg 10000 -w 16 -h 32
%
% In the above example, the call to createsamples generates the file
% positives.vec used by the haartraining routine. The haartraining
% routine then creates the OpenCV Haar pedestrian detector and saves it
% in the director 'D:\dtd\peddetector'.
%
% get number of images in the database
Nimages = length(database);
% sample negatives evenly from each image
nneg_per_image = ceil(num_neg/Nimages);
if(nneg_per_image<1)
nneg_per_image = 1;
end
% create directories positives and negatives
pos_res = mkdir(base_folder, 'positives');
neg_res = mkdir(base_folder, 'negatives');
if ~(pos_res & neg_res)
error('LM2OpenCV error: Unable to create positives and/or negatives directories.');
end
% create files positives.txt and negatives.txt
pbdir = sprintf('%s/positives',base_folder);
nbdir = sprintf('%s/negatives',base_folder);
pfilename = sprintf('%s/positives.txt', base_folder);
nfilename = sprintf('%s/negatives.txt', base_folder);
pos_file = fopen(pfilename, 'w+t');
neg_file = fopen(nfilename, 'w+t');
if (pos_file<0 || neg_file<0)
error('LM2OpenCV error: Unable to create files positive.txt and/or negatives.txt.');
end
% traverse images:
% - copy over positive image files to the positives directory
% - crop negative examples and store in negatives directory
% - create files positives.txt and negatives.txt
neg_ctr = 0;
obj_ctr = 0;
pw = patch_size(1);
ph = patch_size(2);
for i = 1:Nimages
if isfield(database(i).annotation, 'object')
Nobjects = length(database(i).annotation.object);
try
% load image
img = LMimread(database, i, HOMEIMAGES); % Load image
[nrows ncols c] = size(img);
if (c==3) % convert to grayscale? (I'm not sure if this is required by OpenCV...)
img = rgb2gray(img);
end;
% crop and add positive examples from image i to positive image
% directory
bboxes = []; % store bounding boxes for negative patch generation
for j = 1:Nobjects
[X,Y] = getLMpolygon(database(i).annotation.object(j).polygon);
% compute bounding box of object
x = min(X)-2;
y = min(Y)-2;
w = max(X)+2 - x;
h = max(Y)+2 - y;
ctr_x = x+w/2;
ctr_y = y+h/2;
% round width and height to be a multiple of the patch size
% width and height, and re-center bounding box
sfactor = max(w/pw,h/ph);
w = floor(sfactor*pw);
h = floor(sfactor*ph);
x = floor(ctr_x - w/2);
y = floor(ctr_y - h/2);
% make sure that patch fits inside image (otherwise skip
% this positive)
if (w>ncols || h>nrows)
continue;
end
% check boundaries
if(x<1); x = 1; end;
if(y<1); y = 1; end;
if((x+w)>ncols); x = ncols-w; end;
if((y+h)>nrows); y = nrows-h; end;
% crop and save image in positive image directory
img_filename = sprintf('%s/pos%06d.jpg', pbdir, obj_ctr);
cimg = img(y:(y+h-1),x:(x+w-1));
imwrite(cimg, img_filename, 'JPG', 'Quality', 100);
% add entry into positives file:
% OpenCV format is upper-left corner (x,y), width (w) and
% height (h)
fprintf(pos_file, 'positives\\pos%06d.jpg\t1\t0 0 %d %d\n', obj_ctr, w, h);
% use bboxes below...
bboxes = [bboxes; x y w h];
% next object
obj_ctr = obj_ctr + 1;
end
% generate negative patches
x = [];
y = [];
for j = 1:nneg_per_image
if neg_ctr > num_neg
break;
end
cx = floor(rand(1)*(ncols-pw-1));
cy = floor(rand(1)*(nrows-ph-1));
% check boundaries
if(cx<1); cx = 1; end;
if(cy<1); cy = 1; end;
if((cx+pw)>ncols); cx = ncols-pw; end;
if((cy+ph)>nrows); cy = nrows-ph; end;
while (sum(cx==x) || sum(cy==y) || ...
isOverlap(cx,cy,pw,ph,bboxes))
cx = floor(rand(1)*(ncols-pw-1));
cy = floor(rand(1)*(nrows-ph-1));
% check boundaries
if(cx<1); cx = 1; end;
if(cy<1); cy = 1; end;
if((cx+pw)>ncols); cx = ncols-pw; end;
if((cy+ph)>nrows); cy = nrows-ph; end;
end
x = [x cx];
y = [y cy];
% crop and save negative patch
cimg = img(cy:(cy+ph-1),cx:(cx+pw-1));
img_filename = sprintf('%s/neg%06d.jpg', nbdir, neg_ctr);
imwrite(cimg, img_filename, 'JPG', 'Quality', 100);
% update negatives file
fprintf(neg_file, 'negatives\\neg%06d.jpg\n', neg_ctr);
neg_ctr = neg_ctr + 1;
end
catch
i
'dimensions (x, y, w, h)'
x
y
w
h
end
end
end
% done.
fclose(pos_file);
fclose(neg_file);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% isOverlap
%
function ans = isOverlap(x, y, w, h, bboxes)
ans = 0;
n = size(bboxes,1);
for idx = 1:n
cx = bboxes(idx,1);
cy = bboxes(idx,2);
cw = bboxes(idx,3);
ch = bboxes(idx,4);
if ~(x>(cx+cw) || y>(cy+ch) || (x+w)<cx || (y+h)<cy)
ans = 1;
return;
end
end