--- a +++ b/combinedDeepLearningActiveContour/functions/intersampleIMAGES.m @@ -0,0 +1,65 @@ +% sampleIMAGES.m +% sampling patches for learning +function patches = sampleIMAGES(numpatches) +% sampleIMAGES +% Returns 10000 patches for training +load IMAGES; % load images from disk +patchsize = 8; % we'll use 8x8 patches +%numpatches = 10000; +% Initialize patches with zeros. Your code will fill in this matrix--one +% column per patch, 10000 columns. +patches = zeros(patchsize*patchsize, numpatches); + +%% ---------- YOUR CODE HERE -------------------------------------- +% Instructions: Fill in the variable called "patches" using data +% from IMAGES. +% +% IMAGES is a 3D array containing 10 images +% For instance, IMAGES(:,:,6) is a 512x512 array containing the 6th image, +% and you can type "imagesc(IMAGES(:,:,6)), colormap gray;" to visualize +% it. (The contrast on these images look a bit off because they have +% been preprocessed using using "whitening." See the lecture notes for +% more details.) As a second example, IMAGES(21:30,21:30,1) is an image +% patch corresponding to the pixels in the block (21,21) to (30,30) of +% Image 1 + +counter = 1; +ranimg = ceil(rand(1, numpatches) * 10); +ranpix = ceil(rand(2, numpatches) * (512 - patchsize)); +ranpixm = ranpix + patchsize - 1; +while(counter <= numpatches) +whichimg = ranimg(1, counter); +whichpix = ranpix(:, counter); +whichpixm = ranpixm(:, counter); +patch = IMAGES(whichpix(1):whichpixm(1), whichpix(2):whichpixm(2), whichimg); +repatch = reshape(patch, patchsize * patchsize, 1); +patches(:, counter) = repatch; +counter = counter + 1; +end + +%% --------------------------------------------------------------- +% For the autoencoder to work well we need to normalize the data +% Specifically, since the output of the network is bounded between [0,1] +% (due to the sigmoid activation function), we have to make sure +% the range of pixel values is also bounded between [0,1] +patches = normalizeData(patches); + +end + +%% --------------------------------------------------------------- +function patches = normalizeData(patches) + +% Squash data to [0.1, 0.9] since we use sigmoid as the activation +% function in the output layer + +% Remove DC (mean of images). +patches = bsxfun(@minus, patches, mean(patches)); + +% Truncate to +/-3 standard deviations and scale to -1 to 1 +pstd = 3 * std(patches(:)); +patches = max(min(patches, pstd), -pstd) / pstd; + +% Rescale from [-1,1] to [0.1,0.9] +patches = (patches + 1) * 0.4 + 0.1; + +end \ No newline at end of file