faster-rcnn中utils下几个重要函数的解析

utils下的函数主要是为了整个工程调用的方便而设计的,这里讲解其中几个比较重要的函数。
1、boxoverlap.m
用来计算两个boxes中box间的重叠系数。元组o中的元素是矩阵，矩阵o{i}代表boxes a和box b(i)之间的交叉系数，size(o{i})=(m,1)。m–表示boxes a中有m个box。而size(o)=n。n–表示boxes b中有n个box，最后返回cell2mat(o)，size为(m,n)
这个函数主要在选择产生的roi时会用到，用于选择满足一定重叠系数的roi.

function o = boxoverlap(a, b)% Compute the symmetric intersection over union overlap between a set of% bounding boxes in a and a single bounding box in b.%% a  a matrix where each row specifies a bounding box% b  a matrix where each row specifies a bounding box-------------------------------------------------------o = cell(1, size(b, 1));for i = 1:size(b, 1)    x1 = max(a(:,1), b(i,1));%Create a matrix and return the largest value between each of its elements compared to a scalar.    y1 = max(a(:,2), b(i,2));    x2 = min(a(:,3), b(i,3));    y2 = min(a(:,4), b(i,4));    w = x2-x1+1;    h = y2-y1+1;    inter = w.*h;    aarea = (a(:,3)-a(:,1)+1) .* (a(:,4)-a(:,2)+1);    barea = (b(i,3)-b(i,1)+1) * (b(i,4)-b(i,2)+1);    % intersection over union overlap    o{i} = inter ./ (aarea+barea-inter);    % set invalid entries to 0 overlap    o{i}(w <= 0) = 0;    o{i}(h <= 0) = 0;endo = cell2mat(o);

2、im_list_to_blob.m
输入元组ims，ims{i}为一张图片,将ims转换为blob(w,h,3,n)

function blob = im_list_to_blob(ims)%ims--cell    max_shape = max(cell2mat(cellfun(@size, ims(:), 'UniformOutput', false)), [], 1);    assert(all(cellfun(@(x) size(x, 3), ims, 'UniformOutput', true) == 3));    num_images = length(ims);    blob = zeros(max_shape(1), max_shape(2), 3, num_images, 'single');    for i = 1:length(ims)        im = ims{i};        blob(1:size(im, 1), 1:size(im, 2), :, i) = im;     endend

3、
prep_im_for_blob.m 根据输入图片，图片均值，目标尺寸，返回目标图片和缩放系数。
prep_im_for_blob_size.m 按输入图片的尺寸和目标尺寸，返回尺寸缩放系数。

function [im, im_scale] = prep_im_for_blob(im, im_means, target_size, max_size)    im = single(im);    if ~isa(im, 'gpuArray')        try            im = bsxfun(@minus, im, im_means);        catch            im_means = imresize(im_means, [size(im, 1), size(im, 2)], 'bilinear', 'antialiasing', false);                im = bsxfun(@minus, im, im_means);        end        im_scale = prep_im_for_blob_size(size(im), target_size, max_size);        target_size = round([size(im, 1), size(im, 2)] * im_scale);        im = imresize(im, target_size, 'bilinear', 'antialiasing', false);    else        % for im as gpuArray        try            im = bsxfun(@minus, im, im_means);        catch            im_means_scale = max(double(size(im, 1)) / size(im_means, 1), double(size(im, 2)) / size(im_means, 2));            im_means = imresize(im_means, im_means_scale);                y_start = floor((size(im_means, 1) - size(im, 1)) / 2) + 1;            x_start = floor((size(im_means, 2) - size(im, 2)) / 2) + 1;            im_means = im_means(y_start:(y_start+size(im, 1)-1), x_start:(x_start+size(im, 2)-1));            im = bsxfun(@minus, im, im_means);        end        im_scale = prep_im_for_blob_size(size(im), target_size, max_size);        im = imresize(im, im_scale);    endendfunction im_scale = prep_im_for_blob_size(im_size, target_size, max_size)    im_size_min = min(im_size(1:2));    im_size_max = max(im_size(1:2));    im_scale = double(target_size) / im_size_min;    % Prevent the biggest axis from being more than MAX_SIZE    if round(im_scale * im_size_max) > max_size        im_scale = double(max_size) / double(im_size_max);    endend

4、
RectLTRB2LTWH
RectLTWH2LTRB
坐标标定的不同方式之间的转换。

function [ rectsLTWH ] = RectLTRB2LTWH( rectsLTRB )%rects (l, t, r, b) to (l, t, w, h)rectsLTWH = [rectsLTRB(:, 1), rectsLTRB(:, 2), rectsLTRB(:, 3)-rectsLTRB(:,1)+1, rectsLTRB(:,4)-rectsLTRB(:,2)+1];endfunction [ rectsLTRB ] = RectLTWH2LTRB(rectsLTWH)%rects (l, t, r, b) to (l, t, w, h)rectsLTRB = [rectsLTWH(:, 1), rectsLTWH(:, 2), rectsLTWH(:, 1)+rectsLTWH(:,3)-1, rectsLTWH(:,2)+rectsLTWH(:,4)-1];end

5、
输入一张图片,含多个box坐标信息的元组boxes,每个box对应的标签legends,对图片进行信息的标注。输出图片尺寸固定，要注意对应box坐标的缩放。

function showboxes(im, boxes, legends, color_conf)% Draw bounding boxes on top of an image.%   showboxes(im, boxes)%% -------------------------------------------------------fix_width = 800;if isa(im, 'gpuArray')    im = gather(im);endimsz = size(im);scale = fix_width / imsz(2);im = imresize(im, scale);if size(boxes{1}, 2) >= 5    boxes = cellfun(@(x) [x(:, 1:4) * scale, x(:, 5)], boxes, 'UniformOutput', false);else    boxes = cellfun(@(x) x(:, 1:4) * scale, boxes, 'UniformOutput', false);endif ~exist('color_conf', 'var')    color_conf = 'default';endimage(im); axis image;axis off;set(gcf, 'Color', 'white');valid_boxes = cellfun(@(x) ~isempty(x), boxes, 'UniformOutput', true);valid_boxes_num = sum(valid_boxes);%选择每个class进行box标注时对应的颜色if valid_boxes_num > 0    switch color_conf        case 'default'            colors_candidate = colormap('hsv');            colors_candidate = colors_candidate(1:(floor(size(colors_candidate, 1)/valid_boxes_num)):end, :);            colors_candidate = mat2cell(colors_candidate, ones(size(colors_candidate, 1), 1))';            colors = cell(size(valid_boxes));            colors(valid_boxes) = colors_candidate(1:sum(valid_boxes));        case 'voc'            colors_candidate = colormap('hsv');            colors_candidate = colors_candidate(1:(floor(size(colors_candidate, 1)/20)):end, :);            colors_candidate = mat2cell(colors_candidate, ones(size(colors_candidate, 1), 1))';            colors = colors_candidate;    end    for i = 1:length(boxes)        if isempty(boxes{i})            continue;        end        for j = 1:size(boxes{i})            box = boxes{i}(j, 1:4);            if size(boxes{i}, 2) >= 5                score = boxes{i}(j, end);                linewidth = 2 + min(max(score, 0), 1) * 2;                rectangle('Position', RectLTRB2LTWH(box), 'LineWidth', linewidth, 'EdgeColor', colors{i});                label = sprintf('%s : %.3f', legends{i}, score);                text(double(box(1))+2, double(box(2)), label, 'BackgroundColor', 'w');            else                linewidth = 2;                rectangle('Position', RectLTRB2LTWH(box), 'LineWidth', linewidth, 'EdgeColor', colors{i});                label = sprintf('%s(%d)', legends{i}, i);                text(double(box(1))+2, double(box(2)), label, 'BackgroundColor', 'w');            end        end    endendend

6、

function tic_toc_print(fmt, varargin)% Print only after 1 second has passed since the last print. % Arguments are the same as for fprintf.% -------------------------------------------------------persistent th;if isempty(th)  th = tic();endif toc(th) > 1  fprintf(fmt, varargin{:});  drawnow;  th = tic();end