时间:2022-03-28 08:40:36 | 栏目:Python代码 | 点击:次
给你一张图片,如何提取里面曲线的数据,从而利用这些数据进行图像重绘、加工处理、测距、拟合得到函数表达式等操作呢?
前段时间,有个朋友问了我一个问题,大概意思就是要给图像的流线测距离,在我的印象里面,MATLAB 是似乎没有这种直接的功能的。
那么换个角度来理解一下这个问题,如果给你一张图像,如何提取里面点的数据?其实,有了曲线的数据,后面想干嘛就干嘛了。
一直没空弄这个,今天偷闲,安排!!!
以下面的图像作为例子。
我们先导入图像,进行简单的裁剪。为什么要裁剪呢?其实不裁剪也没关系,因为我后面是基于像素点的颜色来提取的曲线。如果你想提取的曲线不能通过颜色区分,那么,最好通过裁剪,把你不想要的部分尽可能地剪掉。
%% 读入图片,展示,有必要的话可以适当做一些裁剪 A = imread('a.jpg');%读取到一张图片 imshow(A); A = imcrop(A);%使用鼠标裁剪一波 imshow(A); [low_num,col_num,~] = size(A);
观察图像发现,我们要提取的曲线是蓝色的,所以我希望通过颜色把它区分出来。那么我们就要知道这个曲线的 RGB 值。我希望通过鼠标点选的方式获取到颜色值。
这里我偷个懒,直接采用了 slandarer 开源的颜色提取工具。这个模块不是我写的,特此声明,请尊重原创。
%% 颜色提取 getcolor(); color = color_list_temp(1,:);
function getcolor global control; global ima; global GUI; global x_limit; global y_limit; global color; global a; global color_number; global color_list; global page; global total_page; global color_list_temp; color=[]; page=1; total_page=2; color_list=[0 0 0]; color_list(1,:)=[]; color_number=1; rgb_type=1; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GUI.fig=figure('units','pixels',... 'position',[350 100 800 500],... 'Numbertitle','off',... 'menubar','none',... 'resize','off',... 'name','getcolor',... 'color',[0.95 0.95 0.95]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% uh1=uimenu('label','设置'); uimenu(uh1,'label','RGB类型设置','callback',@RGBset) function RGBset(~,~) GUI.rgbfig=figure('units','pixels',... 'position',[360 370 180 200],... 'Numbertitle','off',... 'menubar','none',... 'name','RGBset',... 'resize','off'); GUI.axes=axes('Units','pixels',... 'parent',GUI.rgbfig,... 'PlotBoxAspectRatio',[1 1 1],... 'Color',[0.95 0.95 0.95],... 'Box','on', ... 'XLim',[0 500],... 'YLim',[0 500], ... 'XColor',[0.95 0.95 0.95],... 'YColor',[0.95 0.95 0.95],... 'YDir','reverse', ... 'xtick',[],'ytick',[]); GUI.checkbox1=uicontrol('parent',GUI.rgbfig,... 'style','checkbox',... 'string','范围:0-1',... 'position',[45 150 400 30],... 'fontsize',10,... 'value',rgb_type,... 'callback',@ifon1); GUI.checkbox255=uicontrol('parent',GUI.rgbfig,... 'style','checkbox',... 'string','范围:0-255',... 'position',[45 120 400 30],... 'fontsize',10,... 'value',~rgb_type,... 'callback',@ifon255); GUI.makesurebutton=uicontrol('parent',GUI.rgbfig,... 'style','pushbutton',... 'string','确定设置',... 'position',[45 70 100 25],... 'fontsize',10,... 'callback',@settype); function ifon1(~,~) if(get(GUI.checkbox1,'value')==1) set(GUI.checkbox1,'value',1); set(GUI.checkbox255,'value',0); else set(GUI.checkbox1,'value',1); end end function ifon255(~,~) if(get(GUI.checkbox255,'value')==1) set(GUI.checkbox255,'value',1); set(GUI.checkbox1,'value',0); else set(GUI.checkbox255,'value',1); end end function settype(~,~) rgb_type=get(GUI.checkbox1,'value'); if ~isempty(color) set(GUI.text2,'string',['[',num2str((color/255).*rgb_type+color.*(~rgb_type)),']']); end show_color(page); close(GUI.rgbfig) end end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% uh2=uimenu('label','保存'); uimenu(uh2,'label','储存为mat','callback',@saveas_mat) uimenu(uh2,'label','储存为txt','callback',@saveas_txt) uimenu(uh2,'label','储存为excel','callback',@saveas_exl) uimenupic=uimenu(uh2,'label','储存为对照图'); uimenu(uimenupic,'label','储存全部页码','callback',@saveas_pic_all); uimenu(uimenupic,'label','储存当前页码','callback',@saveas_pic_now); function saveas_mat(~,~) try [filename, pathname] = uiputfile({'*.mat','mat'}); color_list_temp=(color_list/255).*rgb_type+color_list.*(~rgb_type); save([pathname,filename],'color_list_temp'); catch end end function saveas_txt(~,~) try [filename, pathname] = uiputfile({'*.txt','记事本'}); color_list_temp=(color_list/255).*rgb_type+color_list.*(~rgb_type); [m,n]=size(color_list_temp); fid=fopen([ pathname,filename],'w'); for ii=1:m for jj=1:n if jj==n fprintf(fid,'%d\r\n',color_list_temp(ii,jj)); else fprintf(fid,'%d\r\t',color_list_temp(ii,jj)); end end end fclose(fid); catch end end function saveas_exl(~,~) [filename, pathname] = uiputfile({'*.xlsx','记事本'}); color_list_temp=(color_list/255).*rgb_type+color_list.*(~rgb_type); xlswrite([ pathname,filename],color_list_temp) end function saveas_pic_all(~,~) page_with_color=total_page-1; px=50; gap_px=10; pic=ones(9*px,page_with_color*px+(page_with_color-1)*gap_px,3); for p=1:page_with_color for ii=(p-1)*9+1:p*9 for kk=1:3 if ii<=length(color_list) pic((ii-(p-1)*9-1)*px+1:(ii-(p-1)*9)*px,(p-1)*(px+gap_px)+1:(p-1)*(px+gap_px)+px,kk)=color_list(ii,kk)/255; end end end end [filename, pathname] = uiputfile({'*.jpg;*.png','All Image Files';... '*.jpg','JPG';'*.png','PNG' }); imwrite(pic,[pathname,filename]); end function saveas_pic_now(~,~) try [m,~]=size(color_list); m=m-(page-1)*9; m(m>9)=9; px=50; pic=ones(9*px,1*px,3); if m>0 for ii=(page-1)*9+1:(page-1)*9+m for kk=1:3 pic((ii-1)*px+1:ii*px,1:px,kk)=color_list(ii,kk)/255; end end else end [filename, pathname] = uiputfile({'*.jpg;*.png','All Image Files';... '*.jpg','JPG';'*.png','PNG' }); imwrite(pic,[pathname,filename]); catch end end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %uh3=uimenu('label','导入'); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GUI.text=uicontrol('parent',GUI.fig,... 'style','text',... 'string','色彩识别',... 'horizontalalign','center',... 'position',[50 440 400 30],... 'backgroundcolor',[0.85 0.89 0.85],... 'foregroundcolor','k',... 'fontsize',15); GUI.text1=uicontrol('parent',GUI.fig,... 'style','text',... 'string','',... 'horizontalalign','center',... 'position',[460 330 100 100],... 'backgroundcolor',[1 1 1],... 'foregroundcolor','k',... 'fontsize',10); GUI.text2=uicontrol('parent',GUI.fig,... 'style','text',... 'string','',... 'horizontalalign','center',... 'position',[350 440 210 30],... 'backgroundcolor',[1 1 1],... 'foregroundcolor','k',... 'fontsize',10); GUI.savecolorbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','储存颜色',... 'position',[460 290 100 30],... 'backgroundcolor',[0.85 0.89 0.85],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@save_color); GUI.deletedatabutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','清空数据',... 'position',[460 230 100 30],... 'backgroundcolor',[0.8 0.9 0.9],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@clear_data); GUI.deletepicbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','删除图片',... 'position',[460 180 100 30],... 'backgroundcolor',[0.8 0.9 0.9],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@delete_pic); GUI.getcapbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','屏幕截图',... 'position',[460 130 100 30],... 'backgroundcolor',[0.8 0.9 0.9],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@get_capture); GUI.getpicbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','读取图片',... 'position',[460 80 100 30],... 'backgroundcolor',[0.8 0.9 0.9],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@getImage); GUI.getcolorbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'tag','recc',... 'string','获取颜色',... 'position',[460 30 100 30],... 'backgroundcolor',[0.8 0.9 0.9],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@get_color); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% for i=1:9 GUI.text=uicontrol('parent',GUI.fig,... 'tag',num2str(i),... 'style','text',... 'string','',... 'horizontalalign','left',... 'position',[600 440-40*(i-1) 30 30],... 'backgroundcolor',[1 1 1],... 'foregroundcolor','k',... 'fontsize',10); end for i=1:9 GUI.text=uicontrol('parent',GUI.fig,... 'tag',[num2str(i),'t'],... 'style','text',... 'string','',... 'horizontalalign','center',... 'position',[640 440-40*(i-1) 150 30],... 'backgroundcolor',[1 1 1],... 'foregroundcolor','k',... 'fontsize',8); end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GUI.inputbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','清除最后一个颜色',... 'position',[600 80 190 30],... 'backgroundcolor',[0.85 0.89 0.85],... 'foregroundcolor','k',... 'fontsize',15,... 'callback',@delete_last); %GUI.inputbutton=uicontrol('parent',GUI.fig,... %'style','pushbutton',... %'string','导出数据',... %'position',[600 30 190 30],... %'backgroundcolor',[0.85 0.89 0.85],... %'foregroundcolor','k',... %'fontsize',15,... %'callback',@output_data); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GUI.lpbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','<上一页',... 'position',[600 30 70 30],... 'backgroundcolor',[0.85 0.85 0.85],... 'foregroundcolor','k',... 'fontsize',12,... 'callback',@lastpage); GUI.npbutton=uicontrol('parent',GUI.fig,... 'style','pushbutton',... 'string','下一页>',... 'position',[720 30 70 30],... 'backgroundcolor',[0.85 0.85 0.85],... 'foregroundcolor','k',... 'fontsize',12,... 'callback',@nextpage); GUI.page=uicontrol('parent',GUI.fig,... 'style','text',... 'string',[num2str(page),'/',num2str(total_page)],... 'horizontalalign','center',... 'position',[670 30 50 27],... 'backgroundcolor',[0.95 0.95 0.95],... 'foregroundcolor','k',... 'fontsize',12); function lastpage(~,~) page=page-1; page(page<1)=1; set(GUI.page,'string',[num2str(page),'/',num2str(total_page)]); show_color(page); end function nextpage(~,~) page=page+1; page(page>total_page)=total_page; set(GUI.page,'string',[num2str(page),'/',num2str(total_page)]); show_color(page); end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GUI.axes=axes('Units','pixels',... 'PlotBoxAspectRatio',[1 1 1],... 'Position',[50 30 400 400],... 'Color',[0.98 0.98 0.98],... 'Box','on', ... 'XLim',[0 500],... 'YLim',[0 500], ... 'XColor','w','YColor','w',... 'YDir','reverse', ... 'Tag','picbagaxes',... 'xtick',[],'ytick',[]); hold on; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %function output_data(~,~) %if color_number>1 %disp(color_list) %end %end function show_color(cur_page) len_list=size(color_list,1); for ii=(cur_page-1)*9+1:(cur_page-1)*9+9 if(ii<=len_list) set(findobj('tag',num2str(ii-(cur_page-1)*9)),'backgroundcolor',color_list(ii,:)/255) set(findobj('tag',[num2str(ii-(cur_page-1)*9),'t']),'string',['[',num2str((color_list(ii,:)/255).*rgb_type+color_list(ii,:).*(~rgb_type)),']']) else set(findobj('tag',num2str(ii-(cur_page-1)*9)),'backgroundcolor',[1 1 1]) set(findobj('tag',[num2str(ii-(cur_page-1)*9),'t']),'string','') end end end function save_color(~,~) if ~isempty(get(GUI.text2,'string')) %set(findobj('tag',num2str(color_number)),'backgroundcolor',color/255) %set(findobj('tag',[num2str(color_number),'t']),'string',['[',num2str((color/255).*rgb_type+color.*(~rgb_type)),']']) color_list(color_number,:)=color;%(color/255).*rgb_type+color.*(~rgb_type); color_number=color_number+1; if color_number-1>(total_page-1)*9 page=ceil(color_number/9); total_page=total_page+1; set(GUI.page,'string',[num2str(page),'/',num2str(total_page)]); end show_color(page) end end function delete_last(~,~) if color_number>=1 %set(findobj('tag',num2str(color_number-1)),'backgroundcolor',[1 1 1]) %set(findobj('tag',[num2str(color_number-1),'t']),'string','') color_list(end,:)=[]; color_number=color_number-1; if color_number-2<=(total_page-2)*9 page=ceil((color_number-1)/9); total_page=total_page-1; set(GUI.page,'string',[num2str(page),'/',num2str(total_page)]); end show_color(page) end end function delete_pic(~,~) control=0; set(findobj('Tag','picbagaxes'),... 'XLim',[0 500],... 'YLim',[0 500],... 'Position',[50 30 400 400],... 'Color',[0.98 0.98 0.98]); delete(a); end function clear_data(~,~) control=0; set(GUI.text1,'backgroundcolor',[1 1 1]); set(GUI.text2,'string',''); set(findobj('Tag','picbagaxes'),... 'XLim',[0 500],... 'YLim',[0 500],... 'Position',[50 30 400 400],... 'Color',[0.98 0.98 0.98]); set(findobj('tag','recc'),'string','获取颜色'); delete(a); end function get_color(~,~) if control==0 set(GUI.text1,'backgroundcolor',[1 1 1]); set(GUI.text2,'string',''); end control=1; set(gcf,'WindowButtonMotionFcn',@whilemovefcn) set(gcf,'WindowButtonDownFcn',@whileclickfcn) end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function whilemovefcn(~,~) xy=get(gca,'CurrentPoint'); x=xy(1,2);y=xy(1,1); if x<=x_limit&&y<=y_limit&&x>=0&&y>=0 x(x>x_limit)=x_limit; y(y>y_limit)=y_limit; x(x<1)=1; y(y<1)=1; x=round(x); y=round(y); if control==1 color=double([ima(x,y,1),ima(x,y,2),ima(x,y,3)]); set(GUI.text1,'backgroundcolor',color/255); set(GUI.text2,'string',['[',num2str((color/255).*rgb_type+color.*(~rgb_type)),']']); end else if control==1 set(GUI.text1,'backgroundcolor',[1 1 1]); set(GUI.text2,'string',''); end end end function whileclickfcn(~,~) xy=get(gca,'CurrentPoint'); x=xy(1,2);y=xy(1,1); if x<=x_limit&&y<=y_limit&&x>=0&&y>=0 control=0; set(GUI.text1,'backgroundcolor',color/255); set(GUI.text2,'string',['[',num2str((color/255).*rgb_type+color.*(~rgb_type)),']']); set(findobj('tag','recc'),'string','继续取色'); %disp(color/255) end end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function get_capture(~,~) screensize=get(0,'screensize'); screensize=1.5*screensize; robot=java.awt.Robot(); rectangle=java.awt.Rectangle(); rectangle.x=0; rectangle.y=0; rectangle.width=screensize(3); rectangle.height=screensize(4); image=robot.createScreenCapture(rectangle); data=image.getData(); temp=zeros(screensize(3)*screensize(4)*3,1); temp=data.getPixels(0,0,screensize(3),screensize(4),temp); temp=uint8(temp); R=temp(1:3:end); G=temp(2:3:end); B=temp(3:3:end); R=reshape(R,[screensize(3),screensize(4)]); G=reshape(G,[screensize(3),screensize(4)]); B=reshape(B,[screensize(3),screensize(4)]); R=R'; G=G'; B=B'; x_limit=screensize(4); y_limit=screensize(3); leng=max([x_limit,y_limit]); set(findobj('Tag','picbagaxes'),... 'XLim',[0 leng],... 'YLim',[0 leng]); ima=cat(3,R,G,B); delete(a); a=imshow(ima); end function getImage(~,~) warning off; try [filename, pathname] = uigetfile({'*.jpg;*.tif;*.png;*.gif','All Image Files';... '*.*','All Files' }); ima = imread([ pathname,filename]); [x,y,~]=size(ima); x_limit=x;y_limit=y; leng=max([x_limit,y_limit]); set(findobj('Tag','picbagaxes'),... 'XLim',[0 leng],... 'YLim',[0 leng]); delete(a); a=imshow(ima); catch end end end
用 RGB 比较颜色之间的相似度时,存在很大的问题,不建议直接使用,因为往往一个通道的一点改变,会导致最后融合在一起的颜色发生巨大变化,而如果三个通道的同时改变,却只会使最后的明暗发生变化,色调并不会产生巨大变化。而这也是H系列色彩空间普遍存在的问题。
所以,经过思考,我决定 RGB 的值转为 HSV 颜色空间,再进行色差计算。
色差计算,直接利用两个点的颜色在椎体上的欧式距离,即通过计算如下坐标点的欧式距离。我们通过编写 color_dist 函数计算。
%计算两个 HSV 颜色之间的距离 function d = color_dist(color_std,color) [x0,y0,z0] = getPos(color_std(1),color_std(2),color_std(3)); [x,y,z] = getPos(color(1),color(2),color(3)); d = sqrt((x-x0).^2+(y-y0).^2+(z-z0)^2); end function [x,y,z] = getPos(H,S,V) r = 1; h = sqrt(3); x = r*V*S*cos(H); y = r*V*S*sin(H); z = h*(1-V); end
%% 颜色转为 HSV,再进行色差计算 A2 = rgb2hsv(A); color2 = rgb2hsv(color); D = ones(low_num,col_num)*2; for i=1:low_num for j=1:col_num D(i,j) = color_dist(color2,A2(i,j,:)); end end mesh(D);
通过调节阈值参数,可以把我们想要的坐标轴过滤掉。阈值越小,过滤效果越明显。
%% 根据色彩,把想要的曲线分离出来 threshold = 0.5;%可以调整阈值使分离效果变好 I = (D<threshold); for i=1:3 RGB= A(:,:,i); RGB(~I)=255; A3(:,:,i) = RGB; end imshow(A3)
二值化图像是以矩阵形式存储的。我们根据色素点在矩阵中的位置,利用行列指标和坐标轴的标准化关系,提取数据,重建坐标系。
%% 二值化,提取数据 leftUp = [0,1];%标注截取的图片的左上角和右下角 rightDown = [1,0]; B = rgb2gray(A3); imshow(B); [pos_row,pow_col] = find(B~=255); Ps = [pos_row-1,pow_col-1]; Ps(:,1) = Ps(:,1)./(low_num-1); Ps(:,2) = Ps(:,2)./(col_num-1); x = (rightDown(1)-leftUp(1)).*Ps(:,2)+leftUp(1); y = leftUp(2)-abs(rightDown(2)-leftUp(2)).*Ps(:,1); scatter(x,y,0.38); X = [x,y];
看着八九不离十了,但是注意这里的坐标点是以散点的形式画出来的。是无序且没有区分度的,我们甚至无法使用plot
。
肉眼可见,这几条曲线是分隔开的。我们如何把这些数据按曲线分开且其上的点按顺序排好呢?我的做法是,使用鼠标选中你在意的曲线的一端,利用距离延拓法,还原整条曲线。
%% 数据分类与排序 N = size(X,1); gfrom = ginput(1); [~,minI] = min(sum((X - repmat(gfrom,N,1)).^2,2)); from = X(minI,:); X(minI,:) = []; X = [from;X]; tol = 0.01; X1 = findcurvepath(X,tol); plot(X1(:,1),X1(:,2))
其中用到了一个自己写函数 findcurvepath
,它可以从一个数据点出发,把所有的数据点按距离远近,像串珍珠一样串在一块。
function ps1 = findcurvepath(ps0,tol) %这个函数将点就近连接起来 ps1(1,1:2) = ps0(1,1:2);%将第一个取出来 ps0 = ps0(2:end,:);%ps0重置为剩下的部分 p = ps1(end,:);%p是取出来的最后一个 while ~isempty(ps0) i = 1; while 1 distances = p2psdistance(p,ps0); inds = find(distances == min(distances));%%%%%%%修复一个bug if length(inds) > 1 if size(ps1,1)<i+1 break; end p = ps1(end-i,:);%p是取出来的最后一个 i = i+1; else break; end end distances = p2psdistance(p,ps0); if min(distances)>tol break; end inds = find(distances == min(distances));%%%%%%%修复一个bug ind = inds(1); ps1(end+1,1:2) = ps0(ind,1:2); ps0(ind,:) = []; p = ps1(end,:); end end function distances = p2psdistance(p,ps) distances = sqrt((p(1)-ps(:,1)).^2+(p(2)-ps(:,2)).^2); end
我不喜欢做 GUI,因为乱七八糟的界面用起来确实令人心烦。另外一方面,不管是 GUI 或者说进一步的 exe 桌面程序,都依赖于 MATLAB 的环境。也就是说,你要运行代码,就必须先装 MATLAB 的环境。试想,一个安装过和简单用过 MATLAB 的人,都是有能力可以通过代码修改一些参数的,那么你做 GUI 不是画蛇添足么。