写了一个输入图片，便会生成美观的图像各通道亮度分布图的函数，大概效果如下：
老样子，工具函数放在最前面，之后会介绍咋用这个函数：
工具函数
function HistogramPic(pic)
FreqNum=zeros(size(pic,3),256);
for i=1:size(pic,3)
for j=0:255
FreqNum(i,j+1)=sum(sum(pic(:,:,i)==j));
end
end
ax=gca;hold(ax,'on');box on;grid on
if size(FreqNum,1)==3
bar(0:255,FreqNum(1,:),'FaceColor',[0.6350 0.0780 0.1840],'FaceAlpha',0.5);
bar(0:255,FreqNum(2,:),'FaceColor',[0.2400 0.5300 0.0900],'FaceAlpha',0.5);
bar(0:255,FreqNum(3,:),'FaceColor',[0 0.4470 0.7410],'FaceAlpha',0.5);
ax.XLabel.String='RGB brightness';
rrange=[num2str(min(pic(:,:,1),[],[1,2])),' , ',num2str(max(pic(:,:,1),[],[1,2]))];
grange=[num2str(min(pic(:,:,2),[],[1,2])),' , ',num2str(max(pic(:,:,2),[],[1,2]))];
brange=[num2str(min(pic(:,:,3),[],[1,2])),' , ',num2str(max(pic(:,:,3),[],[1,2]))];
legend({['R: range[',rrange,']'],['G: range[',grange,']'],['B: range[',brange,']']},...
'Location','northwest','Color',[0.9412 0.9412 0.9412],...
'FontName','Cambria','LineWidth',0.8,'FontSize',11);
else
bar(0:255,FreqNum(1,:),'FaceColor',[0.50 0.50 0.50],'FaceAlpha',0.5);
ax.XLabel.String='Gray scale';
krange=[num2str(min(pic(:,:,1),[],[1,2])),' , ',num2str(max(pic(:,:,1),[],[1,2]))];
legend(['Gray: range[',krange,']'],...
'Location','northwest','Color',[0.9412 0.9412 0.9412],...
'FontName','Cambria','LineWidth',0.8,'FontSize',11);
end
ax.LineWidth=1;
ax.GridLineStyle='--';
ax.XLim=[-5 255];
ax.XTick=[0:45:255,255];
ax.YLabel.String='Frequency number';
ax.FontName='Cambria';
ax.FontSize=13;
end函数调用
非常简单的使用方法，就是读取图片后调用函数即可：
pic=imread('test.png');
HistogramPic(pic)若图像是彩图则效果如下：
若图像为灰度图则效果如下：
