如何给图像上已知坐标的点添加图例

Question

Imagesc图像中
已知某坐标，以及该坐标的值和对应的颜色
想在图像右上角做一个该点的图例，需要包括该点的颜色方块，颜色方块的右侧显示标签。
求问大shen们怎么做到,matlab或者python都可以

Answer 1

举例，获取第二行第三列点的图例：

x = [5 8];
y = [3 6];
C = [0 2 4 6; 8 10 12 14; 16 18 20 22];
scHdl=imagesc(x,y,C);
lgdHdl=getImagescLgdHdl(scHdl,2,3);
legend(lgdHdl,'2-3')


% 工具函数
function lgdHdl=getImagescLgdHdl(scHdl,row,col)
ax=gca;ax.XLim=ax.XLim;ax.YLim=ax.YLim;hold on
CData=scHdl.CData;
minC=min(CData,[],[1,2]);
maxC=max(CData,[],[1,2]);
CMap=colormap;
R=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,1),CData(row,col));
G=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,2),CData(row,col));
B=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,3),CData(row,col));
FaceColor=[R,G,B];
lgdHdl=fill(scHdl.XData(1)-2+[-1,-1,1,1],scHdl.XData(1)-2+[-1,1,1,-1],...
    FaceColor,'EdgeColor','none');
end

多个图例：

x = [5 8];
y = [3 6];
C = [0 2 4 6; 8 10 12 14; 16 18 20 22];
scHdl=imagesc(x,y,C);
lgdHdl1=getImagescLgdHdl(scHdl,2,3);
lgdHdl2=getImagescLgdHdl(scHdl,3,2);
legend([lgdHdl1,lgdHdl2],'2-3','3-2')


% 工具函数
function lgdHdl=getImagescLgdHdl(scHdl,row,col)
ax=gca;ax.XLim=ax.XLim;ax.YLim=ax.YLim;hold on
CData=scHdl.CData;
minC=min(CData,[],[1,2]);
maxC=max(CData,[],[1,2]);
CMap=colormap;
R=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,1),CData(row,col));
G=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,2),CData(row,col));
B=interp1(linspace(minC,maxC,size(CMap,1)),CMap(:,3),CData(row,col));
FaceColor=[R,G,B];
lgdHdl=fill(scHdl.XData(1)-2+[-1,-1,1,1],scHdl.XData(1)-2+[-1,1,1,-1],...
    FaceColor,'EdgeColor','none');
end