Contents

% Example generating the plots in Resolution Measured as Separability
% Compared to Full Width Half Maximum for Adaptive Beamformers
%
%
% If using some of this data or code you should cite:
% Rindal, O. M. H., Rodriguez-Molares, A., & Austeng, A. (2020). Resolution
% Measured as Separability Compared to Full Width Half Maximum for Adaptive
% Beamformers. IEEE International Ultrasonics Symposium, IUS, 1, 16–19.
%
% Abstract: Spatial resolution is defined as a system’s ability to separate
% targets using some kind of criterion, such as the Rayleigh criterion. However,
% in practice, lateral resolution is often evaluated by measuring the Full
% Width Half Maximum (FWHM at -6dB) of the point spread function (PSF).
% We hypothesize that FWHM overestimates the system resolution for some
% adaptive beamformers, compared to using the Rayleigh criterion.
% Simulation results seem to confirm this hypothesis.
%
% Author: Ole Marius Hoel Rindal <olemarius@olemarius.net>
% Date 24.11.2020

Run script to create beampatterns

create_beampatterns_plot

Load the data

clear all;
close all;

% data location
url='http://ustb.no/datasets/';       % if not found data will be downloaded from here
local_path = [data_path(), filesep];  % location of example data on this computer

filename = ['FieldII_CPWC_point_scatterers_res_v2.uff'];

% check if the file is available in the local path & downloads otherwise
tools.download(filename, url, local_path);


b_data_das = uff.beamformed_data();
b_data_cf = uff.beamformed_data();
b_data_pcf = uff.beamformed_data();
b_data_gcf = uff.beamformed_data();
b_data_mv = uff.beamformed_data();
b_data_ebmv = uff.beamformed_data();
b_data_dmas = uff.beamformed_data();

b_data_das.read([local_path,filesep,filename],'/b_data_das');
b_data_cf.read([local_path,filesep,filename],'/b_data_cf');
b_data_pcf.read([local_path,filesep,filename],'/b_data_pcf');
b_data_gcf.read([local_path,filesep,filename],'/b_data_gcf');
b_data_mv.read([local_path,filesep,filename],'/b_data_mv');
b_data_ebmv.read([local_path,filesep,filename],'/b_data_ebmv');
b_data_dmas.read([local_path,filesep,filename],'/b_data_dmas');

sca = b_data_das.scan;
% Separating distances used in the simulation. See
separating_distance = [4 2 1 0.5 0.44 0.4];

UFF: reading /b_data_das [uff.beamformed_data]
UFF: reading /b_data_cf [uff.beamformed_data]
UFF: reading /b_data_pcf [uff.beamformed_data]
UFF: reading /b_data_gcf [uff.beamformed_data]
UFF: reading /b_data_mv [uff.beamformed_data]
UFF: reading /b_data_ebmv [uff.beamformed_data]
UFF: reading /b_data_dmas [uff.beamformed_data]

Plot the images

b_data_das.plot([],'DAS');
b_data_cf.plot([],'CF');
b_data_pcf.plot([],'PCF');
b_data_gcf.plot([],'GCF');
b_data_mv.plot([],'MV');
b_data_ebmv.plot([],'EBMV');
b_data_dmas.plot([],'F-DMAS');

% Get images in separate variables
img{1} = b_data_das.get_image();
img{2} = b_data_cf.get_image();
img{3} = b_data_pcf.get_image();
img{4} = b_data_gcf.get_image();
img{5} = b_data_mv.get_image();
img{6} = b_data_ebmv.get_image();
img{7} = b_data_dmas.get_image();

tags{1} = 'DAS';
tags{2} = 'CF';
tags{3} = 'PCF';
tags{4} = 'GCF';
tags{5} = 'MV';
tags{6} = 'EBMV';
tags{7} = 'F-DMAS';

Plot resolution measured as FWHM

img_none{1} = b_data_das.get_image('none');
img_none{2} = b_data_cf.get_image('none');
img_none{3} = b_data_pcf.get_image('none');
img_none{4} = b_data_gcf.get_image('none');
img_none{5} = b_data_mv.get_image('none');
img_none{6} = b_data_ebmv.get_image('none');
img_none{7} = b_data_dmas.get_image('none');

f = figure(88);clf;
clear res;
for m = 1:7
    format long
    lateral =  img{m}(103,:,1);

    [res(m)] = calculate_6dB_resolution(sca.x_axis*10^3,lateral,1,88,m);

    ylim(gca,[-30 0])
    xlim(gca,[-1 1])
    set(gca,'FontSize',15);
end

subplot(2,7,[8:14]);
bar(1:7,res)
xlim([0.5 7.5])
ylabel('FWHM [mm]');
xticks(1:7)
xticklabels(tags)
set(gca,'FontSize',13);
set(gcf,'Position',[10 163 1454 464])
saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
    'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
    filesep,'figures',filesep,'FWHM_res_v2'],'eps2c')
saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
    'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
    filesep,'figures',filesep,'FWHM_res_v2'],'png')

Create plot and movie of images with displacement indicated

frames = [1 2 3 4 5 6 7];

FileName = 'movie_res.mp4';
vidObj = VideoWriter([FileName],'MPEG-4');
vidObj.Quality = 100;
vidObj.FrameRate = 1;
open(vidObj);

idx = 1;
for i = frames
    f = figure(100+i);clf;
    for m = 1:7
        subplot(3,7,m)
        imagesc(sca.x_axis*1000,sca.z_axis*1000,img{m}(:,:,i))
        ax(m) = gca;
        axis image;colormap gray;caxis([-60 0])
        title(tags{m});
        xlabel('x [mm]');
        if(m == 1)
        ylabel('y [mm]');
        end
        set(gca,'FontSize',15)

        subplot(3,7,[8:21]); hold all;
        plot(sca.x_axis*1000,img{m}(105,:,i)-max(img{m}(105,:,i)),'DisplayName',tags{m},'LineWidth',2,'DisplayName',tags{m})
        xlim([-2 2])
        ylim([-60 0])
        xlabel('x [mm]');
        ylabel('Amplitude [dB]');
    end
    subplot(3,7,[8:21]); hold all;
    plot(sca.x_axis*1000,ones(1,length(sca.x_axis))*-6,'r--','DisplayName',tags{m},'LineWidth',2,'DisplayName','-6 dB')
    linkaxes(ax);
    legend show
    set(gcf,'Position',[46 50 1083 750]);
    set(gca,'FontSize',20)

if i == 1
    mkdir([ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
        'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
        filesep,'figures'])
    saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
        'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
        filesep,'figures',filesep,'FWHM_PSF_v2'],'eps2c')
    saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
        'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
        filesep,'figures',filesep,'FWHM_PSF_v2'],'png')

else
    saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
        'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
        filesep,'figures',filesep,'FWHM_PSF_',...
        strrep(num2str(separating_distance(idx)),'.','_'),'_v2'],'eps2c')
    saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
        'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
        filesep,'figures',filesep,'FWHM_PSF_',...
        strrep(num2str(separating_distance(idx)),'.','_'),'_v2'],'png')

    idx = idx+1;
    drawnow();
    writeVideo(vidObj, getframe(f));
end
end
close(vidObj)

Warning: Directory already exists. 

Measure separability

clear separability;
frames = [2:7];
for i = frames
    %figure(101+i);clf;hold all;
    for m= 1:7
        normalized_lateral{m} =  img{m}(105,:,i)-max(img{m}(105,:,i));

        [dummy,idx_start] = min(abs(sca.x_axis*1000-(-2.5)));
        [dummy,idx_stop] = min(abs(sca.x_axis*1000-(1)));
        [dummy,idx_zero] = min(abs(sca.x_axis*1000));
        min_value = normalized_lateral{m}(idx_zero);
        [max_value,idx_max] = max(normalized_lateral{m}(idx_start:idx_stop));

        %plot(sca.x_axis(idx_start:idx_stop)*1000,normalized_lateral{m}(idx_start:idx_stop));
        %plot(sca.x_axis(idx_start+idx_max-1)*1000,max_value,'*');
        %plot(sca.x_axis(idx_zero)*1000,min_value,'*');

        separability(m,i-1) = max_value-min_value;
    end
end

Create summary plots of separability

separability_lim = 6;

f = figure;
subplot(211);hold all;
plot(separability(1,:),'-*','LineWidth',2,'DisplayName',tags{1})
plot(separability(2,:),'-*','LineWidth',2,'DisplayName',tags{2})
plot(separability(3,:),'-*','LineWidth',2,'DisplayName',tags{3})
plot(separability(4,:),'-*','LineWidth',2,'DisplayName',tags{4})
plot(separability(5,:),'-*','LineWidth',2,'DisplayName',tags{5})
plot(separability(6,:),'-*','LineWidth',2,'DisplayName',tags{6})
plot(separability(7,:),'-*','LineWidth',2,'DisplayName',tags{7})
plot([1:7],ones(7,1)*separability_lim,'LineWidth',2,'Color','r',...
    'LineStyle','--','DisplayName','6 dB limit')
legend show
xlim([1 9])
xticks([1:6])
xticklabels({num2str(separating_distance(1)) num2str(separating_distance(2))...
    num2str(separating_distance(3)) num2str(separating_distance(4)) ...
    num2str(separating_distance(5)) num2str(separating_distance(6))})
xlabel('Distance between scatterers [mm]')
ylabel('Separability [dB]');
set(gca,'FontSize',12)
saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
    'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
    filesep,'figures',filesep,'separability_1'],'eps2c')

f = figure;
subplot(212);hold all;
plot((separability(1,:)>separability_lim)-0.15,'-*','LineWidth',2,'DisplayName',tags{1})
plot((separability(2,:)>separability_lim)-0.1,'-*','LineWidth',2,'DisplayName',tags{2})
plot((separability(3,:)>separability_lim)-0.05,'-*','LineWidth',2,'DisplayName',tags{3})
plot((separability(4,:)>separability_lim),'-*','LineWidth',2,'DisplayName',tags{4})
plot((separability(5,:)>separability_lim)+0.05,'-*','LineWidth',2,'DisplayName',tags{5})
plot((separability(6,:)>separability_lim)+0.1,'-*','LineWidth',2,'DisplayName',tags{6})
plot((separability(7,:)>separability_lim)+0.15,'-*','LineWidth',2,'DisplayName',tags{7})
ylim([-0.5 1.5])
xticks([1:6])
xticklabels({num2str(separating_distance(1)) num2str(separating_distance(2)) ...
    num2str(separating_distance(3)) num2str(separating_distance(4)) num2str(separating_distance(5)) num2str(separating_distance(6))})
xlabel('Distance between scatterers [mm]')
xlim([1 9])
yticks([0 1])
yticklabels({'Not separated','Separated'})
set(gca,'FontSize',12)
legend('show')
saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
    'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
    filesep,'figures',filesep,'separability_2'],'eps2c')
saveas(f,[ustb_path,filesep,'publications',filesep,'IUS2020',filesep,...
    'Rindal_et_al_Resolution_Measured_as_Separability_Compared_to_FWHM',...
    filesep,'figures',filesep,'separability_2'],'png')

Published with MATLAB® R2020a