Reading data from an UFF file recorded with the Verasonics CPWC_L7 example

In this example we show how to read channel and beamformed data from a UFF (Ultrasound File Format) file recorded with the Verasonics example. You will need an internet connectionto download data. Otherwise, you can run the CPWC_L7.m Verasonics example so the file 'L7_CPWC_193328.uff' is in the current path.

by Alfonso Rodriguez-Molares alfonso.r.molares@ntnu.no and Ole Marius Hoel Rindal olemarius@olemarius.net 15.05.2017

Contents

Checking the file is in the path

To read data from a UFF file the first we need is, you guessed it, a UFF file. We check if it is on the current path and download it from the USTB websever.

% data location
url='http://ustb.no/datasets/';      % if not found data will be downloaded from here
local_path = [ustb_path(),'/data/']; % location of example data in this computer
addpath(local_path);
filename='L7_CPWC_193328.uff';

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

Reading channel data

Now that the file is on the path let us create a UFF object to interact with the file. We open it in "append" mode.

uff_file=uff(filename)

uff_file = 

  uff with properties:

    filename: 'L7_CPWC_193328.uff'
     version: 'v1.0.1'
        mode: 'append'
     verbose: 1

Let's first check if we are lucky and the file allready contains beamformed_data that we can display.

display=true;
content = uff_file.index('/',display);

has_b_data = false;
for i = 1:length(content)
    if strcmp(content{i}.class,'uff.beamformed_data')
        has_b_data = true; % We found a beamformed data object!
    end
end

UFF: Contents of L7_CPWC_193328.uff at /
   - /b_data: b_data [uff.beamformed_data] size(1,1)
   - /channel_data: channel_data [uff.channel_data] size(1,1)

If it doesn't have any beamformed data at least it should have some channel_data. So let's read that. If the file did have beamformed data, will will jump straight to the display part later on :)

if ~has_b_data

    channel_data=uff_file.read('/channel_data');

And then the normal routine of defining the scan,

    sca=uff.linear_scan();
    sca.x_axis = linspace(channel_data.probe.x(1),channel_data.probe.x(end),256).';
    sca.z_axis = linspace(0,50e-3,256).';

setting up and running the beamforming

    bmf=beamformer();
    bmf.channel_data=channel_data;
    bmf.scan=sca;

    bmf.receive_apodization.window=uff.window.none;
    bmf.receive_apodization.f_number=1.7;
    bmf.receive_apodization.apex.distance=Inf;

    bmf.transmit_apodization.window=uff.window.none;
    bmf.transmit_apodization.f_number=1.7;
    bmf.transmit_apodization.apex.distance=Inf;

    b_data=bmf.go({process.delay_matlab process.coherent_compounding});

Now we can save this beamformed image to that file, so that we don't have to wait for the beamforming again.

    uff_file.write(b_data,'b_data');

end

And finally display the image.

b_data.plot();

Published with MATLAB® R2015a