http://www.k-wave.org/forum/topic/hounsfield2density-not-working-for-ct-file Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 01:50:10 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/hounsfield2density-not-working-for-ct-file#post-8285 Sat, 07 Aug 2021 08:03:32 +0000 Bradley Treeby 8285@http://www.k-wave.org/forum/ <p>You can often figure out what to do by looking at the error messages. This time it says</p> <p><code>Inputs must be floats, namely single or double</code> </p> <p>This means it doesn't like that your image values are integers. You could try something like:</p> <p><code>density = hounsfield2density(single(nifti_file));</code> </p> http://www.k-wave.org/forum/topic/hounsfield2density-not-working-for-ct-file#post-8282 Fri, 06 Aug 2021 16:31:45 +0000 Pmartc36 8282@http://www.k-wave.org/forum/ <p>An error still pops up:</p> <p>WARNING: makeGrid will be deprecated in a future version of k-Wave.<br /> Update codes to use the syntax kgrid = kWaveGrid(...).</p> <p>Error using polyval (line 67)<br /> Inputs must be floats, namely single or double.</p> <p>Error in hounsfield2density (line 63)<br /> density(ct_data &lt; 930) = polyval([1.025793065681423, -5.680404011488714], ct_data(ct_data &lt; 930));</p> <p>Error in nifti_test01 (line 20)<br /> density = hounsfield2density(nifti_file);</p> <p>&gt;&gt; </p> http://www.k-wave.org/forum/topic/hounsfield2density-not-working-for-ct-file#post-8280 Fri, 06 Aug 2021 09:40:35 +0000 Bradley Treeby 8280@http://www.k-wave.org/forum/ <p>The error message suggests you put the variable name in quotes:</p> <pre><code>Error in nifti_test01 (line 3) [density, sound_speed] = hounsfield2density(&#39;nifti_file&#39;);</code></pre> <p>What happens if you remove them? </p> http://www.k-wave.org/forum/topic/hounsfield2density-not-working-for-ct-file#post-8278 Fri, 06 Aug 2021 04:44:32 +0000 Pmartc36 8278@http://www.k-wave.org/forum/ <p>Hello there, </p> <p>I've ran function hounsfield2density on a nifti file but this error keeps coming up. Here is the error log.</p> <p>&gt;&gt; whos nifti_file<br /> Name Size Bytes Class Attributes</p> <p> nifti_file 260x311x260 42047200 int16 </p> <p>&gt;&gt; nifti_test01<br /> Error using zeros<br /> Input following 'like' is not a numeric or logical array.</p> <p>Error in hounsfield2density (line 59)<br /> density = zeros(size(ct_data), 'like', ct_data);</p> <p>Error in nifti_test01 (line 3)<br /> [density, sound_speed] = hounsfield2density('nifti_file');</p> <p>This is the code I used.</p> <p>nifti_file = niftiread('att_map.nii');<br /> niftiinfo('t1w_pct.nii');</p> <p>%% Create the computational grid</p> <p>Nx = 400;<br /> Ny = 400;<br /> Nz = 400;<br /> dx = 50e-6;<br /> dy = 50e-6;<br /> dz = 50e-6;</p> <p>kgrid = makeGrid(Nx, dx, Ny, dy, Nz, dz);</p> <p>%% Define medium properties (using hounsfield2density</p> <p>density = hounsfield2density(nifti_file);</p> <p>Any suggestion as to what I should do? </p>