After playing around a little bit, I have come up with the following that's not currently working. Could you please advise me why this isn't working.<div><br></div><div>Thanks</div><div><br></div><div>put() {</div>
<div> // Organ data contains a list of char[]</div><div><div> final char[] storedCharArray = organData.get(imageNumber);</div><div> final char[] binaryCharArray = getCharArray(binaryOrgan);</div><div>
<br></div><div> int i=0;</div><div> for (char binaryData : binaryCharArray) {</div><div> char storedData = storedCharArray[i];</div><div> if (binaryData == 0)</div><div> storedData &= ~(1 << bitNumber);</div>
<div> else</div><div> storedData |= (1 << bitNumber);</div><div> storedCharArray[i] = storedData;</div><div> ++i;</div><div> }</div><div><br></div><div>get() {</div>
<div><div> vtkImageData binaryImage = // Get blank image of correct dimensions, orientation, spacing, etc.</div><div> final char[] storedCharArray = organData.get(imageNumber);</div><div> final char[] binaryCharArray = getCharArray(binaryImage);</div>
<div><br></div><div> int i=0;</div><div> for (char storedData : storedCharArray) {</div><div> binaryCharArray[i] = (char)((storedData >> bitNumber) & 1);</div><div> ++i;</div>
<div> }</div><div> setCharArray(binaryImage, binaryCharArray);</div></div><div><br></div><div><div>private void setCharArray(vtkImageData image, char[] array) {</div><div> ((vtkCharArray)image.GetPointData().GetScalars()).SetJavaArray(array);</div>
<div> }</div><div><br></div><div> private char[] getCharArray(vtkImageData image) {</div><div> vtkPointData points = image.GetPointData();</div><div> vtkCharArray ca = (vtkCharArray)points.GetScalars();</div>
<div> char[] chars = ca.GetJavaArray();</div><div> return chars;</div><div> }</div></div><div><br></div><br><div class="gmail_quote">On Fri, Mar 25, 2011 at 12:48 PM, David Gobbi <span dir="ltr"><<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">In python it is possible to access the VTK data arrays directly via<br>
python's buffer interface, so that's what I use when I want to quickly<br>
move pixel data back and forth from python to VTK. It allows me to<br>
use a VTK array (including the one that the image uses to store its<br>
pixels) as if it was a native python array.<br>
<br>
I have a feeling that the only way you will be able to rapidly do VTK<br>
pixel operations of any kind from Java, is if someone adds a similar<br>
feature to the Java wrappers.<br>
<font color="#888888"><br>
- David<br>
</font><div><div></div><div class="h5"><br>
<br>
On Fri, Mar 25, 2011 at 1:31 PM, Jonathan Morra <<a href="mailto:jonmorra@gmail.com">jonmorra@gmail.com</a>> wrote:<br>
> Your understanding is correct, however I cannot<br>
> use GetScalarComponentAsDouble and SetScalarComponentAsDouble because they<br>
> are way too slow in Java. Do you have any other suggestions for how to do<br>
> this or will I have to write it myself in C++?<br>
><br>
> On Fri, Mar 25, 2011 at 12:29 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>> wrote:<br>
>><br>
>> Hi Jonathan,<br>
>><br>
>> If I understand correctly, you have several binary images with exactly<br>
>> the same dimensions. And you want to collapse them into a single<br>
>> image, by storing a bitfield in the pixels of that image. So:<br>
>><br>
>> To set bit "i" in pixel "xyz" (C++ code):<br>
>> int a = int(image.GetScalarComponentAsDouble(x, y, z, 0));<br>
>> a |= (1 << i);<br>
>> image.SetScalarComponentAsDouble(x, y, z, a);<br>
>><br>
>> To clear bit "i" in pixel "xyz":<br>
>> int a = int(image.GetScalarComponentAsDouble(x, y, z, 0));<br>
>> a &= ~(1 << i);<br>
>> image.SetScalarComponentAsDouble(x, y, z, a);<br>
>><br>
>> To test bit "i" in pixel "xyz":<br>
>> int a = int(image.GetScalarComponentAsDouble(x, y, z, 0));<br>
>> return ((a >> i) & 1);<br>
>><br>
>> But I'm not sure if this is what you are trying to do. I didn't fully<br>
>> understand your pseudocode.<br>
>><br>
>> - David<br>
>><br>
>><br>
>><br>
>> On Fri, Mar 25, 2011 at 1:08 PM, Jonathan Morra <<a href="mailto:jonmorra@gmail.com">jonmorra@gmail.com</a>><br>
>> wrote:<br>
>> > I'm in Java and storing a large number of binary vtkImageData's. I know<br>
>> > this is inefficient, and am searching for a better way to store them.<br>
>> > Right<br>
>> > now I have a hash of the vtkImageData's and a get/put function.<br>
>> > Basically I<br>
>> > want to mimic this get/put but with better storage. I was thinking one<br>
>> > way<br>
>> > to do this is to use bitwise logical operations to store the information<br>
>> > in<br>
>> > the binary masks. For instance, if we have 2 binary images, then we<br>
>> > could<br>
>> > store that information in 1 vtkImageData using the following pseudo<br>
>> > code.<br>
>> > private static final int IMAGE1_BIT_CHANNEL = 0;<br>
>> > private static final int IMAGE2_BIT_CHANNEL = 1;<br>
>> > private vtkImageData storedImage;<br>
>> > vtkImageData get(String image) {<br>
>> > int channel = image eq "image1" ? IMAGE1_BIT_CHANNEL :<br>
>> > IMAGE2_BIT_CHANNEL;<br>
>> > vtkImageData return = new vtkImageData();<br>
>> > foreach (pixel in storedImage)<br>
>> > if (pixel at bit channel)<br>
>> > return[pixel] = 1;<br>
>> > else<br>
>> > return[pixel] = 0;<br>
>> > return return;<br>
>> > }<br>
>> > void put(String image, vtkImageData binaryImage) {<br>
>> > int channel = image eq "image1" ? IMAGE1_BIT_CHANNEL :<br>
>> > IMAGE2_BIT_CHANNEL;<br>
>> > foreach (pixel in binaryImage)<br>
>> > if (pixel)<br>
>> > storedImage at bit in channel = 1;<br>
>> > else<br>
>> > storedImage at bit in channel = 0;<br>
>> > }<br>
>> > This could be extended easily for 8 channels for a char image for<br>
>> > instance.<br>
>> > This operation would have to be very fast though cause it is done often<br>
>> > on<br>
>> > the UI thread.<br>
>> > 1. Is there a way to do this in VTK with Java?<br>
>> > 2. Is this the best scheme for accomplishing my goal?<br>
>> > 3. Is there a better scheme for doing this?<br>
>> > Thanks.<br>
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>> ><br>
><br>
><br>
</div></div></blockquote></div><br></div>