Summary
- I am reading a large binary file which contains image data.
- Cumulative Count Cut analysis is performed on data [It requires another array with same size as the image].
- The data is stretched between 0 to 255 stored in
BufferedImagepixel by pixel, to draw the image on JPanel. - On this image, zooming is performed using
AffineTransform.
Problems
Small Image(<.5GB)
1.1 When I am increasing the scale factor for performing zooming, after a
point exception is thrown:-
java.lang.OutOfMemoryError: Java heap space.
Below is the code used for zooming-
scaled = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
Graphics2D g2d = (Graphics2D)scaled.createGraphics();
AffineTransform transformer = new AffineTransform();
transformer.scale(scaleFactor, scaleFactor);
g2d.setTransform(transformer);
- Large Image(>1.5GB)
- While loading a huge image(>1.5GB), same exception occurs as appeared in 1.1, even is the image is small enough to be loaded, sometimes, I get the same error.
Solutions Tried
- I tried using BigBufferedImage in place of BufferedImage to store the stretched data.
BigBufferedImage image = BigBufferedImage.create(newCol,newRow, BufferedImage.TYPE_INT_ARGB); But it couldn't be passed to
g2d.drawImage(image, 0, 0, this);because the repaint method of JPanel just stops for some reason.I tried loading image in low resolution where pixel is read and few columns and rows are jumped/skipped. But the problem is how to decide what number of pixels to skip as image size varies therefore I am unable to decide how to decide the jump parameter.
MappedByteBuffer buffer = inChannel.map(FileChannel.MapMode.READ_ONLY,0, inChannel.size());
buffer.order(ByteOrder.LITTLE_ENDIAN);
FloatBuffer floatBuffer = buffer.asFloatBuffer();
for(int i=0,k=0;i<nrow;i=i+jump) /*jump is the value to be skipped, nrow is height of image*/
{
for(int j=0,l=0;j<ncol1;j=j+jump) //ncol is width of image
{
index=(i*ncol)+j;
oneDimArray[(k*ncolLessRes)+l] = floatBuffer.get(index);//oneDimArray is initialised to size of Low Resolution image.
l++;
}
k++;
}
The problem is to decide how many column and row to skip i.e what value of jump should be set.
- I tried setting Xmx but image size varies and we cannot dynamically set the Xmx values. Here are some values -
table, th, td {
border: 1px solid black;
}<table style="width:100%">
<tr>
<th>Image Size</th>
<th>Xmx</th>
<th>Xms</th>
<th>Problem</th>
</tr>
<tr>
<td>83Mb</td>
<td>512m</td>
<td>256m</td>
<td>working</td>
</tr>
<tr>
<td>83Mb</td>
<td>3096m</td>
<td>2048m</td>
<td>System hanged</td>
</tr>
<tr>
<td>3.84Gb</td>
<td>512m</td>
<td>256m</td>
<td>java.lang.OutOfMemoryError: Java heap space
</tr>
<tr>
<td>3.84Gb</td>
<td>3096m</td>
<td>512m</td>
<td>java.lang.OutOfMemoryError: Java heap space
</tr>
</table>- For this I tried finding memory allocated to program:-
try(BufferedWriter bw= new BufferedWriter(new FileWriter(dtaFile,true))){
Runtime runtime=Runtime.getRuntime();
runtime.gc();
double oneMB=Math.pow(2,20);
long[] arr= Instream.range(0,(int)(10.432*long.BYTES*Math.pow(2,20))).asLongStream().toArray();
runtime.gc();
long freeMemory= runtime.freeMemory();
long totalMemory= runtime.totalMemory();
long usedMemory= totalMemory-freeMemory;
long maxMemory= runtime.maxMemory();
String fileLine= String.format(" %9.3f %9.3f %9.3f " , usedMemory/oneMb, freeMemory/oneMB, totalMemory/oneMb, maxMemory/oneMB);
bw.write();
}
Following results were obtained
Memory Allocation
This approach failed because the available memory increases as per usage of my code. As a result it will not be useful for me to make a decision for jump.
Result Expected
A way to access the amount of available memory before the loading of the image so that I could use it to make decision on value of the jump. Is there any other alternative to decide jump value (i.e., how much I can lower the resolution?).
