Package nom.tam.image

Class StreamingTileImageData

java.lang.Object

nom.tam.fits.Data

nom.tam.fits.ImageData

nom.tam.image.StreamingTileImageData

All Implemented Interfaces:

FitsElement

public class StreamingTileImageData
extends ImageData

Simple streaming image tile implementation. Useful for web applications that provide a cutout service. The idea is that the ImageData object will be extracted from an overlapping HDU (without first reading so as not to fill up the memory), and one of these objects are created for the output.

     Fits source = new Fits(myFile);
     ImageHDU imageHDU = source.getHDU(1);

     // We must manually adjust the header for the cutout image as necessary
     Header tileHeader = ...

     // Define the cutout region
     int[] tileStarts = new int[]{10, 10};
     int[] tileLengths = new int[]{45, 60};
     int[] tileSteps = new int[]{1, 1};

     // Create the cutout
     StreamingTileImageData streamingTileImageData = new StreamingTileImageData(tileHeader, imageHDU.getTiler(),
         tileStarts, tileLengths, tileSteps);

     // Write the cutout to the output
     Fits output = new Fits();
     output.addHDU(FitsFactory.hduFactory(tileHeader, streamingTileImageData));

     // The cutout happens at write time!
     output.write(outputStream);
 

Since:

1.18

Constructor Summary

Constructors

Constructor	Description
StreamingTileImageData(Header header, ImageTiler tiler, int[] corners, int[] lengths, int[] steps)	Constructor for a tile image data object.

Method Summary

Modifier and Type	Method	Description
int[]	getSteps()	Returns the striding step sizes along the various image dimensions.
void	write(ArrayDataOutput o)	Writes the contents of the element to a data sink, adding padding as necessary if the element (such as a header or data segment) is expected to complete the FITS block of 2880 bytes.

Methods inherited from class nom.tam.fits.ImageData

convertTo, from, getDimensions, getQuantizer, getTiler, getType, isComplexValued, overrideHeaderAxes, read, setBuffer, setQuantizer, toHDU

Methods inherited from class nom.tam.fits.Data

calcChecksum, detach, getData, getFileOffset, getKernel, getSize, isDeferred, isEmpty, reset, rewrite, rewriteable

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

StreamingTileImageData

public StreamingTileImageData(Header header,
 ImageTiler tiler,
 int[] corners,
 int[] lengths,
 int[] steps)
                       throws FitsException

Constructor for a tile image data object.

Parameters:

header - The header representing the desired cutout. It is the responsibility of the caller to adjust the header appropriately.

tiler - The tiler to slice pixels out with.

corners - The corners to start tiling.

lengths - The count of values to extract.

steps - The number of jumps to make to the next read. Optional, defaults to 1 for each axis.

Throws:

FitsException - If the provided Header is unreadable

Method Details

getSteps

public int[] getSteps()

Returns the striding step sizes along the various image dimensions.

Returns:

an array containing the steps sizes along the dimensions

write

public void write(ArrayDataOutput o)
           throws FitsException

Description copied from interface: FitsElement

Writes the contents of the element to a data sink, adding padding as necessary if the element (such as a header or data segment) is expected to complete the FITS block of 2880 bytes.

Specified by:

write in interface FitsElement

Overrides:

write in class ImageData

Parameters:

o - The data sink.

Throws:

FitsException - if the write was unsuccessful.