org.hd.d.pg2k.ai.scorer
Class AbstractImgScorer

java.lang.Object
  org.hd.d.pg2k.ai.scorer.AbstractScorer
      org.hd.d.pg2k.ai.scorer.AbstractImgScorer

All Implemented Interfaces:

ScorerIF

Direct Known Subclasses:

LocalSampler, SimpleExposure

public abstract class AbstractImgScorer
extends AbstractScorer
implements ScorerIF

Base interface to compute the score and confidence for a 2D still image. All methods in this interface are guaranteed to be "safe" insofaras they will complete in "reasonable" time with reasonable heap memory (and other resource, eg stack) and without doing anything that wouldn't be allowed in a minimal Applet/JWS sandbox.

All classes implementing this interface should be completely thread-safe in their implementation of the computeScoreAndConfidence() method, and preferrably purely functional (no visible side-effects), with as many concurrent threads as required safely doing separate computations in any one instance.

Classes implementing this interface should, where possible, do their calculations using integer arithmetic, since FPUs to support float/double calaculations may be a scarce resource on newer highly-threaded CPUs such as Sun's Niagara.

TODO: At least tie the cache to the AEP/pipeline, not static.

_tnBICache

private static final java.util.Map<java.lang.String,java.lang.ref.SoftReference<java.awt.image.BufferedImage>> _tnBICache

Private static cache from exhibit name to expanded (std) thumbnail image. This exists to avoid having to unpack thumbnail images repeatedly.

The expanded images are held via SoftReferences to allow them to be ditched in case of memory shortage, and when individual thumbnails stop being used.

The cache key is the (full) exhibit name on the basis that thumbnails hardly ever change once created. This also means that we will stop hitting any thumbnail caches in the data pipeline once we have fetched a thumbnail once.

This cache is thread-safe and highly concurrent.

TODO: Deal with the case when a thumbnail IS changed/improved.

AbstractImgScorer

public AbstractImgScorer()

Create simple non-parameterised instance.

AbstractImgScorer

public AbstractImgScorer(java.lang.String nameAndParameters)

Create parameterised version.

AbstractImgScorer

public AbstractImgScorer(java.lang.String baseName,
                         java.util.List<ScorerParam> parameters)

Create parameterised version.

computeScoreAndConfidence

public abstract ScoreAndConf computeScoreAndConfidence(java.awt.image.RenderedImage stillImage)

Compute score [-1,+1] and confidence[0,+1] for given image; never null. This routine must NOT alter the image.

Parameters:

stillImage - non-null still 2D image; if greater than 256x256 pixels then will be internally scaled

computeScoreAndConfidence

public ScoreAndConf computeScoreAndConfidence(SimpleExhibitPipelineIF dataSource,
                                              java.lang.String exhibitName)
                                       throws java.io.IOException

Implement core/generic compute method specially for image types. For any suitable 2D still image type that has a standard thumbnail, this uses calls the computeScoreAndConfidence(RenderedImage) method with that thumbnail.

We use the standard thumbnail as being representative of the full image (and usually good enough for a human to make a judgement from) with out requiring all the system resources of the full image.

For non-image types (or images with no thumbnails possible) this returns (0,0) to indicate that it does not have a view.

Specified by:

computeScoreAndConfidence in interface ScorerIF

Parameters:

dataSource - souce of exhibit data and metadata; never null

exhibitName - name of exhibit; must be syntactically valid and not null

Throws:

java.io.IOException - in case of I/O difficulties, or when a thumbnail is not currently available but may be later (upon retry)