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From "Gary Lucas (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IMAGING-94) Add ability to load partial TIFF images
Date Sun, 14 Oct 2012 03:54:02 GMT
Gary Lucas created IMAGING-94:
---------------------------------

             Summary: Add ability to load partial TIFF images
                 Key: IMAGING-94
                 URL: https://issues.apache.org/jira/browse/IMAGING-94
             Project: Commons Imaging
          Issue Type: New Feature
          Components: Format: TIFF
            Reporter: Gary Lucas


For most Apache Commons Imaging applications, the easiest way to obtain a sub image from a
file is to simply use the Imaging class to load it as a BufferedImage and then use BufferedImage’s
getSubimage() method to extract the portion of the image you wish to use.  The TIFF format
presents a special problem because it is very common to have huge images (100’s or even
1000’s of megapixel).  Examples include Landsat satellite images, global-scale GeoTIFF images,
etc.  In such cases, loading the entire image into memory is not practical because it would
require too much memory.  For example, I am currently working with a 21600 by 10800 image
that requires more than 890 megabytes to store as a BufferedImage.  That value is pushing
the limit of what I can configure Java to handle on my particular OS.

I propose to implement features for TIFF files that would permit Commons Imaging to load a
partial image of a TIFF file using only the amount memory actually needed to hold the sub-image.

These changes would not interfere with normal operations of TIFF files and would not affect
other image formats.  If there were a need for similar features for other image formats, they
could be phased in through future changes.

The specification for a sub-image would be through the use of the params argument in the getBufferedImage
call as follows:

        HashMap<String, Object> params = new HashMap<String, Object>();

        params.put(TiffConstants.PARAM_KEY_SUBIMAGE_X, new Integer(x));
        params.put(TiffConstants.PARAM_KEY_SUBIMAGE_Y, new Integer(y));
        params.put(TiffConstants.PARAM_KEY_SUBIMAGE_WIDTH, new Integer(width));
        params.put(TiffConstants.PARAM_KEY_SUBIMAGE_HEIGHT, new Integer(height));


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