[IMAGING-94] Add ability to load partial TIFF images

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0-alpha1
• Component/s: Format: TIFF
• Assignee: Unassigned
• Reporter: Gary Lucas
• Created: 14/Oct/12 03:53
• Updated: 03/May/19 08:39
• Resolved: 12/Dec/12 05:42

Description

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));