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https://issues.apache.org/jira/browse/IMAGING-251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17075816#comment-17075816
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Gary Lucas commented on IMAGING-251:
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I have submitted a Pull Request with initial changes to support access to TIFF
images with floating-point data formats. The work I submitted enables Commons
Imaging to read BufferedImages from some floating-point sources, though I am
still looking for example files of other variations so that I can broaden the
capabilities of the code. I am also working on the numerical data-access
functionality that was the reason for this original issue.
One of the features of the new code is that it allows an application to
specify a palette for mapping floating-point values to colors. This is a new
feature for the Commons Imaging TIFF support. The palette is specified by
providing the API with a custom "Photometric Interpreter". Ordinarily, Commons
Imaging uses its built-in interpreters to map image data to colors. This change
permits an application to supply interpreters based on information (user
preferences) that is outside the scope of the TIFF file. I have included a
simple example application called ReadAndRenderFloatingPoint.java which is
located in the test space in the standard Commons Imaging code base.
I've attached a picture showing the results from a US Geological Survey
elevation data product. This example was built using a list of palette
specifications. One specification maps all negative (ocean) elevations to
blue. The other specification maps positive (land) elevations to shades of
gray. I came up with the design for this API by looking at the on-line help
for a number of applications including ArcGIS, R, Matlab, and GRASS.
!Imaging252_USGS_n38w077.jpg!
> Support TIFF standard floating point data
> -----------------------------------------
>
> Key: IMAGING-251
> URL: https://issues.apache.org/jira/browse/IMAGING-251
> Project: Commons Imaging
> Issue Type: New Feature
> Components: Format: TIFF
> Affects Versions: 1.x
> Reporter: Gary Lucas
> Priority: Major
> Fix For: 1.x
>
> Attachments: Imaging252_USGS_n38w077.jpg
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Commons Imaging does not support the floating-point format included in the
> TIFF specification. There are prominent data sources that issue products in
> this format. The ability to support this information would open up new
> application areas for Commons Imaging.
> TIFF is often used as a mechanism for distributing data from geophysical
> applications in the form of GeoTIFF files. Some of this is not imagery, but
> data. For example, the US Geological Survey is currently releasing
> high-resolution elevation data grids for the 3DEP program under the name
> Cloud-Optimized GeoTIFF (COG). It is a substantial data set with significant
> potential commercial and academic applications.
> To access this data means modifying the TIFF DataReaderStrips and
> DataReaderTile classes to recognize floating point data (which is typically
> indicated using TIFF tag #339, SampleFormat). Also, returning the data in the
> form of a BufferedImage makes no sense at all, so the API on the
> TiffImageParser and supporting classes would need additional methods to
> return arrays of floats. The good news here is that that requirement would
> mean adding new methods to the classes rather than making significant changes
> to existing classes. So the probability of unintended consequences or new
> bugs in existing code would be minimized.
> Specification details for floating-point are given in the main TIFF-6
> documentations and Adobe Photoshop TIFF Technical Note 3.
>
> I am willing to volunteer to make these changes provided that there is
> interest and a high probability that my contributions would be evaluated and,
> if suitable, integrated into the Commons Imaging code base.
> Thank you for your attention in this matter.
>
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