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- Timestamp:
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05/12/11 03:31:58 (13 years ago)
- Author:
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mlinkert
- Comment:
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- Property Cc smithd@… added
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Property
Remaining Time
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1
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5
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Property
Summary
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Update tile-based JPEG decoder to handle images that are too large
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Support .ndpi files with width or height > 65500
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Property
Milestone
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OMERO-Beta4.3
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Unscheduled
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Property
Sprint
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2011-05-19 (12)
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v4
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v7
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| 1 | | Many .ndpi files contain JPEG streams that have a width and/or height larger than 65535 (the maximum size allowed in a JPEG stream). For images where (width * height) <= (65535 * 65535), we can solve the problem by setting an artificial width and height, then re-pack the tiles with the correct dimensions after they have been decoded. |
| | 1 | Many .ndpi files contain JPEG streams that have a width and/or height larger than 65500 (the maximum size supported by Java's JPEG decoder. The maximum size allowed in the JPEG specification is 65535, and it is not uncommon to have .ndpi files that contain much larger images. |
| 2 | 2 | |
| 3 | | For images with (width * height) > (65535 * 65535), though, we need a different strategy. |
| | 3 | After some investigation, it looks like Hamamatsu has written their very own JPEG encoder/decoder to work around the limitations in the JPEG specification, as no other decoder that I can find actually supports this. |
| | 4 | A lot of investigation has already gone into this ticket, and given the scope of work required I don't see it happening for 4.3. |
| | 5 | |
| | 6 | When we finally do have time to sort this out, the plan is roughly: |
| | 7 | |
| | 8 | 1) See if there is a way to strip off the dimension information and just read all of the tiles using Java's built-in JPEG support. We can then re-pack the tiles using the dimension information stored in the .ndpi file. |
| | 9 | |
| | 10 | 2) Failing (1), see if we can write our own Java interface to the JPEG native libraries included with the JRE that would accomplish the same thing as (1). |
| | 11 | |
| | 12 | 3) If neither (1) nor (2) work, we'll need to write our own baseline JPEG decoder that allows the image dimensions to be overridden. |
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