Ticket #1421 (closed defect: fixed)
Opened 2012-08-17T15:08:53-05:00
Last modified 2012-08-20T13:58:08-05:00
Signed 8-bit test images don't survive IJ2->IJ1->IJ2 roundtrip
| Reported by: | aivar | Owned by: | bdezonia |
|---|---|---|---|
| Priority: | minor | Milestone: |
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| Component: | Core | Version: | |
| Severity: | serious | Keywords: | |
| Cc: | Blocked By: | ||
| Blocking: | #1420 |
Description
Create a test ramp image (File\New\Image) with signed 8-bit, the image looks fine with a grayscale ramp, but if you apply a LUT (Image/Lookup Tables/Fire) the LUT range is distorted.
(This is the first screen capture in luts.png, attached to parent ticket 1420.)
The initial range of values for the ramp image is -128 to 127, from top left to lower right corner. After you apply a LUT the range becomes 0 to 127. With the probe tool you can see values in the white area on the left are all 127. Values at the diagonal black line are 0, going to 127 in the lower right corner.