bugGNU Octave - Bugs: bug #45662, Do not complain about being...


bug #45662: Do not complain about being limited to 16 bits per pixel

Submitter:  Orion Poplawski <opoplawski>
Submitted:  Thu 30 Jul 2015 10:27:21 PM UTC
Category:  Libraries Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Other
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * 4.0.0 Operating System:  * GNU/Linux
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Mon 25 Jan 2016 11:00:22 AM UTC, comment #2: 

Carnë, can we close this after you changed the warning depth to 16 from 32 last November?

Lachlan Andrew <lachlan>
Fri 31 Jul 2015 10:53:26 AM UTC, comment #1: 

The other side of the story, is that with quantum-depth 16, images of 32 bitdepth will always be read as 16 bit. Worse, GraphicsMagick won't tell us if the file was of a different bitdepth. This means that we never know that we  failed to read the file correctly.  Would be great if we could print the warning only if the file being read was of higher bitdepth but GM does not allow this.

So, to be on the safe side, we always give the warning.  But since Octave 4.0 this warning has the ID "Octave:GraphicsMagic-Quantum-Depth" so at least users can disable it.

Maybe someone has different opinion about giving warnings.

Carnë Draug <carandraug>
Project Member
Thu 30 Jul 2015 10:27:21 PM UTC, original submission:  

>> I = imread("img006.jpg")

warning: your version of GraphicsMagick limits images to 16 bits per pixel
warning: called from
    imformats>default_formats at line 256 column 11
    imformats at line 79 column 3
    imageIO at line 106 column 11
    imread at line 106 column 30

yet http://wiki.octave.org/GraphicsMagick#Quantum_depth states:

Warning: Increasing quantum depth may have a dramatic increase in memory usage. If you use QuantumDepth 32, all images will be read with that precision even if they were saved with 8bit. This means that a 100MB 8bit image will temporarily take 400MB memory, or more if the image was compressed and they usually are, before Octave resizes it back down to 100MB. Because of this, because 32 bit integers images are rare, and because GraphicsMagick does not handle floating point, it's recommended to use QuantumDepth of 16.

If it is recommended, do not warn about it.

Orion Poplawski <opoplawski>


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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-01-25 carandraug StatusNone Fixed
        Open/ClosedOpen Closed

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