bugGNU Octave - Bugs: bug #37368, imread errors when passing the...


bug #37368: imread errors when passing the info option

Submitted by:  Carnë Draug <carandraug>
Submitted on:  Sun 16 Sep 2012 04:58:36 PM UTC  
Category: NoneSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Matlab Compatibility
Status: FixedAssigned to: Carnë Draug <carandraug>
Originator Name: Open/Closed: Closed
Release: 3.6.2Operating System: Any

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Mon 29 Jul 2013 07:26:02 PM UTC, comment #3:

I have already fixed 2 weeks ago. It's ignoring the info option since there's nothing we can do about it.

Basically, the info structure in matlab has a list of the file offset where each page of a multipage TIFF starts. The nature of the format requires to transverse all previous pages to find where it starts. Passing such list would speed the reading of an arbitrary page. However, we can't control that using GraphicsMagick.

I have instead implemented the Frame option (matlab compatible) that should be used to read multiple pages, instead of imread in a for loop.

Carnë Draug <carandraug>
Project MemberIn charge of this item.
Fri 30 Nov 2012 07:52:50 AM UTC, comment #2:

I forgot to start the verbatim environment, only closed it. I recovered what I had submitted from the bug tracker mailing list. This is the code that was missing from the bug report

but the following fails (it should retrieve the 2nd page of a multi-page

Carnë Draug <carandraug>
Project MemberIn charge of this item.
Wed 28 Nov 2012 07:20:24 PM UTC, comment #1:

I agree that we should just ignore "Info", since Matlab just uses it for perf. Functionality it does not do anything.

Currently imread should error out if more than 3 args are passed in , like 'Index' and 'Info' at the same time. If 'Info' is passed in with the output of IMFINFO, then I do not know what is going to happen.

I'm not sure what your example is producing; I can't see it.

Mark Wistrom <mwistrom>
Sun 16 Sep 2012 04:58:36 PM UTC, original submission:


one of the options of imread (in Matlab) is "Info" which then takes the output of imfinfo to speed up the reading of the image. I understand that it's not implemented (we probably don't need it to speed up anything) but would be handy to at least ignore it. However, it only errors when there's no index used. For example, the following works fine:

Carnë Draug <carandraug>
Project MemberIn charge of this item.


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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Mon 29 Jul 2013 07:26:02 PM UTCcarandraugStatusNone=>Fixed
      Assigned toNone=>carandraug

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