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[Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel
From: |
anonymous |
Subject: |
[Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format |
Date: |
Sun, 03 Apr 2011 14:02:21 +0000 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0 |
URL:
<http://savannah.gnu.org/bugs/?32986>
Summary: imread() reads .png with alpha channel as an
unexpected array format
Project: GNU Octave
Submitted by: None
Submitted on: Sun 03 Apr 2011 02:02:20 PM UTC
Category: None
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name: Jeremy
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 3.2.4
Operating System: GNU/Linux
_______________________________________________________
Details:
[img, map, alpha] = imread('transparency_pic.png');
"map" and "alpha" will be empty variables. "img" will be an MxNx2 array (if
grayscale+alpha) or an MxNx4 array (if color+alpha) -- The manual entry for
imread says that "img" should be either MxN (black and white, grayscale) or
MxNx3 (color).
I'm guessing that the data for the alpha channel should be stored in the
"alpha" variable, not as an extra dimension in "img".
img = imread('transparency_pic.png');
imwrite(img, 'copy.png');
...succeeds if _transparency_pic.png_ is color+alpha, but fails if
_transparency_pic.png_ is grayscale+alpha:
error: imwrite: invalid dimensions for truecolor image
error: called from:
error: /usr/share/octave/3.2.4/m/image/imwrite.m at line 113, column 9
Tested on both Ubuntu 10.10 (repository version, 3.2.4) and Windows 7 (Octave
Forge version, 3.2.4)
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?32986>
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- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format,
anonymous <=
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, Rik, 2011/04/04
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, anonymous, 2011/04/05
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, anonymous, 2011/04/05
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, anonymous, 2011/04/05
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, Rik, 2011/04/05
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, anonymous, 2011/04/09
- [Octave-bug-tracker] [bug #32986] imread() reads .png with alpha channel as an unexpected array format, anonymous, 2011/04/13