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[Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge
From: |
Mike Miller |
Subject: |
[Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image |
Date: |
Fri, 24 Jul 2015 05:19:00 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Iceweasel/38.1.0 |
Follow-up Comment #15, bug #45565 (project octave):
When I open the attached images, I see the following from GraphicsMagick:
$ gm identify *bmp
D2801fullsize_Created by Octave.bmp BMP 480x480+0+0 DirectClass 8-bit 675.1Ki
0.000u 0:01
D2801fullsize_Saved by ImageJ.bmp[1] BMP 480x480+0+0 PseudoClass 256c 8-bit
226.1Ki 0.000u 0:01
foo-octave.bmp[2] BMP 256x100+0+0 PseudoClass 256c 8-bit 51.2Ki 0.000u 0:01
So GraphicsMagick sees D2801fullsize_Saved by ImageJ.bmp and foo-octave.bmp
both as 8-bit 256-color indexed images.
But checking out these files with Python PIL gives differences:
D2801fullsize_Created by Octave.bmp: BMP 480x480 RGB {'dpi': (75, 75),
'compression': 0} [('raw', (0, 0, 480, 480), 54, ('BGR', 1440, -1))]
D2801fullsize_Saved by ImageJ.bmp: BMP 480x480 L {'dpi': (0, 0),
'compression': 0} [('raw', (0, 0, 480, 480), 1078, ('L', 480, -1))]
foo-octave.bmp failed: Unsupported BMP compression (1)
If I create a new BMP file with Octave the same size as the working
D2801fullsize_Saved by ImageJ.bmp (480x480) with
octave:1> x = uint8 (randi ([0, 255], 480, 480));
octave:2> imwrite (x, gray (256), "foo.bmp");
octave:3> whos
Variables in the current scope:
Attr Name Size Bytes Class
==== ==== ==== ===== =====
x 480x480 230400 uint8
octave:4> system ("ls -l foo.bmp");
-rw-r----- 1 mike mike 461076 Jul 24 01:06 foo.bmp
Don't know why but the saved file is twice the size of the matrix in memory.
The gm utility still claims that it contains 8-bit pixels.
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- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, (continued)
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Carnë Draug, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Ian Journeaux, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Mike Miller, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Ian Journeaux, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Ian Journeaux, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Carnë Draug, 2015/07/17
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Carnë Draug, 2015/07/20
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Ian Journeaux, 2015/07/20
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Mike Miller, 2015/07/20
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Ian Journeaux, 2015/07/20
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image,
Mike Miller <=
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image, Mike Miller, 2015/07/24
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit image to BMP creates a 24-bit image, Mike Miller, 2015/07/24
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit image to BMP creates a 24-bit image, Ian Journeaux, 2015/07/25
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit image to BMP creates a 24-bit image, Carnë Draug, 2015/07/28
- [Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit image to BMP creates a 24-bit image, Carnë Draug, 2015/07/28