possible bug saving as 32-bit BMP3
Posted: 2016-07-13T14:46:06-07:00
.
Reference: viewtopic.php?f=1&t=30063
This does not work for me on IM 6.9.5.1 OSX Snow Leopard
Note: I added -blur 0x1 only to ensure that the result was not palettealpha, since without it, that is what I got.
Note: No alpha channel. The result is 24-bit, not 32-bit.
I even tried
But still no alpha channel.
From Anthony's documentation:
"If you have an older program cannot read the default BMP4 images written by
ImageMagick, (for example a Windows Background Image), you can enforce the
generation of a BMP3 format image using...
convert image BMP3:image.bmp
This format should have no transparency and should be a 'printable image',
whatever that means."
Does this mean that IM does not support transparency in BMP3 or BMP3 does not support transparency?
From http://www.fileformat.info/format/bmp/egff.htm, it would appear that BMP3 (Windows 3x and Windows NT) do not allow transparency, only BMP4. So perhaps Anthony's docs are wrong or are talking about bits per channel depths.
Another reference indicates that some tools have written special version of BMP3 to add transparency. See discussion at viewtopic.php?t=16259
Reference: viewtopic.php?f=1&t=30063
This does not work for me on IM 6.9.5.1 OSX Snow Leopard
Code: Select all
convert logo: -blur 0x1 -transparent white -type truecoloralpha BMP3:test.bmpCode: Select all
identify -verbose test.bmp
Image: test.bmp
Format: BMP3 (Microsoft Windows bitmap image (V3))
Class: DirectClass
Geometry: 640x480+0+0
Units: PixelsPerCentimeter
Type: TrueColor
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
Channel statistics:
Pixels: 307200
Red:
min: 4 (0.0156863)
max: 255 (1)
mean: 229.325 (0.899314)
standard deviation: 66.3486 (0.260191)
kurtosis: 4.26787
skewness: -2.43631
entropy: 0.234953
Green:
min: 0 (0)
max: 255 (1)
mean: 226.219 (0.887133)
standard deviation: 67.5812 (0.265024)
kurtosis: 3.00796
skewness: -2.15575
entropy: 0.272774
Blue:
min: 0 (0)
max: 255 (1)
mean: 229.065 (0.898296)
standard deviation: 60.5988 (0.237642)
kurtosis: 3.75062
skewness: -2.24566
entropy: 0.275195
Image statistics:
Overall:
min: 0 (0)
max: 255 (1)
mean: 228.203 (0.894914)
standard deviation: 64.9142 (0.254566)
kurtosis: 3.71526
skewness: -2.29045
entropy: 0.260974
I even tried
Code: Select all
convert logo: -blur 0x1 -transparent white -type truecoloralpha ppm:- | convert - BMP3:test.bmpFrom Anthony's documentation:
"If you have an older program cannot read the default BMP4 images written by
ImageMagick, (for example a Windows Background Image), you can enforce the
generation of a BMP3 format image using...
convert image BMP3:image.bmp
This format should have no transparency and should be a 'printable image',
whatever that means."
Does this mean that IM does not support transparency in BMP3 or BMP3 does not support transparency?
From http://www.fileformat.info/format/bmp/egff.htm, it would appear that BMP3 (Windows 3x and Windows NT) do not allow transparency, only BMP4. So perhaps Anthony's docs are wrong or are talking about bits per channel depths.
Another reference indicates that some tools have written special version of BMP3 to add transparency. See discussion at viewtopic.php?t=16259