Legacy ImageMagick Discussions Archive

IM 6.6.6.10 Q16 (hdri) Mac OSX Tiger

creating a gradient with or without -alpha off, reports an opaque alpha channel and type grayscalematte


convert -size 256x256 gradient: grad256.png
identify -verbose grad256.png

Image: grad256.png
Format: PNG (Portable Network Graphics)
Class: DirectClass
Geometry: 256x256+0+0
Resolution: 72x72
Print size: 3.55556x3.55556
Units: Undefined
Type: GrayscaleMatte
Base type: GrayscaleMatte
Endianess: Undefined
Colorspace: RGB
Depth: 8-bit
Channel depth:
gray: 8-bit
alpha: 1-bit
Channel statistics:
Gray:
min: 0 (0)
max: 255 (1)
mean: 127.5 (0.5)
standard deviation: 73.9003 (0.289805)
kurtosis: -1.20004
skewness: 1.26355e-12
Alpha:
min: 255 (1)
max: 255 (1)
mean: 255 (1)
standard deviation: -0 (-0)
kurtosis: 0
skewness: 0
Histogram:
256: ( 0, 0, 0,255) #000000 black
256: ( 1, 1, 1,255) #010101 rgba(1,1,1,1)
256: ( 2, 2, 2,255) #020202 rgba(2,2,2,1)
256: ( 3, 3, 3,255) #030303 grey1
256: ( 4, 4, 4,255) #040404 rgba(4,4,4,1)
256: ( 5, 5, 5,255) #050505 grey2




convert -size 256x256 gradient: -alpha off grad256_aoff.png
identify -verbose grad256_aoff.png

Image: grad256_aoff.png
Format: PNG (Portable Network Graphics)
Class: DirectClass
Geometry: 256x256+0+0
Resolution: 72x72
Print size: 3.55556x3.55556
Units: Undefined
Type: GrayscaleMatte
Base type: GrayscaleMatte
Endianess: Undefined
Colorspace: RGB
Depth: 8-bit
Channel depth:
gray: 8-bit
alpha: 1-bit
Channel statistics:
Gray:
min: 0 (0)
max: 255 (1)
mean: 127.5 (0.5)
standard deviation: 73.9003 (0.289805)
kurtosis: -1.20004
skewness: 1.26355e-12
Alpha:
min: 255 (1)
max: 255 (1)
mean: 255 (1)
standard deviation: -0 (-0)
kurtosis: 0
skewness: 0
Histogram:
256: ( 0, 0, 0,255) #000000 black
256: ( 1, 1, 1,255) #010101 rgba(1,1,1,1)
256: ( 2, 2, 2,255) #020202 rgba(2,2,2,1)
256: ( 3, 3, 3,255) #030303 grey1
256: ( 4, 4, 4,255) #040404 rgba(4,4,4,1)
256: ( 5, 5, 5,255) #050505 grey2

The problem you reported is fixed in ImageMagick 6.6.7-0 Beta, thanks to Glenn.

Thanks Glenn,

The following is working properly in IM 6.6.7.0 Q16 (hdri) Mac OSX Tiger

convert -size 256x256 gradient: -alpha off grad256_aoff.png
identify -verbose grad256_aoff.png

Fred