Legacy ImageMagick Discussions Archive

Anthony wrote:Identify statistics seems to be currently a little confused.
Channel statistics: Alpha: seems to be showing 'opacity' values, not alpha
Histogram: is displaing alpha values
Colormap: is displaying opacity values and incorrect rgba() values.
That however may be a function of the grayscale PNG, and not the actual image colors.

Any chance that this can be made consistent and preferably show alpha. Whether it is reported as 0 to 1 or 0 to quantum range is not important, but it would be nice if it was always representing alpha.


The red colored items below say Alpha, BUT report opacity values. Can they be made consistent. The blue colored items are reporting alpha.


convert logo: -alpha on -depth 8 logo_a.png
identify -verbose logo_a.png
Image: logo_a.png
Format: PNG (Portable Network Graphics)
Class: DirectClass
Geometry: 640x480+0+0
Resolution: 72x72
Print size: 8.88889x6.66667
Units: Undefined
Type: PaletteMatte
Endianess: Undefined
Colorspace: RGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
alpha: 1-bit
Channel statistics:
Red:
min: 0 (0)
max: 255 (1)
mean: 228.364 (0.895545)
standard deviation: 70.8226 (0.277736)
kurtosis: 4.55624
skewness: -2.50539
Green:
min: 6 (0.0235294)
max: 255 (1)
mean: 229.059 (0.898272)
standard deviation: 62.94 (0.246824)
kurtosis: 3.37768
skewness: -2.23334
Blue:
min: 10 (0.0392157)
max: 255 (1)
mean: 232.288 (0.910932)
standard deviation: 55.8149 (0.218882)
kurtosis: 5.10921
skewness: -2.47931
Alpha: <--- this says alpha!
min: 0 (0) <--- these values should be 255 (1)
max: 0 (0) <--- these values should be 255 (1)
mean: 0 (0) <--- these values should be 255 (1)
standard deviation: -0 (-0)
kurtosis: 0
skewness: 0
Image statistics:
Overall:
min: 0 (0)
max: 255 (1)
mean: 172.428 (0.676187)
standard deviation: 113.736 (0.446022)
kurtosis: -1.36461
skewness: -0.740717
Histogram:
642: ( 0, 83,170,255) #0053AA rgba(0,83,170,1 <--- these values are alpha)
565: ( 1, 93,171,255) #015DAB rgba(1,93,171,1)
391: ( 1, 96,174,255) #0160AE rgba(1,96,174,1)
9: ( 1, 96,177,255) #0160B1 rgba(1,96,177,1)
10877: ( 2, 90,164,255) #025AA4 rgba(2,90,164,1)
80: ( 4, 74,166,255) #044AA6 rgba(4,74,166,1)
4: ( 6, 60,161,255) #063CA1 rgba(6,60,161,1)
14: ( 6, 79,174,255) #064FAE rgba(6,79,174,1)
167: ( 8, 6, 10,255) #08060A rgba(8,6,10,1)
1: ( 8, 64,124,255) #08407C rgba(8,64,124,1)
182: ( 10, 9, 18,255) #0A0912 rgba(10,9,18,1)
519: ( 10, 90,163,255) #0A5AA3 rgba(10,90,163,1)