possible bug creating 8-bit palettematte PNG

[fmw42]

See viewtopic.php?f=2&t=18401

The second method, still seems wrong in IM 6.6.9.1 Q16. Could someone tell me if this is a bug or am I not understanding some new feature of the PNG changes.

Thanks.

[glennrp]

There seems to be something wrong with -type palettematte outside
of the PNG encoder. The transparency also gets lost if you write a MIFF or TXT.

But using the PNG8: subformat should give what you want, without the -type
option.

[fmw42]

Thanks Glenn! Hopefully Magick will look into this.

Fred

[fmw42]

Magick,

Are you aware of this issue with -type palettematte?

Fred

[magick]

Have you tried -type palette-bilevel-matte?

[fmw42]

Why the palettebilevelmatte rather than palettematte? Please explain.

It does get mostly there:

convert logo: -transparent white -depth 8 -type palette-bilevel-matte PNG8:tmp.png
identify -verbose tmp.png
Image: tmp.png
Format: PNG (Portable Network Graphics)
Class: DirectClass <-- but should this not be pseudoclass
Geometry: 640x480+0+0
Resolution: 72x72
Print size: 8.88889x6.66667
Units: Undefined
Type: PaletteMatte
Endianess: Undefined
...
Alpha: none #00000000
Histogram:
256244: ( 0, 0, 0, 0) #00000000 none
7091: ( 4, 7, 7,255) #040707 rgba(4,7,7,1)
159: ( 6, 9, 14,255) #06090E rgba(6,9,14,1)
134: ( 6, 10, 16,255) #060A10 rgba(6,10,16,1)
70: ( 9, 13, 19,255) #090D13 rgba(9,13,19,1)