XnView Software

XnViewMP 1.4.2
Windows11 (22H2), display resolution 3840x2160, dpi scale 150%

Viewer - Edit palette dialog

Issue
It is not possible to set transparency to multiple indexes at once.
No matter how many indexes you go through with ticking checkbox, transparency will be applied only to the last one.
It shall be possible to set transparency to as many indexes as required, and they applied all to image when OK button is pressed.

8bits palette support only 1 index

xnview wrote: Fri Feb 03, 2023 1:45 pm 8bits palette support only 1 index

What about test_png_B.png, is it still valid 8bit png?
TweakPNG allows to edit alpha channel of individual color.

Also note the handy indicator of transparency in TweakPNG (red oval on x scale under each color)

Related

• suggestions
  Edit palette - indexes selection, color and transparency

updated previous post with example

user0 wrote: Fri Feb 03, 2023 2:08 pm TweakPNG allows to edit alpha channel of individual color.

yes but not supported by XnView

it would be handy to have such support one day