Requested Access to Alpha Channel of DDS images ?

[Nik_2213]

Alpha / Transparency channels are used by 3D modelling apps to eg paste foliage or horizon textures onto rectangular back-drops, make a complex '3D' grid without hi=poly mesh, turn fabric into gauzy tulle, make hair look wispy, make glazing transparent...

Some apps can read this channel directly from DDS or PNG, apply correctly. Some struggle, are not predictable. Some simply do not 'play nice'.

Often is better to extract DDS or PNG Alpha channel as a stand-alone JPG, convert their RGB to JPG, too, have full control...

Perhaps I'm missing a plug-in, but my Irfan View cannot find Alpha channel of a DDS as it can for eg a PNG.

At the moment, I'm doing DDS using XN_View, but its Alpha channel display is an *obscure* facility, far less convenient than Irfan View's equivalent for PNGs.
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I'd like Irfan View to have the same channel functionality for DDS as it does for eg PNG.
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Though unlikely, I'd also like 'batch' tool extended to copy out such Alpha channels from multiple DDS / PNG to eg JPG, auto-renaming by default with an appended A...
Logically, it would 'fail-safe' if an Alpha channel was not available...
Nik

[j7n]

In XnView you can just do Image > Extract channel > Alpha to get the transparency alone. If it worked in IrfanView, it would be a similar menu item. No more/less obscure. You can batch convert from XnView to PNG or TGA to expose the alpha to other programs in 2 different ways.

Both programs apply the alpha channel against the selected background color. But in IrfanView it can't be extracted. It probably has an "exception" for PNG. I think the program should be upgraded to support alpha generally.

Beware than in XnView, last time I looked, there was a color shift when decompressing S3TC formats due to truncation to 16-bit. It is a lossy procedure.

[Nik_2213]

Thank you, j7n.

I agree that XN_View's Alpha display is accessible. ( Okay, okay, so took me a while to find the first time, but I rarely use the app... )
Sadly, I have not yet found a way to streamline work-flow needed to review a ported model's fifty-some DDS textures, save-out Alphas from the sub-set with 'busy' Alpha channels.

XN_View's batch conversion of eg DDS to other formats with RGB+Alpha is definitely a 'Good to Know' facility.

I must agree that Irfan View's support for Alpha channels would benefit from an upgrade.
If this includes batch extraction with eg a default_A suffix, I'd be delighted...
N