Imagination PowerVR SDK Blog

Alpha premultiply issue with latest version of PVRTexToolCL.exe

pvrtextool

#1

No matter what flags I sent in, PVRTexToolCL.exe always premultiplies RGB by alpha in the textures I pass in. This causes valid textures with an all 0 alpha channel to come out as all black.



Note I’m using the -legacypvr flag (since I need the old format, and the new format crashes on my dds textures anyway).



Is there any way to work around this? Ideally I need the same output as the input (i.e. non zero RGB values and all zero alpha channel).


#2

Hi Andreas,



I haven’t seen this issue before - could you post an example showing how you call PVRTexTooLCL? I can use that to investigate this a bit further. Also, if you could provide details of your texture (or better yet, if you could email an example texture to DevTech@imgtec.com) that would be useful.


and the new format crashes on my dds textures anyway).

Could you elaborate on this - is this an issue you're having with PVRTexTool as well?

Thanks,
Tobias

#3

Hey Tobias - I just downloaded the latest PVRTexTool and getting very unstable behavior. This particular crash was worked around by shuffling the command line parameters around. In general the GUI seems much better at doing what I need to do, but unfortunately I need to batch process lots of files and the GUI can’t do that as far as I can tell.



I will provide example data for the other issue I filed (-legacypvr not recognized by the command line tool).


#4

I emailed repro for my most pressing issue (http://forum.imgtec.com/discussion/2455/legacypvr-not-working-on-pvrtextoolcl-exe-works-on-gui#latest) - sorry for creating two posts on this.


#5

Hi Andreas,



No problem, they’re related but separate issues, so two topics is fine :slight_smile:



Let me know if changing your command line arguments to only use new-style parameters changes the issue you’re seeing here at all as well. The whole reason we moved to a new command line interface was due to the instabilities of the old one, so I wouldn’t be entirely surprised if they just went away now that you’ve switched.



Thanks,

Tobias


#6

Yes, using the new style arguments fixes this, and no pre-multiply takes place.