RGBA with inaccurate "A"


I’m doing some animations that will be integrated on a website and outputting my objects on PNG with Alpha Channel. What happens is that the background area, that should come out completely transparent is turning out with a very slight grey. This makes a square visible around the image. A very dull one, but it’s there.

Anyone knows why this happens and how to fix it in Blender? Of course I could always run a batch in Photoshop to select that and delete, but that’s a far from perfect solution.

this may be a browser problem (i remember something similar in NS6, MSIE doesn’t like PNG’s at all, right?). most browsers still don’t have flawless support for PNG. which one are you using? did you check if the image apperars the same in photoshop, too?

Also, be sure to set ‘Premul’ or ‘Key’ and not ‘Sky’ in Blender Rendering buttons

(Can’t remember wich :slight_smile: )


Internet Explorer doesn’t support PNGs well, especially the alpha channel. I’ve seen some places where you can still get a transparent background to work in IE somehow. You can see it done here on the DS Wiki, another web page I’ve done. I’m not sure exactly but I think that it has something to do with making an <a> element have that as the background image. You just have to force it to be a block element and get it the right size. That seems to do the trick here.

Also, if you are using Photoshop, you should know that it doesn’t properly support PNG either :). Get the SuperPNG plugin here. Photoshop messes up the gamma on PNGs and makes them appear way brighter than they should be. If you are using the GIMP, no problems :).

What is a batch?

I forgot to say the image isn’t supposed to show on html. It’s a flash site and I’m importing a series of keyframes to integrate an animated 3d object on the interface.

S68’s suggestion sounds like something that could solve the problem, I’ll try it ASAP. Thanks man, I’m starting to get used to seeing you solve my problems :smiley:

Jedi Dawn: a batch is a series of commands (select, crop, resize…) that’s automatically applied to a bunch of images. In this case the batch crops the desired portion of each image and saves it.

Can you use batches in gimp?

with scripting you can.

Does that mean that I have to script or that there is already a script?