garageCube

I export an RGBA image from photoshop with the rgb the same as the alpha.. just black and white with a soft edge.

When I bring it into modul8 and use an alpha mask filiter it seems only the 100% white pixels are transparent... anything between 0 and 1 seems to make a white edge.

any ideas? I'm sure i'm just using the wrong filter or something?

thanks!
bg

you shouldn't need a filter.
it could be your antialias settings... see preference.

it a known bug since years.
a workaround is using aftereffects.
its explained in this thread:
http://www.garagecube.com/forum/viewtop ... ight=alpha

it's not really a bug… it's just metaphysics hehe

your alpha channel and your image are exactly the same which means when the pixels goes from black to white on the alpha, it will make appear the image that is also going from black to white. so it will make appear the greyish pixels in between.
To avoid that, you image should be all black and the alpha as is.

ah, now that makes sense. thanks sigmasix! So you really don't need after effects at all, just make sure your RGB are black in Photoshop. I should have thought of that myself! I didn't think it was actually using the RGB part of the image though.

Side question about mattes...

let's say I have to quickly set up a matte based on two screens on stage. Would a fast way to create two layers, use perspective transforms to match each screen by eye, then export that image(using file> output or something, forget what menu it's under.
Then quickly create an alpha for that in photoshop using that outputted image
THEN
Bring in that image and use it as a mask?

It would be cool if they introduced rotoshapes or something!

Is the 'painter' module reliable?

@barringgaffner from my tests applying this method in Photoshop does not work. Somehow only After Effects can create a clean mask. If you find otherwise please let me know.

its definitly a bug. or lets say a very special behaviour of modul8
in any other program i use, alpha channels were handled different.

a simple test you can make is:
make a image with a mask, which only has black and white inside the alpha
channel. if you use it in modul8, you will get a white greyish border.

use the same mask in other programs, you will not see this white line.
even, if you are not scaling the image.
so come on, it could not be that dificult to interpete an alpha properly

f.

it's not really a bug at all, it does make sense if you think about it. The edge area needs to be the same colour values otherwise the slightly transparent portions will bring through whatever colour is there. although I guess some programs will fix it for you.

ILAN: And yeah, this does indeed work straight from photoshop... no need for After FX!

the RGB channels needs to be black, with the alpha channel being the only one with the mask shape. I had it so that everywhere except the areas I want my video to play through are white and that worked. Now I am only using it to sort of 'look through' a mask so that the video is only projected into certain parts of the stage.. but yes that works. I haven't tried things like logos yet though.

thanks all.

an easy fix in photoshop is to apply image/adjustments/threshold to the alpha channel, which will remove any anti-aliasing.

I´ve got it by simply:

Choose Layer > Matting > Defringe

in ps.

Hmm...thats interesting !!

turn off bi-linear filtering on the media you are using as a mask, this is processing that modul8 applies internally to all media by default to smooth edges.
on an edge of transparency (alpha) the minimum smoothing that can be done is 1 pixel, this is the 1 pixel white line you see.
alternatively, turn the modulateRGB sliders to zero if you want to maintain bi-linear filtering