Is it possible to restore opacity in a semi transparent PNG?

Become a member of the CGSociety

Connect, Share, and Learn with our Large Growing CG Art Community. It's Free!

THREAD CLOSED
 
Thread Tools Search this Thread Display Modes
Old 10 October 2012   #1
Is it possible to restore opacity in a semi transparent PNG?

In Photoshop, through the channels window, I can paint on the R, G and B channels individually. That's great, but where's the Alpha channel? Photoshop only allows me to create a new opacity layer which simply subtracts from the PNG's native opacity - it can't add to it. What I need is to INCREASE opacity.

In other words: I have parts of this PNG which are semi transparent, and I need them to become opaque. How can I do that?

To help explain further, think of it as a single RGBA pixel value. I need to turn (0.5, 0.5, 0.5, 0.0) into this (0.5, 0.5, 0.5, 1.0). Does that make sense?
 
Old 10 October 2012   #2
Maybe I'm not understanding something... but what if you just duplicate the pic a whole bunch of times until the semi-transparent parts become 100%. Then just merge the thing together..?
Also.. If the alpha is 0.0 - doesn't this mean that the pic is invisible?
__________________
-
The Answer to The Ultimate Question Of Life, the Universe and Everything is 42!

http://j2dab.blogspot.com/
dekus.carbonmade.com
 
Old 10 October 2012   #3
Thank you for your reply. Yes, I can duplicate the layer repeatedly, and that will do what I need, though in a very inelegant and ham-handed manner. That's what I've been doing for now.

But just fyi, if a pixel has an alpha of zero, that doesn't necessarily mean its RG and B values are zero. In an ARGB 32 bit PNG file, each channel has its own value. So you could have a pixel that is bright blue, but invisible (0, 0, 0, 255) or a half-visible white pixel (127, 255, 255, 255) for example.

So just because a pixel is "invisible" it doesn't mean it's not there.

Last edited by DubiousDrewski : 10 October 2012 at 09:24 AM. Reason: Grammar
 
Old 10 October 2012   #4
Originally Posted by DubiousDrewski: Thank you for your reply. Yes, I can duplicate the layer repeatedly, and that will do what I need, though in a very inelegant and ham-handed manner. That's what I've been doing for now.

But just fyi, if a pixel has an alpha of zero, that doesn't necessarily mean its RG and B values are zero. In an ARGB 32 bit PNG file, each channel has its own value. So you could have a pixel that is bright blue, but invisible (0, 0, 0, 255) or a half-visible white pixel (127, 255, 255, 255) for example.

So just because a pixel is "invisible" it doesn't mean it's not there.


Neat. Didn't know that..

I would also like to know a more elegant way to restore some semi-transparent object to 100% opacity without it getting all those jagged, artifact-ty outlines that you may see sometimes after piling itself a hundred times then merging together...
__________________
-
The Answer to The Ultimate Question Of Life, the Universe and Everything is 42!

http://j2dab.blogspot.com/
dekus.carbonmade.com
 
Old 10 October 2012   #5
Hmm.. what will happen if you:
- Ctrl-select the semi-transparent object ... to select all of its pixels
- make a new layer under the semi-transparent object
- fill it with.. white?.. black. or something
- now all the needed pixels should have 100% opacity

?
__________________
-
The Answer to The Ultimate Question Of Life, the Universe and Everything is 42!

http://j2dab.blogspot.com/
dekus.carbonmade.com
 
Old 10 October 2012   #6
Ehhhh no. Thanks for the suggestion - that would indeed increase opacity, but it would also dramatically modify the colour to something completely undesirable.

An easy solution I've resorted to: I simply duplicate the layer repeatedly, then collapse it down into a single layer and apply an opacity mask to that. It's very inelegant, but it works.
 
Old 10 October 2012   #7
Originally Posted by DubiousDrewski: Ehhhh no. Thanks for the suggestion - that would indeed increase opacity, but it would also dramatically modify the colour to something completely undesirable.

An easy solution I've resorted to: I simply duplicate the layer repeatedly, then collapse it down into a single layer and apply an opacity mask to that. It's very inelegant, but it works.


ok. you went with the basic technique..
__________________
-
The Answer to The Ultimate Question Of Life, the Universe and Everything is 42!

http://j2dab.blogspot.com/
dekus.carbonmade.com
 
Old 10 October 2012   #8
Layer > Layer Mask > From Transparency
Go into this new layer mask in the channel panel and paint it fully white 255 255 255 and you are done!
__________________
Nightshade UV Editor (script for Maya) - Extends Maya's default UV Texture Editor with additional tools.
 
Old 10 October 2012   #9
Thank you for the suggestion. I forgot to mention that I'm using CS3, and it does not have that feature.
 
Old 10 October 2012   #10
That's unfortunate, because afaik that is the only way you can "break off" the alpha channel of a PNG :/

Install trial version of CS6 and do the change there perhaps?
__________________
Nightshade UV Editor (script for Maya) - Extends Maya's default UV Texture Editor with additional tools.
 
Old 10 October 2012   #11
Thread automatically closed

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.
__________________
CGTalk Policy/Legalities
Note that as CGTalk Members, you agree to the terms and conditions of using this website.
 
Thread Closed share thread



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
CGSociety
Society of Digital Artists
www.cgsociety.org

Powered by vBulletin
Copyright 2000 - 2006,
Jelsoft Enterprises Ltd.
Minimize Ads
Forum Jump
Miscellaneous

All times are GMT. The time now is 06:46 AM.


Powered by vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.