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Black alpha (RGB+A) transparency?

Dec 7, 2011, 08:47 (This post was last modified: Dec 7, 2011 09:04 by ciider.)
Post: #1
Black alpha (RGB+A) transparency?
Heey so i need some help with making a alpha channel transparency; Funny thing is. I made it work once a few days ago. I went to bed and forgot to write down how i did it (Tried everything, almost)



In the link right here http://www.mediafire.com/?debcev89sv2k77n i have 4 files;
Q3a_arrow_gimp_ver4.tga (TGA that works as i want it, you'll notice ALL the alpha channels have a black layer channel in the channels tab, how do i recreate that?)
Q3a_arrow_methodtry.tga (tried to recreate with THIS tutorial http://www.lucasforums.com/archive/index...26716.html with no success P.S. i tried loooads of tutorials but this recreation seems rather close to the working .TGA i need)
Q3a_arrow.ai (sourcematerial all vector from Adobe Illustrator)
Q3a_arrow.png (picture with transparency intact if needed for comparison)



So; Now... What i did to make the working picture was making a .PNG - drag it into gimp.. I recall doing some Alpha and or masking or selection thing with it, then rendered it for .TGA since Illustrator does not support the kind of .TGA i needed. Worked flawlessly in the engine where i use a function called alphafunc GE128 (blend with black as invisible layer and white as solid)
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Dec 7, 2011, 09:23
Post: #2
RE: Black alpha (RGB+A) transparency?
(Dec 7, 2011 08:47)ciider Wrote:  Heey so i need some help with making a alpha channel transparency; Funny thing is. I made it work once a few days ago. I went to bed and forgot to write down how i did it (Tried everything, almost)



In the link right here http://www.mediafire.com/?debcev89sv2k77n i have 4 files;
Q3a_arrow_gimp_ver4.tga (TGA that works as i want it, you'll notice ALL the alpha channels have a black layer channel in the channels tab, how do i recreate that?)
Q3a_arrow_methodtry.tga (tried to recreate with THIS tutorial http://www.lucasforums.com/archive/index...26716.html with no success P.S. i tried loooads of tutorials but this recreation seems rather close to the working .TGA i need)
Q3a_arrow.ai (sourcematerial all vector from Adobe Illustrator)
Q3a_arrow.png (picture with transparency intact if needed for comparison)



So; Now... What i did to make the working picture was making a .PNG - drag it into gimp.. I recall doing some Alpha and or masking or selection thing with it, then rendered it for .TGA since Illustrator does not support the kind of .TGA i needed. Worked flawlessly in the engine where i use a function called alphafunc GE128 (blend with black as invisible layer and white as solid)
You are pretty close... I think your mistake is that you are not using the same color. Likely you sampled the color (color picker) where it was partially transparent, so you are using a paler color that you try to compensate by using more opacity. Here is how things look when you remove the transparency:
[attachment=768]

To play with the alpha channel of a layer, you use "Layer/Transparency/Add layer mask" (Google tutorials/explanations on "Layer masks"t). What I did above what just painting the mask with white to make a completely opaque patch (it turns out that one pic has RGB=#FFFFFF where it was transparent while the other had RGB=#000000).

Now answering your questions on
https://Gimp-Forum.net
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Dec 7, 2011, 09:57 (This post was last modified: Dec 7, 2011 10:04 by ciider.)
Post: #3
RE: Black alpha (RGB+A) transparency?
(Dec 7, 2011 09:23)ofnuts Wrote:  You are pretty close... I think your mistake is that you are not using the same color. Likely you sampled the color (color picker) where it was partially transparent, so you are using a paler color that you try to compensate by using more opacity. Here is how things look when you remove the transparency:


To play with the alpha channel of a layer, you use "Layer/Transparency/Add layer mask" (Google tutorials/explanations on "Layer masks"t). What I did above what just painting the mask with white to make a completely opaque patch (it turns out that one pic has RGB=#FFFFFF where it was transparent while the other had RGB=#000000).

I think you have found the problem, just confused as how to fix it. I am not sure which alpha layers i need to target ect.
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Dec 7, 2011, 10:15
Post: #4
RE: Black alpha (RGB+A) transparency?
Hmm well I do not think i used layer masks as the Gimp plugin do not handle TGA masks.
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Dec 7, 2011, 10:55 (This post was last modified: Dec 7, 2011 10:57 by ofnuts.)
Post: #5
RE: Black alpha (RGB+A) transparency?
(Dec 7, 2011 09:57)ciider Wrote:  I think you have found the problem, just confused as how to fix it. I am not sure which alpha layers i need to target ect.
Actually you don't need to deal with layer masks:
  • Use the Pointer dialog to measure the RGB values and the opacity of the lines in the original image.
  • Set the foreground color to these RGB values
  • In your target image create a transparent layer.
  • Draw your lines on that layer at full opacity using the foreground color
  • In the Layers list use the opacity slider to reduce the opacity of the layer to the value measured in the first step.
  • Remove or make invisible extraneous layers (default white background for instance) and save.

Now answering your questions on
https://Gimp-Forum.net
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Dec 7, 2011, 11:44 (This post was last modified: Dec 7, 2011 11:56 by ciider.)
Post: #6
RE: Black alpha (RGB+A) transparency?
(Dec 7, 2011 10:55)ofnuts Wrote:  Actually you don't need to deal with layer masks:
[list]
[*]Use the Pointer dialog to measure the RGB values and the opacity of the lines in the original image.
[*]Set the foreground color to these RGB values
Hmm well it is the original image i am building from. So not sure how to do it.

(Dec 7, 2011 10:55)ofnuts Wrote:  [*]In your target image create a transparent layer.
Do you not mean a new layer?

(Dec 7, 2011 10:55)ofnuts Wrote:  [*]Remove or make invisible extraneous layers (default white background for instance) and save.

I need to make it a black background of a sort, plus it does not contain a white background; I never added that in Illustrator: I know this because in Illustrator you need to make a rectangular box.

Edit: i can try and take a screenshot of it. If that helps.
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Dec 7, 2011, 12:08 (This post was last modified: Dec 7, 2011 12:09 by ciider.)
Post: #7
RE: Black alpha (RGB+A) transparency?
http://s471.photobucket.com/albums/rr75/...lip-12.png

http://s471.photobucket.com/albums/rr75/...-46-54.png
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Dec 7, 2011, 13:01 (This post was last modified: Dec 7, 2011 13:16 by ciider.)
Post: #8
RE: Black alpha (RGB+A) transparency?
Edit: wrong message.
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