Making an image semi-transparent… Or is that semi-opaque?

[HavingTooMuchFun]

(09-27-2018, 12:19 AM)Espermaschine Wrote:

(09-26-2018, 09:48 PM)HavingTooMuchFun Wrote: Why are images that I have made semi-transparent using the opacity control on the layers palette copying or cloning as opaque unless I export and re-import them?

Why are semi-transparent images that are in the clipboard of the brushes palette being applied as opaque?

You can get a transparent clipboard brush from a layer with lowered opacity by using the 'Copy Visible' command.

I know it SEEMS like I should be able to, but that was suggested a little earlier, and I tried it, but it doesn’t work. Could there be some obscure setting that’s at fault here?

Do you know how I can turn off the brushes and get back to using the pencil in the normal way? It’s really getting old having to restart Gimp over and over, LOL!

[Ofnuts]

(09-26-2018, 09:48 PM)HavingTooMuchFun Wrote: FANTASTIC! I experimented a little bit, and by having the “from” color be black or white, almost any color can be made “semi-transparent.” The very few exceptions can also be transformed by adding an infinitesimal amount of black or white, so little that you can’t even see it. Thank you so much for explaining this, this will be a wonderful addition to my artwork!

I’m still struggling with some of the original issues of this post, though:

Why are images that I have made semi-transparent using the opacity control on the layers palette copying or cloning as opaque unless I export and re-import them?

Why are semi-transparent images that are in the clipboard of the brushes palette being applied as opaque?

How do I go from using the brushes palette back to normal pencil function? Currently I’m having to restart Gimp to make that happen.

Edit>Copy copies you layer data, and your layer is opaque.

Warning, pseudo-math ahead.

Layer composition can be seen as an mathematical operator (you have modes like Add, Subtract, Multiply, Divide...), the most frequent operator being "Over" (aka, Normal mode) (often noted ⊕). So basically your "visible" image is computed as:

TopLayer ⊕ Layer2 ⊕ Layer3 ⊕ ... ⊕ LayerN ⊕Background

Which is really computed bottom up, ie:

TopLayer ⊕ (Layer2 ⊕ (Layer3 ⊕ (... ⊕( LayerN ⊕Background)...)))

Layer groups are really just a way to move these parentheses, and so force a different order of composition, for instance making a group with Layers 2 and 3:

TopLayer ⊕ ((Layer2 ⊕ Layer3) ⊕ (... ⊕( LayerN ⊕Background)...)))

That group behaves like another layer, this would be strictly equivalent to computing the group on another image, and then inserting the resulting layer:

Group = Layer2 ⊕ Layer3                              

TopLayer ⊕ (Group ⊕ (... ⊕( LayerN ⊕Background)...)))

So where  does the Opacity slider come in? It is used to add weights/coefficients to the layers (or the groups):

Ot*TopLayer ⊕ (O2*Layer2 ⊕ (O3*Layer3 ⊕ (... ⊕( On*LayerN ⊕ Ob*Background)...)))

But really it does not change the layer's data (which is why you can change it later, if the layer data was changed round-off errors would creep in quickly).

In other words there are two ways for a layer to be transparent: because it is actually transparent (with or without a layer mask) and because you put a small weight on it. If your layer is the only visible on in the image and you set the opacity for it, your visible image is:

Ol*Layer

Which is why Edit>Copy visible copies the layer with its opacity as mentioned by Espermaschine.

[HavingTooMuchFun]

Espermaschine said, "You can get a transparent clipboard brush from a layer with lowered opacity by using the 'Copy Visible' command"... but that's not how it's working for ME. I've tried this with a bunch of different images, and no matter how low the opacity is, the clipboard brush outputs a totally opaque image. Is there some weird setting that's gone wrong here, or some important step that I'm missing?

I'd also REALLY be grateful if someone would tell me how to turn off the brushes and get me back to normal pencil functioning, LOL!

[Blighty]

(09-27-2018, 11:24 AM)HavingTooMuchFun Wrote: Espermaschine said, "You can get a transparent clipboard brush from a layer with lowered opacity by using the 'Copy Visible' command"... but that's not how it's working for ME.

How are you doing Copy Visible? Edit > Copy Visible or something else?

Quote:I'd also REALLY be grateful if someone would tell me how to turn off the brushes and get me back to normal pencil functioning, LOL!

Click on the Pencil Tool in the tool box. Or am I missing something?

[Ofnuts]

(09-27-2018, 11:24 AM)HavingTooMuchFun Wrote: no matter how low the opacity is, the clipboard brush outputs a totally opaque image.

Are you editing color-indexed images (GIF) or plain RGB ones?

[rich2005]

OP did say earlier all was RGB

Quote:...Is there some weird setting that's gone wrong here, or some important step that I'm missing?..

There are no weird settings in Gimp, only the settings you use. It boils down to your work-flow, which probably needs changing. 

Start using transparent layers and stop using color-to-alpha for semi-transparency. 

Compare:



1. The layer is transparent. The opacity is about 40 % the background layer is off. That is what I see. That is what I Copy Visible

2. New transparent layer. Background visibility is back on. Select the clipboard brush. Reset the size (yellow arrow icon next to brush size) Paint in the new layer with semi-transparency. What you need to know here. That new transparent layer is has 100% opacity. The clipboard brush retains the 40% opacity.


Pencil and Brush. You choose either from the tool box, What is the difficulty there? I suspect something else. They do share the same brush shape. Some properties such as brush opacity will change. Up to you to check the settings. No anti-aliasing with a pencil, why do you want to use it?

[Espermaschine]

(09-27-2018, 11:42 AM)Blighty Wrote: How are you doing Copy Visible? Edit > Copy Visible

Yes, thats the one



These threads always follow the same pattern:
some guy downloads powerful open source software and has a specific idea how to do something (which is most of the time not a good technique), but doesnt say what he wants to achieve.
Then chaos breaks loose and OP gets assist over several pages.

First of all: what is the goal ? (brush with fading transparent areas ?)

Solution: 
1. Learn how to make brushes (dont use the clipboard brush for this effect).
2. Learn how a layermask works, then apply knowledge to making a specific brush.

[HavingTooMuchFun]

(09-27-2018, 11:42 AM)Blighty Wrote:

(09-27-2018, 11:24 AM)HavingTooMuchFun Wrote: Espermaschine said, "You can get a transparent clipboard brush from a layer with lowered opacity by using the 'Copy Visible' command"... but that's not how it's working for ME.

How are you doing Copy Visible? Edit > Copy Visible or something else?

Quote:I'd also REALLY be grateful if someone would tell me how to turn off the brushes and get me back to normal pencil functioning, LOL!

Click on the Pencil Tool in the tool box. Or am I missing something?

I was originally doing Edit > Copy, and then per the earlier post I was doing Edit > Copy Visible; both result in opaque images coming from the brushes clipboard.

I’d swear that previously just clicking on the pencil tool was getting me back to normal pencil functioning, but it’s been so long since I used any brushes that I can’t be positive; the only thing I’m positive about is that that isn’t working NOW. 

[rich2005]

Quote:..it’s been so long since I used any brushes that I can’t be positive; the only thing I’m positive about is that that isn’t working NOW..

Try: Edit -> Preferences -> Tools Options then click on Reset Saved Tool Options to Default Values

Click on Ok, restart Gimp see if the pencil tool works. Make sure you are using a valid brush (not an empty clipboard brush)

[HavingTooMuchFun]

(09-27-2018, 12:45 PM)Espermaschine Wrote: These threads always follow the same pattern:
some guy downloads powerful open source software and has a specific idea how to do something (which is most of the time not a good technique), but doesnt say what he wants to achieve.
Then chaos breaks loose and OP gets assist over several pages.

First of all: what is the goal ? (brush with fading transparent areas ?)

Solution: 
1. Learn how to make brushes (dont use the clipboard brush for this effect).
2. Learn how a layermask works, then apply knowledge to making a specific brush.

You’ve got the wrong guy, LOL! First of all, I’m actually not a guy. Secondly, I don’t have a specific idea of how to do pretty much anything, I’m just fumbling around, playing with tools, doing Google searches for articles on tools, and trying to make digital art based on dream images. I just stumbled on the clipboard brush while looking for a way to do something else, and if I can get it to produce a semi-transparent image, I think I can make what I’m trying to make, but I might need to have an image where a part of it is semi-transparent and part of it is opaque… I won’t know until I actually work with it. The end result will hopefully be a flat semi-transparent spiral with a darker area in the middle of the band.

“Learn how“ sounds so simple and reasonable, except I’m a completely non-technical person who can’t make heads or tails out of 99% of the stuff that I find in articles about Gimp. Learning how to do one specific little thing is feasible… although it’s looking like maybe not in this instance… but learning how to do whole complex areas probably isn’t. I’m sorry that this is aggravating to those that are technically proficient!

---

(09-27-2018, 02:31 PM)rich2005 Wrote:

Quote:..it’s been so long since I used any brushes that I can’t be positive; the only thing I’m positive about is that that isn’t working NOW..

Try: Edit -> Preferences -> Tools Options  then click on Reset Saved Tool Options to Default Values

Click on Ok, restart Gimp see if the pencil tool works. Make sure you are using a valid brush (not an empty clipboard brush)

I had high hopes for this one… But sadly, it didn’t work. Pencil worked normally upon restart as it always does. I switched to a brush, verified that it WAS the brush, clicked back on pencil… And it was still the brush. Tried with several other brushes; same thing.