hpr-knowledge-base/hpr_transcripts/hpr3250.txt

Episode: 3250
Title: HPR3250: GIMP: Getting Started With Layers
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3250/hpr3250.mp3
Transcribed: 2025-10-24 19:41:14

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This is Haka Public Radio Episode 3254 for Friday the 15th of January 2021.
Today's show is entitled, GIMP, getting started with Leo and his part of the series GIMP.
It is the 220th show of a huker, and is about 16 minutes long, and carries a clean flag.
The summer is mastering the basic tools of Leo and GIMP.
This episode of HBR is brought to you by an honest host.com.
Get 15% discount on all shared hosting with the offer code HBR15.
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Hello, this is Huka, welcoming you to Hacker Public Radio and another exciting episode
in our GIMP series and I want to build on what I did in our last episode about GIMP
where we introduce the idea of layers and build on that by giving you some tools that
are going to help you in working with this.
But first, I want to mention that I have now updated to the current GIMP 2.10, previously
as on 2.8.
Now I'm not going to go back and redo any of my previous tutorials, which are at a pretty
basic level anyway, so there really wouldn't be all that much even worth bothering about.
But from here on in, I should be using something with the latest features, at least until
I fall behind again, which may happen.
Anyway, with 2.10 for me, it opened in single window mode after installation.
That is probably something it picked up from my existing 2.8 installation where I had switched
over to that.
Now I did need to make one change.
It opened in a very dark theme, which I don't like, so I went to edit preferences and
theme to select the system theme, which is the lightest of those ones that are available.
I did note one change in the layout, and that is that the layers dialog, which used to
be on the top right, is now on the bottom right.
Now that said, all of these dialogues are doccable, which means you can click and drag them
in any position you like.
They can be free floating, or you can put them on a different part of the page, whatever
you wish to do.
So with that said, we're going to begin working with layers.
Of course, you could start by making sure the layers tab is open.
All right, again, that's now in GIMP 2.10 is now on the bottom right.
As I said, I'm working with GIMP in single window mode, and if you want to do that, and
it didn't install that way, what you do is you go to the window menu and select single
window mode.
Now, when I open up GIMP Freshly, I take a look at that layers dialog, there's nothing
there.
I haven't created anything yet.
So what would happen is, let's say you create a new image.
So you go to File, New, and create your basic image.
I did, for instance, I did one 640 by 400 image with a white background.
And what happened is, as soon as I created it, I take a look at the layers dialog, and
I see that, yeah, okay, now there's a layer there.
So that layer shows up in the dialog, and it has, there's room for plenty more, obviously,
I've only got the one at this point.
How many layers can you have?
Well, you're really limited primarily by the amount of RAM in your computer.
A GIMP expert would easily create dozens of layers for just one image, and nothing surprising
about that, and I hope as we go through this, we'll at least raise your level a little
bit on this respect.
Now we take a look at how it displays.
The first thing we see, there's an icon of an eye on the left.
And that tells us that this layer is currently visible.
This is a switch.
So you can click on the eye, and the eye goes away, and that makes it invisible, and click
on that spot, and the eye comes back, and it's visible again.
And next to it, there is a representation of the image, a thumbnail, that is simply
a white rectangle, and it says, background, just because I created an image with a white
background, okay?
Now suppose you were going to work on an existing photo, or some image like that, or
just something that was already there.
As soon as you open the photo, a layer will be created.
And again, you're going to see the eye icon.
Then you're going to see a thumbnail of the photo, along with the name of the photo,
and it's picking that up from the file name.
So I picked a photo, and if you want to see what I did, you can go to my website, and
the link is in the show notes, for the page that this is on.
And it was a picture from some years ago of my wife and I at a dinner, and so the file
name is at dinner.jpg.
So maybe not the most creative naming in the world, but it works.
So we've seen how layers get created when you open or create a new image.
What about adding a new layer?
Now if we take a look at the bottom of the layers dialog, there are a number of icons,
and they allow you to create a new layer, or edit one, move them up and down, et cetera.
So the first button is the one for creating a new layer.
If you click on it, you'll get a new pop-up dialog, the new layer dialog, it'll say create
a new layer.
Now you can do a number of things here.
First of all, you can give the layer a name.
This is just an internal thing that will help you to know what each of these layers is.
And so I would say that's probably worth naming your layers as you do it.
I'm going to say something towards the end of this about how you can think about some
of that stuff.
Then there is a color tag that you can.
It's purely optional.
You don't have to.
Now this only affects how it will appear in the layers dialog.
It's purely a tag for convenience.
Now if you select a tag, and so when I did it, I selected the yellow, and created a new
layer, and what I saw was that in the layers dialog where I have the eye icon on the left,
it is now on top of the yellow background.
So it's simply identifying it in the dialog, there's nothing more fancy than that.
This could be useful if you're working with a number of layers and wanted to group them
by type or category.
Now the next thing in the create a new layer dialog is modes.
Now there's 38 of them, and that's a more advanced topic.
So I'm going to skip that one for now.
We're still working at the introductory level.
And then there's a thing called blend space, and that's grayed out, so obviously you can't
do anything there.
Then there's composite space, and that has to do with the way the three color channels,
the red, the green, and the blue are combined.
Leaving this to auto is probably fine for most purposes.
Again, we're just at an introductory level.
So leave that at auto.
Then there's composite mode, and composite mode has to do with how layers combine.
If you look at the options and see something that looks vaguely Boolean, you're on the
right track.
If you want two layers to add their contents together, pick union, or just where they intersect,
choose intersection.
The other two options are to keep all of one image and add in anything that overlaps
from the other image.
Then there's opacity.
Now opacity comes in when you remember that we're thinking of layers like they were a stack
of transparencies.
If something is 100% opaque, nothing below it can be seen.
But as you reduce the opacity, more and more of the layers beneath it will start coming
through.
With and height are by default pulled from the existing layer when you create a new
one.
You could default because 99% of the time that is what you want.
You just want a stack of identically sized layers, but you could change the dimensions
if you wanted.
The fill is by default transparency.
So when you create a new layer, it will by default have a transparent background.
You could also put in a color or a pattern.
Now this is a good default because basically you don't want to have anything more than
one layer in your stack that has a background.
Because if you put it on anything else, it's going to block everything below it.
So most layers are by default going to be a transparent background and you like it
that way.
Now as to the switches, by default, your new layer will be visible, and that kind of
makes sense.
You wouldn't want to create a new layer and have it invisible right off the start.
You create it because you're going to do something.
Now the thing you should keep in mind is that you can change these settings for an existing
layer by simply right clicking on the layer.
That will pop up a dialog that lets you change the properties of the layer.
So you'll see when you do that, the pop up will say edit layer attributes and then there's
blend space, composite space, composite mode, color tag.
So you can go back and revisit all of those if you want.
Now a note at this point about opacity and transparency, because those settings seem
to be two things that are kind of sort of related and they are related, but they do slightly
different things and it's worth understanding the distinction.
Now what does it mean to create a layer that is transparent and also 100% opaque?
Well we're going to understand there really is no contradiction here.
Transparency is the background setting of the layer.
That means that if you draw something on a layer and then stack it on top of another
layer, the drawing will be on top, but the rest of the image will come through from the
bottom layer because of the transparent background.
The same thing if I drop text onto the transparent layer.
Now this is something you do a lot in creating images.
You add some text on a transparent layer and you can play around with the text all you
want and have no effect on the underlying image.
On the other hand, it would affect the text itself.
If the opacity is less than 100%, some of the underlying image from the beneath layer
would come through.
Technically, it would be mixed in by an algorithm, but that's the best way to think about it.
So they're related, but they have distinct effects.
Now when working with layers, it is important to remember that we're thinking of them like
they are sheets of transparent film stacked one on another.
If you've ever worked with transparentsies on an overhead projector, that's the model
I want you to have in mind for some of this stuff.
Now that means that the order in which you put those layers, those sheets, that order
matters a lot.
If you have a layer with a background that is not transparent, it has to be the bottom
layer.
Otherwise, it's blocking everything else.
That is why most layers have transparent backgrounds.
But even so, all of the layers have content on them that might overlay anything beneath
them.
So to keep the order straight, layers will display in top to bottom order and exactly the
order they appear in the layers dialog.
Now, if the layers are not in the order you need them to be in, you can use the up and
down arrows on the bottom to move a layer up or down in the stack.
Remember that the first layer in the layers dialog will be the top layer.
So it may obscure everything underneath it.
And the bottom layer in the layers dialog will be the bottom of the stack.
So if you need an opaque background of some kind, this is where it should go.
If you are creating an image, and let's take a logo as an example of that, that's something
that graphic designer might do very frequently.
You could open a new image, give it a background, draw images on it, add text boxes and so
on until you had a completed image.
And while this would work, I would counsel you not to do it this way.
The better way would be to create a series of layers.
Make the background layer a layer of its own.
Make each image element a layer of its own.
Then add a text layer, maybe even several.
For example, if you're doing a logo for a company that had several different locations,
you could put the address text on its own layer.
And in fact, you could create all of the address layers at once using the i icon to select
which one is visible at any moment.
So if you had three offices, three different layers for just a address text.
And then by selecting which one is visible, you can then export.
And that way you can keep everything in one XCF file.
Remember, that's the native raw format for GIMP.
And then export different, for instance, JPG files as needed for each location.
Or GIF or PNG or whatever.
Now I would suggest that you should probably try to play with this by creating a new image
in GIMP and then creating layers for it.
Put different things on each layer and see how the result changes when you move layers
up and down.
Then turn some layers off by clicking the i icon.
See what that does, then turn them on again and see what that does.
These are all basic skills for working with layers and getting comfortable with them
will help a lot.
So this is a hook up for hacker public radio, signing off, and as always, encouraging you
to support FreeSoftware.
Bye-bye.
You've been listening to Hacker Public Radio at Hacker Public Radio.