Layers are essentially the backbone of GIMP – with every edit or design happening on some kind of layer. There are image layers, text layers, and layers that contain a background color or just transparency (i.e. don’t contain anything and therefor are totally see-through or transparent). In this GIMP Layers how-to article, which is the first part of a multi-article series, I’ll be showing you how to create a new layer using the “Create a New Layer” dialogue box, and explaining all of the features found in this box.
Creating a New Composition With a Background Layer
For starters, you have to either open an image or create a new composition to be able to do anything with layers. For this example, I’ll simply open a new composition by going to File>New. This will give me the option to create a new image.
Under Image Size (denoted by the red arrow in the photo above), I’ll set the width to 1920 pixels, and my height to 1080 pixels (these are the dimensions for HD). If I click the “Advanced Options” dropdown (denoted by the blue arrow), this will give me even more options.
To keep this tutorial simple, I will keep all of the settings the same. However, I will point out one setting in particular, the “Fill With” setting towards the bottom (denoted by the green arrow in the image above). This setting allows you to determine what type of background layer, which will be the first layer in your composition, you will create when the new image is created. The background layer will always be the same size as the composition size you set up in this step.
If I click the dropdown box for the “Fill With” setting, I get a few options. I can have my background layer color be the same as the current Foreground or Background color I have active (which you can see via the Foreground and Background previews over in the Tool Box), or I can choose pure white, transparency (no background color – just a blank layer), or a pattern (the pattern used will be whatever pattern you currently have active in your patterns dialogue). I’ll choose White as my “Fill With” option and click OK.
I will now have a new composition with dimensions of 1920 by 1080 and a background layer filled with the color white. You can see this layer (denoted by the red arrow in the photo above) in the layers panel, which is the main area where layers are displayed and where their settings are edited (outlined in green and labeled in the photo above).
Creating a New Layer Via the Layers Panel
Once I have a new composition opened in GIMP, I will now have 5 of the 8 total options available (or activated) at the bottom of the layers panel (they were all previously grayed out and therefor unavailable when we first opened GIMP). These options, from left to right and numbered in the photo, include 1.”Create a New Layer,” 2.”Create a New Layer Group,” 3.”Create a Duplicate Layer,” 4.”Add a Mask,” and 5.”Delete This Layer.” (You may have noticed that I skipped over a few icons – the ones that are still grayed out. I’ll get to these a little later on in the series.)
By clicking the “Create a New Layer” icon (denoted by the red arrow), I can add a new layer to my composition on top of the background that was originally created at the start of this tutorial. To understand why this happens, you have to understand what layers are by their simplest definition.
Layers are transparencies stacked on top of one another. This means that you can add multiple layers, one on top of the other, to a composition and have those layers display different colors, images, graphics, text, effects, etc. Items on layers will overlap one another if their pixels take up the same space on the image – and the layers that are higher in the stacking order will be displayed on top of layers that are lower in the stacking order.
Think of layers like sheets of paper stacked on top of one another on a table. If each sheet of paper has a drawing on it, and each of the papers has a random area where some sort of hole was cut out (which represents transparency), you will be able to see the entire drawing on the top piece of paper, and will only be able to see the drawings on the sheets of paper underneath wherever there are holes cut out and the drawings intersect with those holes. In other words, there can’t be anything obstructing your view if you are trying to view drawings below the top-most pieces of paper. The top piece of paper is highest in the stacking order, and the bottom-most piece of paper is lowest in the stacking order.
Once you have clicked the “Create a New Layer” icon, you will now see the “Create a New Layer” dialogue box (shown on the left side of the photo above). This box allows you to customize the settings for your new layer before it is created. In GIMP 2.10 and newer, you have quite a few options for creating a new layer.
Naming Your Layer
For starters, you can rename your layer to basically anything (I named my new layer “Layer 1,” outlined in green above).
This name will show up next to the layer icon in the layers panel after you have finished creating your new layer (as shown in the photo above as an example, denoted by the red arrow).
Adding a Color Tag
Next, you can add a Color Tag to your layer. The Color Tag allows you to keep your layers organized by labeling your layers with colors.
This comes in handy whenever you want to label layers that contain multiple parts to a similar whole (i.e. you are designing a logo that contains multiple shapes, with each shape drawn on its own layer, and you want to label all of the shapes with the same color tag so that you know they all belong to the same element in the logo). In the example photo above, I have a fairly complex composition with multiple layers and layer groups (a concept I’ll get into in another article). Each layer group has its own color tag, and if I expand the layer group you can see that each individual layer within that group shares that color tag.
There are 9 options for selecting a Color Tag (outlined in green in the image above). The first option is to create your new layer with no color tag (the icon is a box with an X through it). The 8 options that follow are the various colors you can set your layer’s Color Tag to. Simply click on any of the colored boxes to select that color as your layer’s color tag. For this example, I went with a green color (the third option from the right).
Setting a Layer Mode
The line below the Color Tag option is labeled “Mode” and contains a dropdown with many options (denoted by the red arrow). This setting allows you to set a blending mode (commonly referred to as layer modes) for your layer. Blending modes allow two layers to interact with one another – usually with the top layer containing the blending mode which then interacts with the bottom layer. These interactions create effects, and the type of effect create depends on the blending mode you set. There are 38 different blending modes in GIMP (that’s more than Photoshop), and each blending mode uses a different equation that plugs in pixel values from the top and bottom layers to create a new, blended pixel value.
By having your Mode set to “Normal,” your layer will act as a normal layer and will not interact, or blend, with the layer below. If you choose any of the other options, your pixels will show up differently depending on what mode you have set and what pixels are on the layer below. I have a video tutorial explaining all 38 layer modes found in GIMP, which I recommend you check out if you want to learn more about layer modes.
This option, as of the time of this article, will always be set to “Auto” and will always be deactivated when creating a new layer. As a result, it is not important to discuss this topic.
Setting a Composite Space
Your “Composite” image is, by its simplest definition, all of the color channels of your image (red, green, and blue) combined together with the transparency of your image (known as the “alpha” channel when discussing transparency in terms of a channel) to form the full-color image or composition you see on your screen. GIMP always uses an RGB color space to display your composite image, as it does not currently support CMYK color spaces (CMYK stands for Cyan, Magenta, Yellow, and Black – which are colors commonly used by printers).
As a result, when you click on the “Composite Space” dropdown, you will see 2 different options – and each option contains some variation of the RGB color space. The two options are “RGB (linear)” and “RGB (perceptual).” Technically speaking, these options are called “channel encodings.” Channel encodings are a complex topic, so all you need to know when it comes to channel encodings is that “RGB (linear)” will display light in your images the way “lightwaves combine in the real world,” whereas “RGB (perceptual)” will display light in your images the way your eyes perceive light. You will almost always get a better result when you select “RGB (perceptual),” and so I strongly recommend going with this option when creating a new layer.
Setting a Composite Mode
To understand the Composite Mode option, you must remember that setting the layer “Mode” will cause the pixels in the top layer to interact with pixels from the bottom layer to create some sort of blended effect. Composite mode takes this concept a step further by determining what elements of these blended layers will be kept when set against a transparent background.
The first option from the dropdown list is the “Auto” option. This option will use the default settings for the layer mode you selected in the “Mode” section (it varies based on each layer mode, though most of them use the Union option, discussed next).
Next, you have the “Union” option. This option is commonly used whenever you have the “Auto” option set for Composite Mode because it keeps the blended pixels from both the top and bottom layers. I should note that, when referring to two blended layers, the top layer is known simply as the “layer” and the bottom layer is known as the “backdrop.”
In the photo above, you can see the top layer (Object 2) is a green circular shape, which I painted with a soft paintbrush. The bottom layer (Object 1), a.k.a. the backdrop layer, is a blue circular shape that is also painted with a soft paintbrush. I set the Object 2 Layer to the layer mode “Overlay” and the Composite Mode to “Union,” and kept the layer mode for the backdrop layer set to “Normal” and the Composite Mode set to “Auto.” As you can see, both objects were kept in the final blended result, creating a light blue area where the two shapes overlap.
The third Composite Mode option is called “Clip to Backdrop.” This mode will only keep all the pixels from the backdrop layer (bottom layer) and any pixels from the top layer that are intersecting with the backdrop layer. All other pixels that were located on the top layer will be “clipped” – or, in other words, deleted. As you can see in the photo above, after I changed the Composite Mode of the Object 2 layer to “Clip to Backdrop,” only the blue object from the Object 1 layer was kept, as well as the lighter blue area where Object 2 intersected with Object 1. Object 2 itself (the green object) has been clipped out of the composition entirely.
NOTE: You can change the composite mode of your layers AFTER you have created them by right clicking on the layer and going to Composite Mode (red arrow in the image above). Once inside this menu, you can select any of the Composite Mode options that were available to you in the Create a New Layer dialogue box.
The fourth Composite Mode option is called “Clip to Layer.” This mode performs the opposite task as the previous mode because it only keeps the pixels from the top layer and any pixels from the backdrop layer that intersect with the top layer pixels. Any pixels that are on the backdrop layer that do not intersect with the top layer will be clipped (deleted). In the example photo above (where I set the Object 2 layer to the Composite Mode Clip to Layer), you can see that only the green object from the Object 2 layer has been kept, along with the lighter blue overlapping area creating by the overlay layer mode (where Object 1 overlapped with Object 2). Object 1 itself (a.k.a. the blue circular object) has been clipped out of the composition.
The last option is the “Intersection” option. This option will only keep the pixels from the top layer and backdrop layer that intersect with one another. Any pixels that do not intersect will be clipped. As you can see in the example photo above (where I set the Object 2 layer to the Composite Mode Intersection), only the light blue area created by the intersection of Object 1 and Object 2 has been kept. Everything else has been clipped out of the composition.
Adjusting Your Opacity
The next option when creating a new layer is the Opacity option. This option uses a slider with values 0 to 100 to determine how transparent (0 is full transparency, or fully see-through) or opaque (100 is full opacity, or fully visible) your layer will display. You can click your mouse on the opacity slider (denoted by the blue arrow) and drag it to the left or right to increase or decrease the value. You can also use the up and down arrows to the right of the slider to make more minute adjustments (denoted by the green arrow), or you can click on the numerical value and manually type in an exact value for your opacity (denoted by the red arrow).
When creating a brand new layer, I recommend starting out with full opacity (100) as you can use the opacity slider in the Layers panel at any time to adjust the opacity of your layers.
Choosing a Width and Height for Your Layer
Underneath the opacity slider is the option to set a width and height for your new layer (outlined in green in the photo above). By default, your layer will be set to the width and height of your background layer (the one we created at the beginning of this article) – which in this case was 1920 pixels by 1080 pixels. You’ll notice a dropdown to the right of the Height value which allows you to set the units for your layer dimensions (denoted by the red arrow). I recommend keeping the units set to the same value as your composition unless you have a specific reason for working with multiple units within the same document.
Although your layer dimensions are set to the dimensions of your background layer (and thus your overall composition size) by default, you can make your layer larger or smaller than your overall composition size. If your layer is larger than your composition (as demonstrated in the example above), the layer boundary will be drawn outside the boundary of your composition (the layer boundary is the yellow dotted line, which you can see goes outside the image window). Any elements displayed in this region will not show up inside the image window or in your final exported file (i.e. if you export it to a JPEG, the parts of the layer boundary that go outside the composition boundary will be clipped).
If you make your layer dimensions smaller than your overall composition size, you will see your layer boundary inside of your composition. Any elements drawn on that layer that go beyond your layer boundary will be clipped.
Offset X and Y Values for Your Layer
Next up is the “Offset X” and “Offset Y” fields (outlined in green in the photo above). These options allow you to offset the position of your new layer once it is created. By default, your layer will be placed in the top left corner on the canvas (even if the layer is larger or smaller than the overall composition size). However, if you don’t want the new layer to be aligned in this way, you can type in an offset value for either the X axis (the axis that goes from left to right on your composition) or the Y axis (the axis that goes up and down on your composition) to customize the position of your layer.
For example, if I type “50” for the Offset X value and “25” for the Offset Y value (as I did in the first photo in this section), when I create my new layer it will be offset 50 pixels to the right of the far left side of my composition and 25 pixels down from the very top of my composition (as you can see in the example photo above – looking at the yellow dotted line where the layer boundary is offset).
Adding a Fill to Your Layer
The last option before you create your new layer is to set a “Fill with” type. You may recall that this was also an option at the beginning of the tutorial when we created a new image. By default, this option will be set to “Transparency,” but you can also click on the dropdown box to select a few other options. “Foreground Color” will fill the entire new layer with whatever color you currently have set as your foreground color. “Background Color” will fill the entire new layer with whatever color you currently have set as your background color. “White” will fill the entire new layer with pure white. “Transparency” will not fill your layer with any color and will make the entire layer see-through (in more technical terms – it will display only the alpha channel and no colors). “Pattern” will fill the entire new layer with whatever pattern you have active (you can set an active pattern in the Patterns dialogue).
If you already have a background layer and intend to paint on your new layer or add any kind of pixel elements (including an image), I recommend setting your “Fill with” type to “Transparency.” This will ensure the background of your new layer will not cover up the original background layer we created earlier.
Check Desired Switches
The last item in the Create a New Layer dialogue box is the “Switches” check boxes (located in a second column to the right of all of the other options we have been working with – outlined in green in the photo above). These options include “Visible,” “Linked,” “Lock Pixels,” “Lock Position and Size,” and “Lock Alpha.”
The Visible option determines whether your layer will be visible or hidden once it is created. This option should be checked to ensure you can actually see your new layer or anything you put on it after it is created.
The “Linked” option enables something called the transform lock feature. This feature allows you to perform the same transformation on multiple layers at the same time using any of the transform tools (i.e. scale, rotate, perspective, etc.). In order for this feature to work, you have to have multiple layers with the “Linked” option enabled.
The “Lock Pixels” option will prevent any new pixels from being drawn on the layer. For example, if you try to paint with the paintbrush tool on a layer with the “Lock Pixels” feature checked, you will get an error message at the bottom of your image window stating “the active layer’s pixels are locked.” This help prevent accidentally drawing pixels on the wrong layer if you have already finished artwork on a particular layer.
The “Lock Position and Size” option allows you to prevent the layer from being moved with the move tool or resized using a transform tool. If you attempt to move pixels on a layer whose position and size are locked via this feature, an error message will display at the bottom of your image window saying “the active layer’s position is locked.”
Finally, you have the “Lock Alpha” option, which allows you to lock the alpha channel or transparency of the layer. If you try to paint anything on the transparent part of your layer, nothing will show up because the alpha channel is locked and cannot be edited. Likewise, if you try to erase existing pixels on your layer and you have an alpha channel on that layer, the eraser will not work because in order to erase pixels you have to be able to edit the alpha channel. If, however, you paint on an area that already had pixels painted, it will indeed paint over that area (though those pixels will still not show up if you try to paint over the alpha channel, or transparent part of the layer).
It is typical when creating a new layer to only have the “Visible” switch checked, and to leave all other options unchecked until they are needed (after you create your layer).
Apply or Cancel Your Changes
Once you have chosen all of your desired settings, click the OK button to create the new layer, or click Cancel if you want to close out the Create a New Layer dialogue without creating a layer.
Your new layer should now show up in the layers panel above the Background layer we created earlier (denoted by the red arrow).