LXF124_tut_gimp.txt

Tutorial Gimp Open source image-editing
Gimp
software you can get your teeth into
Gimp: Summer
Gimp wizard Michael J Hammel lets you ride the retro rave of sunbeams
and silhouettes in this month’s tutorial be-in.
Love in the 60s was black and white, with just a splash of
colour. Or maybe that’s just the rose-tinted specs...
This will be one of the easiest tutorials I’ve presented in
some time – there are no special talents needed here. But
you will need to find some extra brushes to add to Gimp’s
stock collection. I’ll show you were to get these and how to
use them. A stock photo is also required; I’ll point you to the
one I’m using here. Let’s step back in time!

I’m a tail-end baby boomer, which means I was too young
for Woodstock while my parents were too old. They
rocked to Jerry Lee Lewis while I prefer the ‘soft’ melodies
of Pink Floyd or AC/DC. None of us are flower children.
So, in a fond retrospective, my sunbeam tutorial this
month is based on what everyone else has been telling me
the 60s were all about: the sun, beams of light, love and
grassy fields. Somehow I think it was more complex than that.
But not for us. Not this month at least.

Gradients are easy to create and can be used for a
background colour, textured patterns or 3D-like effects.
Creating a custom gradient
The project starts with a splash of colour on the background
applied as a gradient. The easy way to do this is to just set the
foreground and background colours and use the Blend tool
from the toolbox, dragging from top to bottom in the canvas.
Instead, let’s review how to create a custom gradient.
Open a new image (File > New) that’s 1600x1200 pixels.
Type D in the image window to reset the foreground and
background colours to their defaults of black and white,
respectively. At the bottom of the Gradients dialog (Windows
> Dockable Dialogs > Gradients) are icons for managing
gradients. Click on the icon second from the left to create a
new gradient, which will open the Gradient Editor dialog, with
the initial gradient shown using the foreground colour on the
left and background colour on the right. Click and hold the
right mouse button on the gradient to open a menu, then
choose Left Endpoint’s Colour. In the dialog that opens, set
the R, G and B values to 219, 122, and 2 respectively. Click on
OK to set the left endpoint colour.
Creating a custom gradient is all about using that menu to
add new segments, setting the colours on either end of the
segment and adjusting the size of segments. In the Gradient
Editor, change the name from Untitled to “RetroLove” Then
.
click on the Save icon in the dialog, close the Gradient Editor
dialog and choose the Blend tool from the Toolbox. In the Tool
Last month Gimp specialist Michael J Hammel went planetary intergalactic.
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of love	
The reason for having two hills is so that the grassy field
will not be flat or have a uniform curve. These will add a
little variation to the final image.
Options dialog click on the Gradient button and select the
RetroLove gradient. In the image window, drag the top of the
window to the bottom.
Temporary grassy hills
The next step is just as easy. Two small hills will be created
and coloured different shades of green. The colouring is only
temporary, however – later the hills will get a silhouette
treatment when grass is applied to them.
The two hills are created using Ellipse selections in
separate layers. Zoom out on the image (View > Zoom >
Zoom Out). Create a transparent layer (Layer > New) and
name it “Foreground Hill” Use the Ellipse Select tool from the
.
Toolbox and drag a wide oval across the bottom of the image
area. Click on the Foreground Colour box in the toolbox and
change the R, G, B values to 60, 138, and 60 respectively.
Drag the Foreground Colour box into the selection. Clear the
selection (Select > None).
The second hill is created the same way, with the new
layer named “Background Hill” Just offset the selection to the
.
right a little and after applying the colour, use the Brightness-
Contrast dialog (Colours > Brightness-Contrast) to darken
the hill slightly. Move this layer below the Foreground Hill layer
in the Layers dialog. Zoom back in (View > Zoom > Zoom In)
so the layers fit the image window.
Notice that because this layer is behind the hill layers,
the sun appears to be rising (or setting) behind the hills.
Changing the size and position of the selection is possible
in Gimp 2.6 by moving the mouse around the squares that
bound the circle. The middle square is used to move the
selection around, and the top, left, right and bottom change
the width or height of the selection. The corners change width
and height at the same time. The selection will remain
editable until the Enter key is hit or another tool is chosen.
Click on the Foreground Colour box in the toolbox to edit
the colour. Set the R, G, and B fields to 248, 236 and 166
respectively then click on OK to close the dialog and drag the
Foreground Colour box into the image window.
Duplicate the Sun layer (Layer > Duplicate Layer) and
name the duplicate layer “Sun Haze” Open the Gaussian Blur
.
filter (Filters > Blur > Gaussian Blur). Adjust the preview so
the edge of the sun is in view. Set the Blur Radius to 150 for
both the Horizontal and Vertical directions. The Blur Method
should be set to RLE. Hit OK to apply the blur to the Sun Haze
layer and set the Layer Mode for the Sun Haze layer to
For a more
yellow sun, use a
darker colour on
the original Sun
layer then reduce
the opacity of
the Haze layer.
Background sun
Next comes the sun. This will be made from two layers, one
with a solid-coloured sun and another with a soft blur that
makes the sun look just a little hazy.
Add a transparent layer and name it “Sun” Move this layer
.
below the Background Hill layer in the Layers dialog. Choose
the Ellipse Select tool from the toolbox once again. In the Tool
Options dialog, click on the Fixed option to enable it and make
sure the option setting is Aspect Ratio. Drag an oval selection
in the image window and position it so it spans both hills.
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Try to avoid making the initial beam too wide, though
blurs and opacity will help the situation if you do.
Addition. This results in a bright white sun with only a hint of
yellow around the edge.
The retro feel: sunbeams
This next step will add the beams of light emanating from the
sun. It will be easier if you start by zooming out again. Start
with a horizontal beam stretching from the sun to the left
edge. Add a transparent layer named “Sun Beam” and move
it to the top of the stack in the Layers dialog. Click on the left
ruler in the image window and drag a guide to the centre of
the sun. Click on the top rule in the image window and drag to
the same spot. Choose the Paths tool from the toolbox. In the
image window, click just above and just below the intersection
of the guides, then click outside the left edge of the layer
boundary and just below and just above the previous two
points. Next, click on Selection From Path in the Tool Options
dialog and fill the selection with white.
The selection should still be active. Copy (Ctrl+C) and
paste (Ctrl+V) the selection as a new layer (Layer > New).
Use the Flip tool from the toolbox and flip horizontally, then
use the Move tool to position the layer so its left edge aligns
with the intersection of the guides. Duplicate this layer and
rotate it 90 degrees counter-clockwise (Layer > Transform >
Rotate 90 Counter-clockwise). Position this layer so its
bottom edge aligns with the intersection of the guides.
Duplicate this layer and rotate it 45 degrees (Layer >
Transform > Arbitrary Rotation). After rotating, the layer’s
lower-left corner can be aligned with the intersection of the
guides. Duplicate the layer and flip it horizontally, then
position the new layer. Additional beams can be created by
duplicating the vertical or horizontal beams and rotating
them. In some cases the beam will not extend to the edge of
the image, so use the Scale tool to stretch the layer so it does.
To merge the beam layers together, turn off the visibility of
all layers except the beam layers in the Layers dialog, then
merge the remaining visible layers (Image > Merge Visible
Layers). Create a selection from this (Layer > Transparency >
Alpha To Selection). Add a transparent layer and name it “Sun
Beam Gradient” Type D and then X in the image window to
.
set the Foreground colour to white.
Choose the Blend tool from the toolbox. In the Tool
Options set the Gradient to FG to Transparent and the Shape
to Radial. Click in the image window on the intersection of the
guides and drag past the upper-left corner. Turn off the
visibility of the Sun Beam layer in the Layers dialog and turn
on the visibility of the rest of the layers, then move the Sun
Beam Gradient layer below the Sun layer in the Layers dialog.
Open the Gaussian Blur dialog and set the Blur Radius to 20.
Click OK to apply to the Sun Beam Gradient layer.
Lovers’ silhouette
The next element for this project is a stock photo used to
create a silhouette of a couple in love. Look for a photo with a
solid-coloured background – this makes it easier to create a
selection of just the couple. I found the photo used in this
project on the BigStockPhoto.com website.
If the beams are too dim, duplicate the layer and adjust
the Mode and Opacity to taste.
Get a stock photo
This image can be found on BigStockPhoto.com, a low-
cost stock photo website. Alternatives to this image can be
searched for by using the “See Similar Photos” link that
displays to the right of the sample image.
Title: The Friend Throws Up The Girlfriend.
Image ID: 225873 URL: www.bigstockphoto.com/photo/
view/2258753.
The rough selection (left) was improved (right) by using a
small, hard-edged brush (scaled down in the Tool options).
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colours in the Toolbox and then drag the Foreground Colour
into the layer. With the Lock setting for this layer only the
couple is filled with black. Clear the selection (Select > None).
Finishing off the grassy hills
Scaling and flipping may be necessary to position the
silhouette in the most appropriate position on the hills.
This particular photo is well suited for use with the
Foreground Select tool. Choose the tool from the toolbox (it
looks like a head and shoulders with a white ghost behind and
to the right). With the Foreground Select tool active, draw a
freehand selection around the couple. This produces an initial,
rough selection similar to a Quick Mask. Next, select a brush
from the Brushes dialog (Dialogs > Brushes). The brush
should display when you place the mouse over the image
window. In this photo the size of the brush should be no wider
than the woman’s thinnest arm. The size of the brush can be
adjusted using the slider that runs from Small Brush to Large
Brush in the Tool Options dialog.
Paint over the man and woman, covering any places with
high-contrast changes you want to include in the selection.
You don’t have to be exact with this. To complete the
selection, hit the Enter key. This converts Quick-Mask styled
colouring into a selection. Copy (Ctrl+C) and paste (Ctrl+V)
the selection into the original image window as a new layer
and name the new layer “Couple” Scale or flip the layer
.
horizontally if necessary.
Create a selection of the couple in the new layer (Layer >
Transparency > Alpha to Selection). Increase the layer
boundary (Layer > Boundary Size) by 10 pixels for both width
and height. Click on the Centre option to centre the image
within the new layer boundary. Click on Resize to apply the
change to the layer boundary. Then grow the selection (Select
> Grow) by one pixel. In the Layers dialog, lock changes to the
transparent regions of the Couple layer by setting the Lock
button with that layer active. Type D in the image to reset the
The next step is to convert the hills to grassy silhouettes. At
this point you can hide the guides (View > Show Guides) or
remove them (Image > Guides > Remove All Guides). We first
need to change the hills from green to black. One at a time,
select each layer in the Layers dialog and set the Lock button
for it. Grab the Foreground Colour from the Toolbox and drag
it into the layer, just as we did with the couple layer.
Gimp doesn’t come with plant-like brushes suitable for
this project, but there are many collections available for
download online. Once the new brushes are installed, Gimp
must be restarted, so save the project as RetroLove.xcf and
exit (File > Quit). Restart Gimp, open the RetroLove.xcf file
and the brushes will be ready for use.
Many freely available brush collections are created
specifically for Photoshop and are single files with the .abr
filename extension. These files contain multiple brushes.
Gimp can read these files just fine.
Add a transparent layer and name it “Grass” Move this
.
layer to just above the Foreground Hill layer in the Layers
dialog. Open the Brushes dialog (Dialog > Brushes) and
choose an appropriate brush. Set the spacing anywhere from
50 to 150 (smaller if the image size is smaller than the original
1600x1200 used for this project). Choose the Paintbrush
from the toolbox. In the Tool Options dialog, set the Scale
option so the brush outline (place the mouse over the image
window to see this) is an appropriate size. Paint along the
edges of the hills multiple times. Switch to another grass
brush and repeat. Repeat this process until the hills are
sufficiently grassy.
Background birds
The last step is optional but adds a little pizazz to the project.
The trick is to find freely available bird brushes on the
internet. After installing these, save the project and restart
Gimp. Reopen the project file. Add a transparent layer and
name it “Birds” Choose a bird brush, scale it appropriately
.
(smaller for more distant birds) and paint a few blobs around
the sky. If the birds aren’t silhouettes, create a selection of the
birds (Layer > Transparency > Alpha to Selection) and fill the
selection with black. LXF
A few birds
looks like
summer. Too
many will make
it look like an
Alfred Hitchcock
poster though.
This grassy field was created using multiple brushes from
the Grass Brush Set, and appear as a rolling silhouette.
Next month The essential filters that every Gimp artist should know.
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