LXF128_tut_gimp.txt

Tutorial Gimp Open source image-editing
Gimp
software you can get your teeth into
Gimp: Product
Geek is Chic! Gimp author Michael J Hammel shows how a little penguin
(and a little bit of Wilber) makes for fine fashionable wear.
The finished product: take some vector art, tart it up with
Gimp, then get it ready for printing.

After nearly two years it is time to draw this latest
incarnation of the Gimp tutorial series to a close. Over
the years, Gimp has evolved from a college project to
a hacker’s toy to a full-fledged production graphics tool for
the masses. Along the way we’ve celebrated the addition of
plugins, the plethora of filters, the magic of layers and the
power of the Toolbox. And even now, as I bring you one last
dance with Wilber, Gimp continues to evolve. Soon we’ll be
able to frolic in the long promised advances of Gegl, the next
generation soul of Gimp. But as Gimp has evolved so to has
the rest of the world. What was once the purvey of mystical
artisans with brick-oven kilns is now nothing more than a
website with design templates. Yes, you too can print on just
about anything. All it takes is a mouse click and a credit card.
Recently my daughter set off for college in the upper
north-west of the United States. She got there with a lot of
Vector art on the web
Tux: http://vector4free.com/vectors/id/360
Equations: www.vectorjungle.com/2008/11/vector-
art-equations-and-graphs
Dialog Bubble: www.bazaardesigns.com/5415-
dialog-bubbles
Wilber: See the Gimp sources, under the docs directory.
hard work on the tennis court and a fortunate scholarship
opening – a little luck never hurts. As a gift for her taking a
financial load off dear old Dad I made a poster of her team
and a coffee mug with photos of the other incoming
freshmen. They were quite the hit (or my daughter was just
being nice, not that it matters either way to me).
So for this last installment of my Gimp tutorials I thought
I’d walk readers through the process of creating a T-shirt
design suitable for any lovable geek in the family. I’ll show you
how loading free vector art doesn’t require you to keep it in
vector format. I’ll also show you how a parametric brush can
be used to simulate a stitching job that only a nerd could love.
What’s in store
This project will use three different vector images from free
vector sites on the internet. It will also use brushes found in
the Gimp Paint Studio (GPS) collection. I’ll show how a really
big brush doesn’t have to stroked to be useful while
illustrating just how much geeks love math. Along the way
you’ll find your favourite big-eyed mascot pulled right from
the source. And in the end, you’ll have a perfectly sized image
ready for printing on to a T-shirt.
As with most of my tutorials you won’t need much more
than basic Gimp knowledge to complete this tutorial; a
familiarity with layers is essential though, as is knowing your
way around the Toolbox and the Tool Options dialog.
Last month We made a face dissolve into hundreds of little squares.
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Gimp Tutorial
design for geeks
Step by step: Create a T-shirt design
1
Designing for print
Many print-to-order sites, such as Zazzle and
CafePress, offer both US and European sites to
reduce shipping costs. Clothing is the most
common type of product, but look for
alternatives such as mugs, bottles and boxes.
Choose a site that offers the type of product
you want to print on and provides templates to
assist in sizing your images. Zazzle and
CafePress can be pricey, so look for discount
cost sites like Printfection.com and speciality
printers like DeckPeck.com.
4
Background box layer
Create a new layer 500p wide by 500p tall.
Click the Foreground Colour box in the Toolbox
and create a light grey colour. Drag the
Foreground Box into the image window to fill
the new layer with the grey. Click the Align tool
in the toolbox, click the white background in
the image window, then hold down Shift and
click on the new layer. Click the Align Centre
and Align Middle buttons in the Tool Options to
centre the new layer in the image window.
2
Vector art sources
Print designs don’t have to be made
completely from scratch. Use stock photos or
integrate some of the free vector art available
from sites like Vecteezy, Bazaar Designs and
VectorJungle. Be certain to check licences of
downloaded artwork if you plan to sell your
products. Gimp will import SVG, EPS and AI
formats without problem. More important:
setting the resolution on import will generate
an appropriate sized version of that artwork,
perfectly suited to your design project.
5
Add a ripple to the box
Increase the Layer Boundary (Layer > Layer
Boundary Size) to 540 pixels square and
centre the layer within the new bounds. Open
the Ripple filter (Filters > Distorts > Ripple). Set
the Period to 200 and the Amplitude to 15,
then apply the filter horizontally. Repeat the
ripple using the same settings vertically. Scale
the layer (Layer > Scale) to 1980x1980. Set the
Lock Transparency box in the Layers dialog for
this layer.
3
Open a template
Open a product template from the print-to-
order site. This project uses the 10x10 T-shirt
template from CafePress. Most templates will
be JPEG images or PDF files sized at the
correct resolution (usually 200dpi but this can
vary) and dimensions. With a 200dpi JPEG, the
10x10 template is 2,000 pixels wide by 2,000
pixels tall. Fit the project to the template
boundaries. Note that the mug template shows
which part of the image will display on various
parts of the mug.
6
Stamp the background
Reset the Foreground colour to black by typing
D in the image window. In the Brushes window
(Windows > Dockable Dialogs > Brushes)
choose the Circle Circuit 2 brush from the GPS
package. Choose the Paintbrush from the
Toolbox. In the Tool Options dialog set the
Mode to Normal, Opacity to 10%, and the
Scale to 8.00. Click once in the centre of the
image window. This effect is intended to be
very subtle against the background.
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Tutorial Gimp
7
Prepare to stitch
8
The Paintbrush at such a large scale will become annoying, so type R
in the image window to switch tools. Duplicate the Background Box
layer (Layer > Duplicate). Name the duplicate layer Stitches and turn
off the Transparency Lock for this layer. Select the entire layer (Ctrl+A)
and cut the selection (Ctrl+X). Clear the selection (Select > None).
9
Apply stitches
10
Choose the Rake Small brush from the Brushes window. This is a
parametric brush, which means the layout of the dots will depend on
the motion of the brush. Set the Spacing to 100 at the bottom of the
Brushes window. Stroke the selection (Edit > Stroke Selection) using
the Paintbrush but do not emulate brush dynamics. Clear the selection.
11
Multiple Wilbers
Add Wilber
Retrieve the Gimp source code and open Wilber.svg. When prompted,
set the resolution to 25. Drag the layer for this window into the project
image window to copy Wilber into the project. Set the layer mode to
Overlay and the Opacity to 50%. Drag a guide from the left ruler out to
1530 pixels. Move Wilber to align with this guide.
12
Desaturate the Wilber layer (Colours > Desaturate) using the Lightness
setting, then duplicate this layer twice. Drag the first copy down along
the guide line to just above the stitches along the bottom edge of the
image window. Drag the second so it sits directly in the middle of the
other two, also on the same guide line, and adjust the opacity to taste.
Outline the stitches
Click on the Background Box layer in the Layers dialog to make it the
active layer. Select the opaque area of this layer (Layer > Transparency
> Alpha To Selection). Shrink the selection by 50 pixels (Select >
Shrink). Click on the Stitches layer in the Layers dialog to make it the
active layer. The outline of the stitches is ready to be traced.
Bring in the penguin
Retrieve the Vector Tux files. The package contains both EPS and
Adobe Illustrator formats. Choose the EPS format. In the import dialog,
set the resolution to 150 and the colouring to Colour. No antialiasing is
required for this image. Make the tux.eps image the active window and
drag its only layer into the project image window. 2
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Gimp Tutorial
13
Tux clean up
14
Move the Tux layer to the left and down, roughly so the right foot and
left hand nearly touch the stitches boundary. Add transparency to this
layer (Layer > Transparency > Add Alpha Channel). Choose the Fuzzy
Select tool from the Toolbox. Click on the white background of this
layer to select it. Type Ctrl+X to cut this layer’s background out of the
layer. Clear the selection.
15
Adjust equations to fit
16
Use the Move tool to centre the equations over the sign the penguin is
holding. Use the Rotate and Perspective tools to stretch the right side to
better fit the sign. Add a white layer mask (Layer > Mask > Add Layer
Mask) to the Equations layer. Set the Foreground to black by typing D in
the image window. With the layer mask active in the Layers dialog, use
the Paintbrush to paint out the equations over the penguin’s beak.
17
Add text to the balloon
Add a speech bubble
Open an appropriate speech bubble from the last of our free vector
packages. Make a selection around the bubble, then Copy the selection
and paste it into the project image window. Convert the floating layer
this creates into a new layer (Layer > New). Name the new layer Dialog
Bubble. Select the white background in this layer and cut it out.
Desaturate the layer. Flip, Rotate and Scale it to fit.
18
Choose the Text tool, click in the image window and type some clever
phrase in the Text Editor window. Use the Move tool to position the text
inside the balloon, with the left-hand side of the text aligned with the left
of the balloon. Choose the Perspective tool from the Toolbox, then click
on the image window to allow editing of the text layer. Drag the control
points so the text stretches to match the perspective of the dialog box.
Insert equations
Open the EPS file from the vector equations package, this time setting
the resolution to 250. Make a selection around the set of equations in
the image. Copy the selection and then paste it into the project image
window. Convert the floating layer this creates into a new layer (Layer >
New). Name the new layer Equations. Set the layer mode to Multiple so
that only the equations show in the image window.
Ready for print
The original template layer should have its visibility turned off so it
doesn’t end up in the printed product. Save the image in the right
format for the print site, making sure that you use PNG, TIFF or
another format that supports transparency for this image, as formats
such as JPEG don’t support transparency. Finally, upload the image to
the print site. Now just wait for the box to arrive in the post! LXF
www.tuxradar.com
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