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Tutorial Gimp Open source image-editing
Gimp
software you can get your teeth into
Gimp: Decay in t
Even experts can learn something new. Michael J Hammel shares his
experiences using a Wacom tablet with Gimp Paint Shop.
of Urban’ by Pierre Fabre of France (www.cgarena.com/
freestuff/tutorials/photoshop/urban/index.html). The
idea is to take a city landscape and add urban decay to the
extreme by integrating elements of water, fire and earth.
In this month’s column I’ll show you how I learned to use
the Wacom Bamboo tablet with Gimp Paint Shop to produce
my own Gimped-up version of the Making of Urban design,
which I call Decay.
The project required five stock images: the city landscape,
two photos of water, one photo of a woman, and one photo of
vines. The final version consists of 73 layers, 51 with layer
masks, and three paths. The total time to produce the final
image was a little over 12 hours.
Most of the work centred on doing hand-drawn blackouts
for windows in the buildings. While I was working on these I
learned that the Detail Brush preset for the Paintbrush and
the Digital Airbrush preset for the Airbrush were the two most
useful configurations provided by Gimp Paint Shop for a
project of this type.
The Wacom Bamboo, Linux and Gimp
Last month we explored a little-known but powerful
feature of Gimp known as Tool Presets. This feature
enables users to configure Gimp for specific purposes
such as simulating pen drawings or working with oils. The
introduction of Gimp Paint Shop, a collection of presets and
associated brushes, is opening up this powerful feature to
more users.
Beginning users usually see Gimp Paint Shop as a tool
used to create drawings from scratch. Advanced users know
this is just the tip of the iceberg. Presets enable you to do
digitally what matte paint artists have done in Hollywood for
years – change the mundane into the extraordinary. Being
the ever inquisitive guy I am, I wanted to see what more I
could do with Gimp Paint Shop. Using the specialised
configurations with a mouse seemed a little hokey. So after
many years of avoiding it, I finally dropped the cash on a
Wacom tablet, a Bamboo model (www.wacom.com/
BambooTablet/bamboo.php). This is the low-end model
from Wacom so I didn’t have high hopes for its quality, but by
the end of this project I was more than pleasantly surprised.
The Wacom Bamboo tablet comes with a small black tablet
with a USB connector and a stylus pen with a holder. The
tablet has four buttons and a circular pad between them at
the top and a 5.8x3.7-inch drawing area below it. Though it
seems small, I found the drawing area completely sufficient
for this project.
The Wacom is recognised out of the box as soon as it is
plugged in with most modern Linux distributions, however it
is not fully functional. Only the stylus side of the pen and the
pen buttons function. To get the other side of the pen (the
eraser side) working, along with the buttons and circular pad,
the xorg.conf file must be updated (details of my specific
Urban dystopia
This project started with two goals in mind:
1 Find out what I can do with the Bamboo tablet.
2 Try to emulate another high-end tutorial.
In this case the tutorial I used for inspiration is called ‘Making
The original city landscape image comes from the stock
photo collection at iStockPhoto.com.
Last month We exposed the hidden treasures of the Gimp Paint Shop.
82 LXF119 July 2009
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Gimp Tutorial
the city
xorg.conf settings
xorg.conf tweaks can be found on the LXFDVD). Once
updated, the X server must be restarted. If you don’t know
how to do this manually, just reboot the machine.
The xorg.conf settings will enable the features of the
Bamboo (or other Wacom tablets) but those features must
then be mapped to keystrokes to be of any use in Gimp.
This is done using the wacomcpl tool. Some distributions
include this in the linuxwacom package (also available at
http://linuxwacom.sourceforge.net), though Fedora 10
does not have a package that includes it. In this case, and
since I’m a Fedora user, the linuxwacom package must be
downloaded and compiled from source.
It’s small, but
as it turns out
you don’t need a
big tablet to do
even very fine
detail work.
Step by step: Unleash hell!
1
Unclutter the skyline
Now it’s time to get down to business. The first
problem with the source photograph is the lack
of background sky: the buildings are too tall and
there are too many cluttered walkways and partial
buildings in the centre of the image.
The height of the buildings is easily fixed by
making a selection of the buildings up through the
top of the sky, copying it and pasting to a new layer.
The new layer is then dragged down to shorten
the perceived height of the buildings. This process
was easy with this photo because the bottom edge
of the selected buildings closely matched their
respective counterparts of the original image so
that there was no apparent seam.
Additional patches of sky were selected and
placed over buildings and walkways in the centre
2
Colour-correct buildings
The next step is to colour-correct the image.
Overall, the original photo was too bright with a
high contrast level. To adjust this I duplicated the
layer in the new cityscape image and desaturated
it. I then used the Levels, Curves, and Brightness-
Contrast dialogs to adjust the desaturated layer.
Then the desaturated layer was moved below the
cityscape layer and that layer’s mode was set to
3
Evil sky
The nearly solid-coloured sky was easy to select
using the Fuzzy Select tool. I added a white layer
mask to the cityscape layer and filled the selection
with black in the mask. I then added several layers
of stock cloud images and arranged them so that
they were below the cityscape layer. Originally I had
painted a sky background using various presets
provided by Gimp Paint Shop, but the result was
of the image. This allows the sky to shine through
the centre area without the buildings cluttering
the view. The whole process required five layers to
shorten the buildings and provide more area for
the sky, and using the original sky for patching will
allow easier selection of the sky later for a mask.
This collection of layers was then flattened to
produce a new cityscape image with no layers. I
should note here that I later added a few more,
small patches specifically to remove flat white
walls on the right of the image.
The bottom edge of the selected buildings
lined up perfectly at their new locations. A series
of patches, including the tall building on the left by
itself, were required to produce the final patched
version (shown here in the bottom-right).
Colour. The results are shown here. The results of
this may not be as obvious in print as they are on
the screen, but reducing the contrast brought out
more details in the image.
Note the missing and misplaced lamp post
lights on the right. This is a result of the shortening
of the buildings that I missed and would not fix
until much later in the project.
too tame. I opted instead for stock images of
clouds that I then flipped (Flip Tool) and whirled
(Whirl and Pinch filter). Colour was added as an
afterthought before the end of the project.
The original painted sky (left) was fun to do and
helped me get a better feel for using the Wacom
tablet, but it just wasn’t menacing enough for what
I had in mind.
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Tutorial Gimp
4
Add building decay
The most-time consuming part
of this project came next: adding
vegetation to the buildings and
breaking out windows and walls.
I started by adding to the mask
of the sky on the cityscape layer,
simulating damage to the tops of
distant buildings. I used Gimp’s
Airbrush tool for this, using the
Digital Airbrush preset from Gimp
Paint Shop, and applied varying
pressure with the Wacom stylus.
The damage to the top of
the buildings was just a proof of
concept at this stage. Adding to
this damage actually occurred
later, but it makes sense to talk
about it now. I made rough
selections of each building, copied
and pasted the selection as a new
layer, then deleted the layer’s
contents. This gave me a layer with
bounds at the edges of the building,
in which I used the Paintbrush
(Detail Brush preset) and Airbrush
5
(Digital Airbrush preset) to draw
blackouts of various windows.
Again, this was all experimentation
on my part, so I started this
process on the distant buildings
doing small blackouts, and it
worked well enough to try the
closer buildings. In some sections,
as shown here, I completely
blacked out a block of windows and
then drew in hanging wires, metal
fragments and broken frames
using the Detail Brush preset and a
white foreground colour. I then
went back over those lines with the
same brush but with different
colours with the Paintbrush tool’s
Mode set to Overlay.
These rough blackouts look
better behind the vines I’ll add in
the next section. Later, I revisited
these with the Detail Brush preset
to draw thin lines to simulate
cracks to go with completely
broken out windows.
7
6
Lamp-post fixes
The next step was to patch the
lamp-posts. To get this just right
I made a detailed selection of the
closest lamp-post on the right-
hand side of the original image
using only the Quick Mask tool.
This was very time-consuming
and I had to zoom in close to make
sure I got a good selection. Four
lamp-posts had to be fixed, and
one partial post left over from
shortening the buildings had to
be removed. The removal was
handled by making a selection of
the area to be removed, moving
the selection up slightly in the
original image, then copying and
pasting this as a patch layer. The
patch layer was them moved down
over the offending lamp-post. The
patch is coloured from the original
image while the area that the
patch was applied to is coloured
after I’d colour-corrected the
buildings. This was addressed by
covering the area later with vines
and some building destruction.
With that patch in place, the
copy of the lamp-post from the
original image was pasted into the
image and moved to line up with
the first lamp post on the right. A
layer mask helped blend the patch
into the image, though the colours
are still off.
The lamp-post patch layer
was duplicated and resized
three more times, once each for
the remaining lamp-posts that
required a patch. Each new layer
was moved into position and
blended with a layer mask.
Earth elements
Next came experiments with
vegetation growing on the
buildings. I made a selection from
a stock image of vines and pasted
it into the image as a new layer,
then added a layer mask and used
the Airbrush to mask out random
sections. This layer was duplicated
numerous times with the layer
mask modified, with each layer
higher up on the building getting a
larger area masked out to reduce
the visible plant growth.
A different selection from the
vine source image (upper-middle)
was used for the concrete covering
Flowing water
There were several steps involved
in creating the water effect. First I
made a selection from a stock
image of water, pasted a copy of
the selection into the project
window and moved it just above
the cityscape layer. I then motion-
blurred it vertically, which
essentially removed the foam but
left a nice colour wash in its place.
This was a very large layer, which
enabled me to use the Perspective
tool to closely align the motion-
blurred colour wash with the
street. A layer mask cleaned up
the layer so it visually fit snug
against the edges of the street.
Finally, the Ripple filter added
some distortion to the water.
This water looked glassy, like
it was frozen. There are good
reflections (a lucky result of the
motion blur that has nothing to do
with the cityscape) but the road
beneath it is not distorted.
The same process was repeated
a number of times to darken
the water and add more waves
over the sidewalk and for the
various other buildings. The
pasted selection was also scaled
down so that the vines appear
further away when applied to
distant buildings. In some cases,
an Unsharp Mask was applied to
the pasted selection.
Vegetation was added to only
three buildings, plus the cement
coverings over the sidewalk on
both sides of the image. I could
have added more, but I imagine
that some buildings don’t provide
a good medium for growing
clinging vines.
and ripples, and I realised that
duplicating the road itself and
applying a ripple to it would
remove some of that glassy
appearance of the water.
In order to simulate the
appearance of flowing water I
needed to add water splashing
on the sides of the road. I made
additional copies from the stock
images of water then copied,
resize and positioned them in
the project image. This changed
the water’s appearance, but not
enough to look right.
So I added additional streaks of
white splashes in random places
around the street, made from yet
more copied selections from the
stock water images. Masking
helped blend these splashes into
the water and completely
removed the glassy appearance
of the water. A few splashes on
the sides of the road and some
white streaks in the middle
changed the water from a frozen
pond to a running river.
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Gimp Tutorial
8
Mood
The image up to this point was a
little dark but otherwise provided
no coloured mood – think of the
green tints of The Matrix or the
blue tints of X-Men. The first
change I made was to brighten
the sky and water but not the
buildings. A radial gradient from
white to transparent was used
for this, along with a mask of the
buildings. Above this I added a
transparent layer and drew in white
highlights on parts of the buildings.
9
Above this, another radial
gradient added the yellow glow
that permeates the image. I’m
very fond of autumn colours and
you’ll find them in many of the
images I create.
The highlights in the water
(upper-left) become more evident
with the two layers of white
highlights (lower-middle). But the
mood is set by the yellow glow
(upper-right) that gives the feeling
that the sun is just about to set.
Humanity
Making of Urban has a man
walking with a dog, but the stock
archives I use didn’t provide me
with a decent image of a person
walking away from the camera.
I found an image of a girl but
the image was very bright and
hardly seemed appropriate. I
made an accurate selection, again
using Quick Mask, and copied,
scaled and positioned the girl
in the middle of the street. I had
to play with the Hue-Saturation,
Brightness-Contrast, Levels and
Curves dialogs to darken her up
without losing too much detail
such as the colour of her legs.
I duplicated this layer and
blurred it, placing the duplicate
above the original layer. I duplicate
the layer again but this time
removed the contents of the layer
and replaced it with hand-drawn
highlights, mostly along the left-
hand side of the girl.
The last piece of the human
puzzle comes from two layers
in the water. The first is a bit of
coloured water that gives a very
soft shadow of the girl. This layer
went below the layers of the girl.
Above this shadow layer I copied
in a copy of a splash from a rock
thrown in a pond.
Summary
The end result of this experiment was a
good understanding of how to use my
new Wacom Bamboo tablet (along with
a genuine fondness for how it feels to
use) and a much better under
understanding of how to make use of
the many presets available in Gimp
Paint Shop. Even though I used only a
small portion of those presets, I have a
better appreciation for their potential.
The final image was well received by
those I showed it to, but I can see many
places for improvement. For one, I
realise now that patches need to be
made from the best possible source. In
most cases I made them from the
original image when instead I should
have made them from a copy of the
colour-corrected buildings. Fortunately,
these colour problems hid themselves
beneath vines and mood colouring.
Another issue is purely aesthetic.
The composition of the image is not
nearly as good as the inspirational
source. The picture lacks some of the
depth that Making of Urban gets from
the use of a road angled from left to
right. And of course the blown-out
windows are not as realistic.
Still, as an experiment I’m quite
pleased with the result. My wife thinks I
should sell prints of images like this. I
think anything that lets me play with the
Bamboo and Gimp is a good idea. LXF
Next month After the apocalypse, the phoenix-like rebirth from the flames!
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