Using
GIMP to Increase Business Productivity
Dr.
Amartya Kumar Bhattacharya
BCE
(Hons.) ( Jadavpur ), MTech ( Civil ) ( IIT Kharagpur ), PhD ( Civil
) ( IIT Kharagpur ), Cert.MTERM ( AIT Bangkok ), CEng(I), FIE,
FACCE(I), FISH, FIWRS, FIPHE, FIAH, FAE, MIGS, MIGS – Kolkata
Chapter, MIGS – Chennai Chapter, MISTE, MAHI, MISCA, MIAHS, MISTAM,
MNSFMFP, MIIBE, MICI, MIEES, MCITP, MISRS, MISRMTT, MAGGS, MCSI,
MIAENG, MMBSI,
MBMSM
Chairman
and Managing Director,
MultiSpectra
Consultants,
23,
Biplabi Ambika Chakraborty Sarani,
Kolkata
– 700029, West Bengal, INDIA.
Businesses
that restrict themselves to proprietary software like Microsoft
Office and Adobe Photoshop get a raw deal. Not only do they have to
pay for the software but they have to factor in the cost incurred
every time the software becomes corrupt. This includes the fee to be
paid to the computer technician to re-install the software. All this
creates a vicious cycle, where costs and delays keep mounting. It
should be the primary aim of every business to develop a system that
automates maintenance to the maximum possible extent.
This
is where open source software like LibreOffce, Apache OpenOffce,
Scribus, GIMP, Inkscape, Firefox, Thunderbird,WordPress, VLC media
player, etc, come in. My company, MultiSpectra Consultants, uses open
source software to the maximum possible extent, thereby streamlining
business processes. It makes updating the software and its
maintenance very easy. The required software can be freely downloaded
from the Internet and updates can also be applied by simply
downloading the latest version of the relevant software. With free
and open source software (FOSS) anyone is freely licensed to use,
copy, study and change the software in any way, and the source code
is openly shared so that people are encouraged to voluntarily improve
the design of the software. This is in contrast to proprietary
software, for which the software is under restrictive copyright and
the source code is usually hidden from the users. The benefits of
using FOSS include lower software costs, higher security and
stability (especially with regard to malware), better privacy
protection and more control over the hardware.
So,
let us take a brief look at a key open source software, GIMP. The GNU
Image Manipulation Program (GIMP) is a free and open source raster
graphics editor used for image retouching and editing, free-form
drawing, resizing, cropping, photo-montages, conversion to different
image formats and more specialised tasks. It is the open source
equivalent of Adobe Photoshop.
GIMP
is primarily developed by volunteers as a free and open source
software project associated with both the GNU and GNOME projects.
Development takes place in a public git source code repository, on
public mailing lists and in public chat channels on the GIMPNET IRC
network. New features are held in public separate source code
branches and merged into the main (or development) branch when the
GIMP team is sure they won't damage existing functions. Sometimes
this means that features that appear complete do not get merged or
take months or years before they become available in GIMP. The
version number used in GIMP is expressed in a major -minor-micro
format, with each number carrying a specifc meaning. The first
(major) number is incremented only for major developments (and is
currently 2). The second (minor) number is incremented with each
release of new features, with odd numbers reserved for in-progress
development versions and even numbers assigned to stable releases.
The third (micro) number is incremented before and after each release
(resulting in even numbers for releases and odd numbers for
development snapshots), with any bug fixes subsequently applied and
released for a stable version. The user interface of GIMP is designed
by a dedicated design and usability team. GIMP itself is released as
source code. After a source code release installers and packages are
made for different operating systems by parties who might not be in
contact with the maintainers of GIMP.
The
current version of GIMP works with various operating systems
including Microsoft Windows, Linux and Mac OS. Many Linux
distributions have GIMP as a part of their desktop operating systems,
including Fedora and Debian.
Features
of GIMP
Animation
Showing Brushes, Patterns, Gradients Created in GIMP
Tools
used to perform image editing can be accessed via the toolbox,
through menus and dialogueue windows. They include filters and
brushes, as well as transformation, selection, layer and masking
tools.
Colour
There
are several ways of selecting colours, including palettes, colour
choosers and using an eyedropper tool to select a colour on the
canvas. The built-in colour choosers include RGB/HSV selector or
scales, water-colour selector, CMYK selector and a colour-wheel
selector. Colours can also be selected using hexadecimal colour codes
as used in HTML colour selection. GIMP has native support for indexed
colour and RGB colour spaces; other colour spaces are supported using
decomposition where each channel of the new colour space becomes a
black-and-white image. CMYK, LAB and HSV (hue, saturation, value) are
supported this way. Colour blending can be achieved using the Blend
tool, by applying a gradient to the surface of an image and using
GIMP's colour modes. Gradients are also integrated into tools such as
the brush tool, when the user paints this way the output colour
slowly changes. There are a number of default gradients included with
GIMP; a user can also create custom gradients with tools provided.
Gradient plug-ins are also available.
Selections
and paths
GIMP
selection tools include a rectangular and circular selection tool,
free select tool, and fuzzy select tool (also known as magic wand).
More advanced selection tools include the select by colour tool for
selecting contiguous regions of colour—and the scissors select
tool, which creates selections semi-automatically between areas of
highly contrasting colours. GIMP also supports a quick mask mode
where a user can use a brush to paint the area of a selection.
Visibly this looks like a red coloured overlay being added or
removed. The foreground select tool is an implementation of Simple
Interactive Object Extraction (SIOX) a method used to perform the
extraction of foreground elements, such as a person or a tree in
focus. The Paths Tool allows a user to create vectors (also known as
Bézier curves). Users can use paths to create complex selections,
including around natural curves. They can paint (or "stroke")
the paths with brushes, patterns, or various line styles. Users can
name and save paths for reuse.
Image
editing
There
are many tools that can be used for editing images in GIMP. The more
common tools include a paint brush, pencil, airbrush, eraser and ink
tools used to create new or blended pixels. The Bucket Fill tool can
be used to fill a selection with a colour or pattern. The Blend tool
can be used to fill a selection with a colour gradient. These colour
transitions can be applied to large regions or smaller custom path
selections.
GIMP
also provides "smart" tools that use a more complex
algorithm to do things that otherwise would be time consuming or
impossible. These include:
Clone
tool, which copies pixels using a brush
Healing
brush, which copies pixels from an area and corrects tone and
colour
Perspective
clone tool, which works like the clone tool but corrects for
distance changes
Blur
and sharpen tool blurs and sharpens using a brush
Smudge
tool can be used to subtly smear a selection where it stands.
Dodge
and burn tool is a brush that makes target pixels lighter
(dodges) or darker (burns)
Layers,
layer masks and channels
An
image being edited in GIMP can consist of many layers in a stack. The
user manual suggests that "A good way to visualize a GIMP image
is as a stack of transparencies," where in GIMP terminology,
each level (analogous to a transparency) is called a layer. Each
layer in an image is made up of several channels. In an RGB image,
there are normally 3 or 4 channels, each consisting of a red, green
and blue channel. Colour sublayers look like slightly different grey
images but when put together they make a complete image. The fourth
channel that may be part of a layer is the alpha channel (or layer
mask). This channel measures opacity where a whole or part of an
image can be completely visible, partially visible or invisible. Each
layer has a layer mode that can be set to change the colours in the
image.
There
is support for several methods of sharpening and blurring images,
including the blur and sharpen tool. The unsharp mask tool is used to
sharpen an image selectively — it sharpens only those areas of an
image that are sufficiently detailed. The Unsharp Mask tool is
considered to give more targeted results for photographs than a
normal sharpening filter. The Selective Gaussian Blur tool works in a
similar way, except it blurs areas of an image with little detail.
The
latest version of GIMP is GIMP 2.10. GIMP 2.10 is the result of six
years of work that originally focused on porting the program to a new
image processing engine, GEGL. However the new version ships with far
more new features, including new and improved tools, better file
formats support, various usability improvements, revamped colour
management support, a plethora of improvements targeted at digital
painters and photographers, metadata editing and much more including
an updated user interface and initial HiDPI support
One
thing immediately noticeable about GIMP 2.10 is the new dark theme
and symbolic icons enabled by default. This is meant to somewhat dim
the environment and shift the focus towards content.
There
there are now 4 user interface themes available in GIMP: Dark
(default), Grey, Light, and System. Icons are now separate from
themes and both colour and symbolic icons are present, so GIMP can be
configured to have the System theme with coloured icons if the old
look is preferred.
Moreover,
icons are available in four sizes now, so that GIMP would look better
on HiDPI displays. GIMP will do its best to detect which size to use
but one can manually override that selection in Edit > Preferences
> Interface > Icon Themes.
The
ultimate goal for v2.10 was completing the port to GEGL image
processing library started with v2.6 when the optional use of GEGL
for colour tools and an experimental GEGL tool was introduced, and
continued with v2.8 where GEGL-based projection of layers was added.
Now,
GIMP uses GEGL for all tile management and builds an acyclic graph
for every project. This is a prerequisite for adding non-destructive
editing planned for v3.2.
There
are many benefits from using GEGL and some of them can already be
enjoyed in GIMP 2.10.
High
bit depth support allows processing images with up to 32-bit per
colour channel precision and open/export PSD, TIFF, PNG, EXR, and
RGBE files in their native fidelity. Additionally, FITS images can be
opened with up to 64-bit per channel precision.
Multi-threading
allows making use of multiple cores for processing. Not all features
in GIMP make use of that. A point of interest is that multi-threading
happens through GEGL processing, but also in core GIMP itself, for
instance to separate painting from display code.
GPU-side
processing is still optional but available for systems with stable
OpenCL drivers. One can find configuration options for
multi-threading and hardware acceleration in Edit > Preferences >
System Resources.
Another
benefit of using GEGL is being able to work on images in a linear RGB
colour space as opposed to gamma-corrected (perceptual) RGB colour
space.
Here
is what it boils down to: one now have both linear and perceptual
versions of most blending modes. There is now a linear version of the
Colour Invert command. One can freely switch between the two at any
time via Image > Precision submenu. One can choose which mode is
displayed in the Histogram docker. One can apply Levels and Curves
filters in either perceptual or linear mode. When higher than 8-bit
per channel precision is used, all channels data is linear. One can
choose whether the gradient tool should work in perceptual RGB,
linear RGB, or CIE LAB colour space.
Colour
management is now a core feature of GIMP rather than a plug-in. This
made it possible, in particular, to introduce colour management to
all custom widgets: image previews, colour and pattern previews, etc.
GIMP
now uses LittleCMS v2 which allows it to use ICC v4 colour profiles.
It also partially relies on the babl library for handling colour
transforms since babl is simply up to 10 times faster than LCMS2.
Eventually, babl could replace LittleCMS in GIMP. GIMP now ships with
two groups of blending modes: legacy (perceptual, mostly to make old
XCF files look exactly as before) and default (mostly linear).
New
blend modes are:
LCH
layer modes: Hue, Chroma, Colour, and Lightness;
Pass-Through
mode for layer groups;
Linear
Burn, Vivid Light, Linear Light, Pin Light, Hard Mix, Exclusion,
Merge, and Split.
Layers,
paths and channels can also be tagged with colour labels to improve
project organisation. Compositing options for layers are exposed to
users now and all layer-related settings are finally available in the
Layer Attributes dialogue.
Moreover,
if one always needs alpha in one’s layers, one can enable automatic
generation of the alpha channel in imported images upon opening them.
See Edit > Preferences > Image Import and Export page for this
and more policies. Layer groups can finally have masks on:
Colour
dialogues now have an LCH colour selector one can use instead of HSV.
The LCH selector also displays out-of-gamut warning. A new Hue-Chroma
filter in the Colours menu works much like Hue-Saturation but
operates in CIE LCH colour space. The Fuzzy Select and the Bucket
Fill tools can now select colours by their values in CIE L, C, and H
channels. Both the Colour Picker and the Sample Points dialogue now
display pixel values in CIE LAB and CIE LCH at oner preference.
New
Unified Transform tool simplifies making multiple transforms, such as
scaling, rotating, and correcting perspective in one go.
The
new Warp Transform tool allows doing localised transforms like
growing or shifting pixels with a soft brush and undo support. As
such, the new tool retires the old iWarp filter that was innovative
at the time of its inception (and pre-dated Photoshop’s Liquify
filter), but was ultimately cumbersome to use. The Warp Transform
tool also features an Eraser mode to selectively remove changes,
previously unavailable in the iWarp filter.
The
new Handle Transform tool provides an interesting approach at
applying scaling, rotating and perspective correction using handles
placed on the canvas. People who are used to editing on touch
surfaces might find this tool strangely easy to grasp.
The
Blend tool has been renamed to Gradient tool and its default shortcut
changed to G. But this pales in comparison to what the tool can
actually do now and it is a lot. The new tool pretty much obsoletes
the old Gradient Editor dialogue. Now one can create and delete
colour stops, select and shift them, assign colours to colour stops,
change blending and colouring for segments between colour stops and
create new colour stops from midpoints right on the canvas.
All
gradients available by default are also “editable” now. What it
means is that when one tries to change an existing gradient from a
system folder, GIMP will create a copy of it, call it a Custom
Gradient and preserve it across sessions. Unless, of course, one
edits another ‘system’ gradient, in which case it will become the
new custom gradient.
The
Foreground Select tool can finally make subpixel selections in
complex cases such as strays of hair on textured background. Two new
masking methods are now available for that.
The
Select by Colour and Fuzzy Select tools now both feature a Draw mask
option to display future selection area with a magenta fill and the
latter tool also got a Diagonal neighbours option to select
diagonally neighboring pixels.
For
the Free Select tool, closing a polygonal/free selection now does not
confirm the selection automatically. Instead, one still can tweak
positions of nodes (where applicable), then press Enter, double-click
inside the selection or switch to another tool to confirm the
selection.
The
Intelligent Scissors tool finally allows to remove the last added
segment with Backspace key, and GIMP now checks, whether the first
and the last segments are distinct before closing the curve.
All
colour tools have been refactored to become GEGL-based filters.
Hence, the Colour submenu in the Tools menu has been removed and
these filters are now mostly unavailable in the toolbox.
The
Text tool now fully supports advanced input methods for CJK and other
non-western languages. The pre-edit text is now displayed just as
expected, depending on oner platform and Input Method Engine. Several
input method-related bugs and crashes have also been fixed.
N-Point
Deformation tool introduces the kind of smooth, as little rigid as
possible, warping one would expect physical objects to have.
Seamless
Clone tool is aimed to simplify making layered compositions.
Typically, when one pastes one image into another, there are all
sorts of mismatches: colour temperature, brightness etc. This new
experimental tool tries to adapt various properties of a pasted image
with regards to its backdrop.
To
enable these tools, one needs to first enable the Playground page of
the Preferences dialogue. It is done by running GIMP with a
‘—show-playground.’ switch (for Windows, one might want
tweaking the path to GIMP in the shortcut properties accordingly).
Then one needs to go to Edit -> Preferences -> Playground and
enable the respective options so that the tools would show up in the
toolbox.
GIMP
2.10 ships with a number of improvements requested by digital
painters. One of the most interesting new additions here is the
MyPaint Brush tool that first appeared in the GIMP-Painter fork.
The
Smudge tool got updates specifically targeted at painting use case.
The new No erase effect option prevents the tools from changing alpha
of pixels and the foreground colour can now be blended into smudged
pixels controlled by a new Flow slider, where 0 means no blending.
All
painting tools now have explicit Hardness and Force sliders except
for the MyPaint Brush tool that only has the Hardness slider. GIMP
now supports canvas rotation and flipping to help illustrators
checking proportions and perspective.
A
new Brush lock to view option gives one a choice whether one wants a
brush locked to a certain zoom level and rotation angle of the
canvas. The option is available for all painting tools that use a
brush except for the MyPaint Brush tool.
New
Symmetry Painting dockable dialogue, enabled on per-image basis,
allows one to use all painting tools with various symmetries (mirror,
mandala, tiling…). This new version of GIMP also ships with more
new brushes available by default. Some of the new GEGL-based filters
are specifically targeted at photographers: Exposure,
Shadows-Highlights, High-pass, Wavelet Decompose, Panorama Projection
and others.
On
top of that, the new Extract Component filter simplifies extracting a
channel of an arbitrary colour model (LAB, LCH, CMYK etc.) from the
currently selected layer. If one is used to decomposing and
recomposing images just for this, his work will be easier now.
Moreover, one can now use either darktable or RawTherapee as GIMP
plug-ins for opening raw files. Any recent version of either
application will do. A new Clip Warning display filter will visualise
underexposed and overexposed areas of a photo for one, with
customisable colours. For now, it is mostly geared towards images
where colours are stored with floating point precision. one will
mostly benefit from this if one work on 16/32 bit per channel float
images such as EXR and TIFF.
Plug-ins
GIMP
now ships with over 80 GEGL-based filters. A lot of those are former
GIMP effects. Here is why GEGL-based implementations are better:
One
can apply them on images in 32-bit per colour channel precision mode.
One
can preview them right on the canvas, and if an image is larger than
the viewport, GIMP will render the viewport first for immediate
feedback.
One
can use split preview to compare original image with its processed
version and swap before/after sides both horizontally and vertically.
In
a future non-destructive GIMP, one will be able to adjust settings of
those filters without undoing a ton of steps.
Some
of the GEGL-based filters have OpenCL version for hardware
acceleration. This will come in handy, if OpenCL drivers work well
for one. Furthermore many operations can come multi-threaded to use
oner processor at their full power.
While
working with active users, quite a few usability issues were got rid
of. Here are just some of these changes:
All
transformation tools now automatically disable original layer view so
that one can clearly see adjustments against the backdrop.
Masks
can now easily be created with last values one used by just pressing
Shift and clicking on respective layer’s preview.
All
dialogues except the ones like Scale now remember last values one
used across sessions.
All
GEGL-based filters allow saving named presets and automatically make
timestamped presets for the last time one used them.
One
can now choose fill colour or pattern for empty spaces after resizing
the canvas.
File
formats support
GIMP
is now capable of reading and writing TIFF, PNG, PSD, and FITS files
with up to 32-bit per channel precision where applicable. The PSD
plug-in additionally supports pass-through, hard mix, pin light,
vivid light and linear light blending modes. GIMP now also ships with
native WebP support, including features like animation, ICC profiles,
and metadata. Both importing and exporting are supported. The JPEG
2000 plug-in was rewritten to use the OpenJPEG library rather than
the somewhat obsolete Jasper library. Finally, the PDF plug-in now
supports importing password-protected files (one need to know the
password) and exporting multi-page PDF documents (each layer will be
a page).
Metadata
viewing, editing and preservation
GIMP
now ships with plug-ins for viewing and editing Exif, XMP, IPTC, GPS,
and DICOM metadata. They are available via the Image > Metadata
submenu. GIMP will also preserve existing metadata in TIFF, PNG,
JPEG, and WebP files. Each plug-in has respective options when
exporting to enable or disable exporting the metadata. Additionally,
users now can set defaults to preserving or not preserving metadata
in all affected file format plug-ins at once depending on whether
they want complete privacy or, instead, do a lot of micro-stock
photography. The settings are available on the Image Import and
Export page in Preferences.
On-canvas
interaction
GIMP
2.10 ships with a new feature that allows some GEGL-based filters to
render on-canvas controls. For now, this applies to just three
filters: Spiral, Supernova, and Panorama Projection.
Search
system
As
GIMP keeps growing and getting more features, it becomes increasingly
difficult to locate this or that command in the user interface. This
is especially true when one is a new user who has yet to master image
editing or an experienced user who is accustomed to a different
application. GIMP 2.10 comes with a search system that allows easily
locating a command available in GIMP’s menu. The slash key (/) has
to be pressed, a keyword typed and the command that looks most
applicable choosen.
The
next big update will be v3.0 that will feature GTK+3 port and a lot
of internal changes. For users, this will mostly mean: updated user
interface, better support for graphic tablets, better support for
HiDPI displays, better support for Wayland on Linux.
Image
Formats Overview
Pros
and cons of various images formats from a GIMP perspective
XCF
XCF
is named after the eXperimental Computing Facility where GIMP was
authored.
Pros
The
Native GIMP image format. Everything is saved: layers, selections,
channels, paths and more.
Cons
Not
a “display” format, even if one can find codecs to display
thumbnails of XCF image in file explorers.
Bulky.
Colour
channels are coded in 8 bits (in GIMP 2.8).
Recommended
uses
Saving
all GIMP work.
JPG
Pros
Compresses
the files quite efficiently.
Universally
supported for display.
Cons
Compression
is “lossy” and it slightly alters the image data. In case of
global changes (colour, contrast…) repeated file editing will
slowly degrade the image quality.
At
good quality levels, compression is invisible in photography but can
be seen (so called “artifacts”) in computer-generated graphics
and text.
Does
not support transparency.
Colour
channels are coded on 8 bits.
Recommended
uses
Display
of photography.
Storage
of photography.
PNG
Pros
Lossless
format, all pixels are kept.
Supports
partial transparency.
Produces
small files with most computer graphics.
Supported
by all browsers.
Cons
Complex
images (photos) are bulky.
Colour
channels are coded in 8 bits.
Recommended
uses
Web
page widgets: banners, buttons, frames, etc.
Computer
graphics.
Screenshots
(unless this screenshot contains mostly a photo).
GIF
Pros
Universally
supported for animation.
Cons
Only
256 colours per image, leads to blocky look (a modern variant
supports 256 colours per frame, but GIMP does not use it).
Supports
transparency but only as fully transparent/fully opaque.
Recommended
uses
Small
animated images (in all other still-image uses PNG is a better
alternative, and for bigger animation modern HTML supports video).
TIFF
Pros
Lossless
format, all pixels are kept.
Colour
channels can be coded in 16 bits.
Can
store several images (layers).
Supported
by all image processing software.
Cons
Can
be bulky on complex images.
Recommended
uses
Storage
and exchange of high quality images.
Raw
images formats (NEF (Nikon), CR2 (Canon)…)
Pros
No
loss of information from the camera sensor (in theory).
High-depth
colour channels (12 or 14-bit).
Cons
Proprietary
(except DNG).
Content
format can change without notice (new camera models), this can impact
support by one’s favorite software.
Bulky.
Not
suitable for display.
Recommended
uses
Storage
of camera output but a secondary copy in some universal format could
be a good idea.
There
are of course many other image formats but the formats above cover
most uses. One should use them unless one knows better, they can
usually be converted easily to any other format should the need
arise.
Selling
GIMP
The
terms and conditions for copying, distribution and modification of
GIMP are clearly listed in the GNU General Public License.
Redistribution for free or for profit is specifically allowed as long
as the license is included and the source code is made available.
Besides the rights and conditions given by the GPL, it would also be
nice (but not required) to mention in any advertising that the
product being sold is GIMP (or a bundle including GIMP) or is derived
from it.
Recommendations
for those who sell copies of GIMP
If
you or your company intend to sell GIMP, it would be nice to follow
these guidelines:
Be
honest. Do not try to hide the fact that the product that you are
selling is or contains GIMP (the GNU Image Manipulation Program).
Mention it in any advertisement.
Add
value. Try to provide more than what can be found in the default
GIMP package. Include a nice installer, additional plug-ins, some
nice artwork, some custom brushes and textures, your own tutorials
and documentation, printed copies of the documentation, etc. There
are many ways to add value to GIMP and to make your customers happy.
Respect
the GPL. The GPL requires you to make the source code available.
The best solution is to include the source code on the same medium as
the GIMP installation package, but you can also include a written
offer to supply the source code on request. Note that you cannot
simply give a link to the GIMP ftp mirrors: it should be the exact
source code that was used to compile the binary package that you are
selling and you have to cover the costs of redistribution yourself.
If you sell and distribute the binaries online, the GPL requires you
to make the source code available “from the same place” so giving
a link to the GIMP mirrors is not sufficient.
Support
your users. If the version of GIMP that you are selling is
modified in any way, you should inform your users and try to handle
the support requests related to that version. Providing good support
is another way to make your customers happy.
Finally,
think about giving something back. If the software created by many
volunteers helps your business, it would be nice to return the favour
by helping the developers. You can contribute by sending some
improvements to the code or by sponsoring some events such as the
GIMP developer’s conference. This is not required but happy
developers are more likely to create a better product that you can
sell later.
While
open source software can be obtained free, there are also some issues
involved when using these. One is the frequency of updates, which
depends solely on the developers. Frequent updates are preferred so
that the software remains useful. Another issue is the stability of
the software. Business critical software must be stable and bug-free.
Compatibility with proprietary software used by business partners is
another issue. A company must be able to open a document sent by a
business partner who uses proprietary software.
My
company has developed what it calls the MultiSpectra OS. This
basically consists of Ubuntu Linux with LibreOffce, Scribus, GIMP,
Inkscape, Firefox, Thunderbird and VLC media player.
©
MultiSpectra Consultants, 2019.
