Plant Identification
Page 35
format, and only convert it back to JPEG after you have finished the last ever edit. The quality deteriorates every time you save a JPEG.
•
There is no obvious reason ever to use JPEG format for line drawings.
•
The only reason you might want to use BMP files or uncompressed TIF files is if you have some old software that cannot read other formats. In this case, it may be better to upgrade your software.
•
Some cameras have a native RAW format that professionals use to avoid making JPEGs – the file sizes are very large for JPEGs at the same resolution and they can be awkward to process (to set the white balance manually, etc.). If you are confident handling these files, then you probably do not need to read this. Anyone else should stick to the higher-quality JPEG options from the camera.
See Table 8.3 for a summary of file formats.
210 Plant Identification
Table 8.3 Summary of image file formats
Format
Type
Pros
Cons
Conclusion
JPEG (JPG)
Joint Photographic
Small files for good
Repeated editing and
Use instead of TIF
Expert Group file inter-
images; allows users
saving of files
where size of colour
change format.
to set compromise
introduces increasing,
photographic images
Bitmaps with variable
between file size and
albeit initially subtle,
needs to be minimized
‘lossy’ compression, or
data loss; 1MB file size
artefacts.
– e.g. for large image
24 bit or 48 bit full
can support a >10MB
libraries or
colour images, or
image with no serious
transmission by email.
greyscale.
loss of picture quality.
Not ideal where
‘JPEG 2000’ gives
images are likely to be
even better compres-
repeatedly edited.
sion; commonest
format for photographs
on internet, and
common output from
digital cameras.
TIFF or TIF
Tagged image file
Widely accepted, used
Large file size of colour
Good for line drawings,
format.
and very flexible
images even with
and for archived colour
Bitmap with lossless
format. No information
compression activated.
photo libraries where
(‘LZW’, or no)
is lost every time the
Optional compression
storage space and
compression; 1–48 bit
file is saved. Detailed
settings when saving
transmission space not
images.
line drawings can be
can confuse software
a problem.
compressed to moder-
reading it.
ate file sizes with the
compression option.
BMP
Windows bitmap;
Very standard and
Compression options
A common format, but
1–32 bit.
basic image format for
usually not
not ideal as a photo-
Microsoft bitmapped
implemented, so file
graphic standard
images.
size tends to be unnec-
image format, as the
essarily large.
format is rarely
adopted with its
compressed options
and not favoured
outside Windows.
GIF
Graphic interchange
The main traditional
No good for full-colour
Not really relevant to
format
format of the internet
(>256 colour)
field guide imagery
bitmap.
and other screen
photographs. Some
except where image is
Palette based,
imagery and diagrams
developers do not
to be only computer
maximum 256 colours,
where full colour is not
approve because of a
based.
with lossless compres-
used anyway; single
copyright issue.
sion.
image can be an
animation.
PNG
Portable Network
A new format designed
24 bit image files
Probably a good
Graphics. Bitmap with
for the internet, similar
typically four to five
future-proof solution
lossless compression
to GIF but without
times larger than effec-
for image databases
in 8 bit (256 colour), 24
copyright restrictions
tively identical JPEG.
designed for web use
or 48 ‘true’ colour, or
for software develop-
or otherwise on your
16 bit grey scale.
ers; the 24 bit is more
computer, although at
suitable for photos
the time of writing
than 8 bit or GIF. Some
many users still have
technical improve-
older web browsers
ments over GIFs
and other software that
include slightly better
cannot read it.
compression, variable
transparency (e.g. to
display non-rectangu-
lar images), two-
dimensional interlacing
and gamma correction
(useful for standardiz-
ing brightness on
different computers).
Illustration 211
Table 8.3 continued
Format
Type
Pros
Cons
Conclusion
PDF
Portable document
Good for transferring
Special software
Good for distributing
format.
images and text over
needed to create the
completed, formatted
Adobe Acrobat
the internet; users on
images. Few
guides across the
document format.
different machines and
programmes write this
internet or different
All image types
of the printed output
format directly.
types of computer, and
contained within, with
will see very compati-
for taking your images
text.
ble colours and layout.
to a printer.
EPS
Encapsulated
Related to and similar
Not appropriate for
A standard medium for
postscript.
to PDF format; can be
fully functional
vector-based imagery;
A page description
used for exchanging
document format;
not recommended as a
language. Vector,<
br />
images alone. Widely
different software
general standard for
raster and text.
readable.
tends to treat the files
exchanging your field
slightly differently.
guide images.
Some software can
print, but not display
images imported in
this format.
WMF, EMF
Windows metafile
Convenient way of
Not good for colour
You may well find it
format.
transferring vector and
photographs; not
convenient to use
Enhanced metafile
simple colour images
optimized for bitmap
these formats while
format.
between Microsoft
images.
developing your guide,
Windows metafiles
Windows applications.
especially for graphs,
(24–48 bit colour).
diagrams and other
vector imagery.
DXF
AutoDesk Drawing
Widely adopted
Very large files; vector
If you are stuck trying
eXchange format.
standard for CAD
files only.
to manipulate a vector
drawings.
image, this may be the
format to allow other
packages to read your
file.
PICT
24 bit Macintosh
Standard within
Not much used on
Not widely usable.
picture format.
Macintosh computers
non-Macintosh
for metafiles (raster or
computers.
vector).
Kodak Photo CD.
Standard for storing
Software mostly
If you scan slides to
PCD
scanned images on
cannot write to this
CD, you may receive
CDs.
bulky format.
this format; but it is not
a convenient format for
image manipulation.
Source: William Hawthorne
CONCLUSIONS: CHOOSING AND USING IMAGERY
Real plant specimens can be used as a type of, or in the place of, field guide illustration, as aides mémoires or for reference to repeatedly visited forests – for example, to permanent sample plots. They are ideal for temporary familiarization and standardization of names for small sets of species and small groups of people. For a more permanent solution, a dried leaf specimen guide could be considered; but this is not much use where you have to include either many plants with large leaves (for example, palms), or where identification is to be primarily on aspects other than leaves (for instance, bark and bole guides), or if many people over a large time period might need the guide. Forest or
212 Plant Identification
education institutions might consider mass-producing such field guides for training purposes. The niche for real plant field guides, though, is otherwise limited. Dried plants are hardly practical for use in field guides for which many copies are needed or where more than a few hundred species are to be included. It is probably impossible to include them in a proper publication, for libraries and easy citation. A more standard ‘publishable’ guide, or at least a guide that can be copied, is then needed.
There are not many circumstances in which it is best to use photocopied imagery, standing as it does between the options of using real dried leaves or photographed (or scanned) images. However, if the only tool at your disposal is a photocopier, you may as well try and solve your illustration problems with it, particularly for rare plants of which you have limited real dried leaf material. If you are in charge of a student course or need to perform a local inventory, at short notice, of plants that are recognized largely by their leaves, and you have limited access to equipment, a photocopier as a potential illustrative tool should not disregarded totally – the results are about as accurate as other formats. Colour scanners are marginally better, and enable you to modify and manipulate images. For certain plant groups, where outline shape is the main characteristic to show (for example, many ferns), a scanner can enable a guide to be illustrated very quickly and cheaply.
In general, unless you have a very low budget, or limited requirements for numbers of users and time scale, we recommend concentrating on line drawings and digital photography for a published field guide. If you are a good painter or know one, then by all means use paintings to liven up the book, or the front cover, or for use on publicity material, such as postcards, pamphlets or T-shirts; but the practical work of making accurate plant identification guides is generally served more efficiently by photographs and drawings. Both have their advantages; but consider using a combination of the benefits of drawing (artistic licence to simplify where necessary; cheaper printing) and photography (colour and the illusion of texture).
Digital photography is in the process of revolutionizing tropical field guide production. Black-and-white photographs and images such as line drawings can be created from digital images without much extra effort; so it is possible for a non-artist to create usable diagrams and drawing-like images from pictures of plants, and these will allow printing costs to be reduced considerably – compared to colour photographs, black-and-white line imagery will be about one quarter the cost to print.
Digital photography could be said to have a higher capital cost; manual artwork requires less equipment but requires the services of a competent artist, and the perspecies costs are therefore much more expensive. If the relative values of drawings and photographs were similar, the break-even point, where it would be cheaper for non-artists to buy their own digital camera and equipment, would be somewhere in the range of 10 to 100 species. However, the equation is not so simple, and the main criterion will almost always be: do you want or need photographs, drawings or something cheaper altogether? For a technical audience and cheap compact guides, drawings still have an important niche (see Case study 8.2).
We have based our recommendations in this chapter on the rigorous trials described in Case study 8.1. Illustrations for a field guide should always be tested with groups of potential users, and methods for doing this are described in Case study 8.1
and Chapter 9.
Illustration 213
CASE STUDY 8.2 ILLUSTRATION AND THE WOODY PLANTS OF
WESTERN AFRICAN FORESTS
The Woody Plants of Western African Forests: A Guide to the Forest Trees, Shrubs and Lianes from Senegal to Ghana (Hawthorne and Jongkind, 2006) covers about 2140 species (a few are mentioned in footnotes or the introduction only), 2600 drawings, 2600
photographs, slightly above 1000 pages and 358,000 words. There are more than 4000
species names in the book, including synonyms. Only one species is illustrated with a photograph of a herbarium specimen because it could not be obtained on loan for drawing, and the size of the leaves alone distinguished it from relatives.
This field guide is an output of the European Union (EU)-funded Ecosyn/Ecodes project, with some input from the UK Department for International Development (DFID)–Forestry Research Programme (FRP) Field Guides Project, in terms of the use of many images. It covers trees, shrubs and lianes, as well as many types of non-woody climbers and larger herbs – for example, Marantaceae – that occur in the forest zone of Upper Guinea (West Africa, from Togo to Senegal). This represents more than 75 per cent of the whole Upper Guinean flora, the main groups excluded (15 per cent of the flora) being ferns and orchids, which are distinctive as a group but could justify their own regional field guide, especially as most are epiphytes with wide geographical ranges and are very incomple
tely inventoried. From inception to publication, the guide took ten years. Although all of the contributors have been working on the guide for only a small part (less than 20 per cent) of this time, it has nevertheless taken the four main contributors (excluding project administration) more than 2000 person days of work in total, including two artists to complete the drawings. One of the authors (Carel Jongkind, primarily a taxonomist) concentrated on nomenclatural issues and the taxonomy of some notoriously difficult climber groups, notably the lianes of the Combretaceae, Celastraceae and Annonaceae, while the other (William Hawthorne, primarily a field botanist and ecologist) dealt with the other families, the main structure, linking text, keys and the field characterization. A few genera, notably Pandanus, remain unresolved because someone else is in the process of monographing them, or at least because fertile specimens are far too sparse for us to do so without waiting another five years (by which time many of the other names would have changed again).
The main target users are not taxonomists from developed countries, although we hope such readers will find it useful; rather, they are users with some technical or scientific background in (West) Africa, including foresters of all ranks, wildlife officers, university students, medicinal plant researchers, non-governmental organizations (NGOs) interested in conservation, and hopefully the many plant enthusiasts scattered throughout rural West Africa who are literate, yet have no access to relevant literature. It is hoped that this guide will be a long-term learning tool, as well as a quick reference guide, for these people.
One main task has been to sort out the correct names for all woody plants in the forests of the region, and defining the scope has been a problem in itself. We have adopted a broad span, including thicket and many coastal swamp species in the forest zone, as well as all strictly forest species. Another challenge, especially since Sierra Leone and Liberia have frequently been too dangerous for fieldwork, has been to highlight field characters.
We have been beaten in this aim by a few groups, where reproductive details are therefore used (notably various Annonaceae lianes); but for most of the flora we hope we have substantially facilitated identification for a wide range of users, compared to what could be achieved with existing literature, not least through our copious illustrations. Photographs are used particularly for flowers, fruits and bark or wood details, where colour is generally important or fine details and textures would be hard to draw. The drawings are mainly of
214 Plant Identification
leaves, stems and associated structures, with a significant proportion showing inflorescences without much detail. Where space and images were available, or for recently published species, we have included a few detailed images – for example, of flower cross-sections. Because mistakes and missing information are inevitable for a book of this size, it is supported by extra images and corrections on the Virtual Field Herbarium (see Box 1.1, page 6, and http://herbaria.plants.ox.ac.uk/VFH).