Plant Identification

Home > Other > Plant Identification > Page 35
Plant Identification Page 35

by Anna Lawrence

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).

 

‹ Prev