Digitisation of grains

 

 

 

 

Macro photography of grains still poses problems of focus and depth of field.
But scanography, simpler and cheaper, allows a good digitalisation of small objects.

Use a CCD flatbed scanner

With a simple flatbed scanner and minimal organization, you can get very good images of most seeds.
Just use a scanner with CCD sensors giving the necessary depth of field (up to 20mm for our application.)
More common multifunction scanners, with CIS or CMOS sensors, struggle to provide enough depth of field.
 

Graph paper background and reduced material

With a graph paper (in millimeters) fixed on the scanner lid, the grains will look as if they are placed on it.
That will give a reference background to appreciate the dimensions of the grains, regardless of the magnification.
A graph paper with blue lines, if available, will give a better contrast.
The equipment is minimal:

• white plates and saucers for inevitable manual sortings,
• wooden toothpicks in order not to scratch the scanner glass,
• ristol paper with some judicious folds to pick up the grains after the scan or spread them on the glass,
• a tea strainer used as a sieve to remove dust and trash,
• small wedges, sometimes helpful to prevent the lid from squeezing or crushing fragile parts
• and some tissues to clean the glass.
  With a little practice, the organization of the site is not very complicated.

Image formats, dimensions, definition and enlargements

Despite its flaws, we keep the JPG format, as the most common format.
Scanning at a maximum resolution of 2400 dpi typically maintains an acceptable image definition.
Just verify on the scanner glass, that the "staging" is well organized, from the detail to the general.
Four successive scans at 2400, 800, 600 and 400 dpi, keeping a 1000x1000 pixel image size, provide the four enlargements.
That will enable the magnification to be changed on the grain page, without using a heavy single image.
You can pass from a wide to a detailed view.
Although the use of the zoom can lead to an imperfect image, it can show some usefull details.

 

Digitilisations have been made with a Canoscan 5600F