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Sand scanning methods

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Introduction ^
One way of producing images of a sand sample is to place it on a flat-bed scanner and scan it directly. The results are not as good as a photograph but certainly easier and cheaper. I use an Epson GT-7000 Photo scanner and I find that I can place specimen tubes directly on the glass and scan the sand while it is still inside the specimen tube.

Since the specimen tube is round there is a slight loss in definition at the edges but by using a small scan area you can reduce this to a minimum. I have experimented with making small flat cells using microscope slides. However, the improvement in quality of the scan is not worth the bother of removing a sample from the specimen tube or the risk of spilling sand onto the scanner.

It is difficult to get the colour balance correct and the appearance on screen will depend a lot on the monitor being used. By experimenting with the scanner settings I try to get the colour to appear accurate on my monitor when compared with the actual sample. I find the images look best against a white background.

By scanning at higher resolutions it is possible to get reasonably good enlargements but at the expense of larger file sizes or smaller areas of scan.

Examples are shown below. Some of the images may take a long time to download!


Sample scans ^
 

  
Scan of a complete specimen tube - resolution 72 ppi. - file size 5KB

The same tube scanned at 200ppi - file size 23KB

 

The following images show the effect of scanning a 1cm x 1cm area at increasing resolutions. In each case  the image was saved as a JPG file.


Resolution 72 ppi,  File size - 1KB
(Not enough detail)


Resolution 200 ppi,  File size - 3KB
(Better but still rather small)


Resolution 300 ppi,  File size - 5KB
(Shows fair detail with reasonable file size)


Resolution 400 ppi,  File size - 7KB
(File size getting rather large)


Resolution 720 ppi,  File size - 13KB
(Large file size but good detail for individual display)


Resolution 1200 ppi,  File size - 27KB
(File size too large for normal use)

 

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