RE: [Histonet] ?s4 electron microscopists

From:"Oshel, Philip Eugene"


There are pros and cons. Film is still higher resolution than digital, with more grey levels, but digital is high enough resolution to produce publishable prints, and getting better. Other choices are to take film images and then digitize them on a flatbed scanner, or to use imaging plates. Imaging plates produces digital images using phosphor-coated plates. The images are equal-equal to film, or are as good as film, but require special scanners, etc. A digital camera is the easiest, and it is faster and cheaper to deal with digital images than to deal with film. Also, there is no expense for darkrooms, darkroom chemicals, and hazardous waste.

Digital images are typically 1 to 4MB (can be bigger), depending on the number of pixels in the acquired image, the bit depth (8-bit or 16-bit for example) and the imaging program. 1024 X 1024 is 1 to 2MB, e.g. Bit depth is usually 8, 12, or 16, but most imaging programs are 8-bit. Some can do 16-bit. The main factor with the imaging program is to be sure it will save images *with* the relevant information (kV, mag, etc.) imprinted on the image *as a TIFF file*, not only as some proprietary format that can only be read by the imaging program. The image must be readable by e.g., Irfanview (shareware for PCs free for non-profit use, rudimentary image processing), Graphic Converter (for Macs, shareware, almost as powerful as Photoshop and easier to use), ImageJ, or Photoshop. Irfanview and Graphic Converter are also file format conversion programs.

A major issue is that digital imaging has no negative. This means that the original image can be manipulated and lost. Even such an innocent thing as changing the brightness and contrast usually changes the actual data. Recall that a digital image is a N x M array of pixels (e.g. 1024 x 1024), each pixed occupied by a number, which represents brightness (intensity). So altering even such basic settings as brightness changes the number, therefore the image. Altering "Levels" changes the *display* of the image, so is a better thing to do.
But what *must* be drilled into people's heads is to burn the data onto a NONrewritable CD *before* doing *anything* to the image. This then becomes the photographic negative, and if a copy is manipulated in any way, the original image is still available unaltered.
People *will* manipulate digital images. It's very easy to do, and doesn't require much if any understanding how the manipulations are done, or what they do to the original images. So greater precautions must be taken to save the original images in an unalterable form.

Emailing files is simple and no big deal. Mind, your Clinic IT people can make it a horrible headache, but I routinely email digital micrographs around the country.
You could also set up a computer as a ftp server on a local network, put the images on that, and let the pathologists download the images from it. Not as convenient as email, but neither will they get lost in emailboxes that they never empty. Plus, the original image is left on the ftp server, and can then be burned to a CD. (Just spend the extra penny to get good CDs! Cheap ones last a few years, good ones are archival.)

Digital cameras for TEMs are generally very expensive, but mostly because the companies have been getting away with the high prices. I'd suggest contacting SIA, Scientific Instruments and Applications:
(I have no business interest in SIA, nor am I a customer, but if I get to digitize our Philips CM-10, SIA is where I'm likely to go. Their prices are much more reasonable for the same quality cameras, and their service reputation is better.)


Philip Oshel
Microscopy Facility Supervisor
Department of Biology
Central Michigan University
Mt. Pleasant, MI 48859
(989) 774-3576

Subject: [Histonet] ?s4 electron microscopists
Dear histonet electron microscopists -

I am currently being trained in to EM to take over for our retiring microscopist. We are building a new lab, and the administration's plan is to go digital. (I have a Zeiss 900 TEM) Are any of you out there using a digital camera on your TEM? What are the advantages and disadvantages? Is the clarity comparable to a darkroom print? The theory is that I will upload my images to my computer, then email them to the pathologists ~ with the huge amount of pixels required, won't this take an awfully long time for the pathologists to download the images?
Any thoughts will be greatly appreciated.
Rita Kenner HTL (ASCP)
Marshfield Clinic
Marshfield, WI

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