Measureing an area

Steffen Schmidt sschmid2 at Uni-MolGen.gwdg.de
Mon Jun 14 05:39:15 EST 1999



"David B. Hedrick" wrote:

> Steffen:
>
>         Wow.  What software do you use?
>
>         You could blow up the image, print it out, cut out the cricket wing
> cell, and weigh the piece of paper.  Now, stop laughing, I'm serious.
> Do the same for something you took an EM of and that you know the area
> of to determine the scale.  Cut out and weight 5 copies of the same
> image to determine the variation in your method.  Maybe try different
> types of paper to find one that is constant.  Regular lazer jet paper
> works fine and is cheap.  If this cricket wing business is something
> you're going to do once and quit, this quick and dirty method might get
> you done quicker than something more computerized.
>

Thanks for that straight forward solution :-).
At the moment I am simplifying the image in black and white. Then I measure with
the pick-tool of Corel Photo-Paint the whole picture. The grey-value gives me a
value of 0-255 which I then normalize to 100 %. With the help of the EM-scale I
can determine the size of the wing.
A friend of mine suggested to convert the picture into an ASCII-file with 'xv'
(black-and-white) and then counting the black pixel by the command grep '255'
datei | wc.


>         Or, Visual basic (and almost all other programming languages) will let
> you determine the color of a pixel of a bitmap.  You could use Corel
> Photo-Paint or Paint Shop Pro to simplify the image - 2 color only, and
> use the magic wand to copy the cell to a blank bitmap.  Then a very
> simple program could count the colored pixels.  You could even have it
> color each pixel as it is counted so you can see that it is working
> correctly.
>
>         Or, when you increase the magnification of an image in Paint Shop Pro
> to the maximum, you can clearly see the individual pixels.  You could
> count them yourself.  Use a drawing tool with a color not used in your
> image to mark out each one as you count.
>
>         Or, you could hire someone like, well, like me to do it for you.
>
>         Have fun!
>
> > Hi,
> >
> > I want to measure the size of a cell on a crickets'wing. Therefore I use
> > an EM and save the picture as a bitmap. Has anyone an idea how to
> > measure an area in a bitmap-picture? It would be appreciable when there
> > would be a tool which can automatically select the wanted area - like
> > the magic wand mask tool of Corel Photo-Paint.
> >
> > Thanks
> >     Steffen
> >
> >     ---------------------------------------------------------------
> >
> >                               Name: sschmid2.vcf
> >             Part 1.2          Type: text/x-vcard
> >                           Encoding: 7bit
> >                        Description: Card for Steffen Schmidt
>
> --
>                 ~DBH
>
> Technical writing, literature search, and data analysis at the interface
> of chemistry and biology.
>
>         davidbhedrick at icx.net
>
>         David B. Hedrick
>         P.O. Box 16082
>         Knoxville, TN 37996
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