Micrometer to pixels

Highlander · **Joined:** Jan 09, 2018 **Posts:** 17

I am trying to project a selection by using stroke and grow command in Gimp, similar to the picture attached (the image is 200X magnification). I would like to expand about 20 micrometer (uM) but I could only find pixels. So how do I know the amount of pixels required to expand 20 uM?

trandoductin · **Posted:** Mon Jan 15, 2018 8:17 pm **(#2)**

imported your image into GIMP.
used the measure tool to measure from blue line to 70 expansion using 70 line as guide.
it measured about 135 pixels.
so if 135 pixels is about 70um
then 20 um is about 135/70*20 = 38.57 pixels.

Highlander · **Joined:** Jan 09, 2018 **Posts:** 17

trandoductin wrote:

imported your image into GIMP.
used the measure tool to measure from blue line to 70 expansion using 70 line as guide.
it measured about 135 pixels.
so if 135 pixels is about 70um
then 20 um is about 135/70*20 = 38.57 pixels.

Great! Thanks for the quick reply to the post. I really appreciate your help.

Regards,

Highlander

sallyanne · **Posted:** Tue Jan 16, 2018 12:51 am **(#4)**

Got this from https://www.translatorscafe.com/unit-converter/en/
1 micrometer [μm] = 0.00377957517575025 pixel

rich2005 · **Joined:** Mar 04, 2011 **Posts:** 2615

You can of course have any units of length you like defined. There is a provision for this.

https://docs.gimp.org/en/plug-in-unit-editor.html

For microns might be something like this:

One pixel = 264 microns, This is of course a nonsense because Gimp is a raster editor and works in pixels and never forget that.

The dependency is the image resolution, the same 2x2 pix canvas with the resolution set to about 1000 ppi

gives one pixel = 25.4 microns. Which is still nonsense, it is one pixel.

Highlander · **Joined:** Jan 09, 2018 **Posts:** 17

sallyanne wrote:

Got this from https://www.translatorscafe.com/unit-converter/en/
1 micrometer [μm] = 0.00377957517575025 pixel

Hi Sallyanne, thank you very much for the help again.

best regards,

Highlander

Highlander · **Joined:** Jan 09, 2018 **Posts:** 17

rich2005 wrote:

You can of course have any units of length you like defined. There is a provision for this.

https://docs.gimp.org/en/plug-in-unit-editor.html

For microns might be something like this:

[ Image ]

One pixel = 264 microns, This is of course a nonsense because Gimp is a raster editor and works in pixels and never forget that.

The dependency is the image resolution, the same 2x2 pix canvas with the resolution set to about 1000 ppi

gives one pixel = 25.4 microns. Which is still nonsense, it is one pixel.

[ Image ]

Great!! Thanks for the tip. Really appreciate your help.

Regards,

Highlander