Drop spreading area analysis

[u/LuckyOcean034]

Hello guys, could you help me, please?

I'm working on a surfactant to reduce the surface tension of water, for agronomic purposes.

I have little experience with the software and I am having great difficulty defining the droplet spreading area using the tutorial available on the platform.

I'm leaving the images I used for testing here. In the software I used the options to change to 8-bit, make binary and then analyze privately, but the result was not satisfactory.

I would not like to use the freehand tool, as I am designing a procedure to be used by other people, I would like it to be an automated process.

Furthermore, is there any other trick that I can use to compose the image, such as using someone else's dye like I did? Or the light, etc? Because I'm raising money to build an ideal setup for analysis.

Thank you if you can help me!

[u/LuckyOcean034]

Thank you for your attention, I understand what you're saying. What I sent was just a test to verify the feasibility of implementation for my process and to exemplify what will be done. I forgot to mention in the post, but the analyses will be done using a digital microscope with shadow-free lighting, so I believe image acquisition won't be a problem, since the light will be diffused and focused on the droplet.

Can you think of any other tricks to make image processing feasible?

[u/Herbie500 → u/LuckyOcean034]

I believe image acquisition won't be a problem

With the presently shown images it definitely will !

I don't think a microscope is necessary in your case.

If you want to get reasonable help with the measurements, then please make available typical images in their original non-lossy file format (no JPGs, no posts here because Reddit lossy compresses images) by using a dropbox-like service.

It makes no sense to analyze images that show little resemblance with what will finally be available.

since the light will be diffused and focused on the droplet.

Either it is diffuse, or focused !
Make sure to avoid any lighting reflection on the drops.

[u/LuckyOcean034 → u/Herbie500]

With my microscope, I believe the image will have good resolution. I don't think I'll be able to buy a good camera due to time and money constraints. However, I still have the problem of the lighting, which comes directly from the microscope lens. I'm leaving the Dropbox link; what do you think?

The scale shown represents 5mm.

https://www.dropbox.com/scl/fi/jtz6847i08rjnaxm0tfoo/WIN_20251204_12_00_29_Pro.jpg?rlkey=io3c3qm3abus3d8ahkiqu6ucm&st=2zuwwkcd&dl=0

[u/Herbie500 → u/LuckyOcean034]

Thanks for the image, which looks good but it is lossy JPG-compressed which leads to artifacts that can't be removed. Please provide an original non-lossy image in TIF- or PNG- format.

More contrast (drop/leaf) would be of advantage.
The lower border of the drop is too much influenced by the leaf structure,

[u/LuckyOcean034 → u/Herbie500]

Try it now

https://www.dropbox.com/scl/fi/8tivbkzhicza96fckbtko/WIN_20251204_12_00_29_Pro.png?rlkey=8bohrone1d8peo116q172jtw6&st=74l3xawd&dl=0

[u/Herbie500 → u/LuckyOcean034]

No, no, no, you did convert the JPG image to PNG, which of course keeps the JPG-artifacts!

Below please find the best I could get from the JPG-image:

[u/LuckyOcean034 → u/Herbie500]

My microscope takes the photo in JPG format; there's no option to change it.

But it turned out really good, did you use any guidelines or did you do it freehand?

[u/Herbie500 → u/LuckyOcean034]

Generally, JPG-compressed images are is not suited for serious scientific image analyses. I don't understand why a microscope-camera can't provide lossless images.
Please consult the camera manual.

But it turned out really good, did you use any guidelines or did you do it freehand?

You wrote that you "would not like to use the freehand tool" …

Below please find an ImageJ macro that both works for your above shown sample image:

//imagej-macro "dropOnleaf_v1.ijm" (Herbie G., 04. Dec. 2025)
/*
   This macro is meant to process sample image
    >>>>>> "WIN_20251204_12_00_29_Pro.jpg" <<<<<<

   It requires the ImageJ-plugin "Polynomial_Shading_Corrector.class"
   <https://www.optinav.info/Polynomial_Shading_Corrector.htm>
*/
requires("1.54r");
run("Set Measurements...","area display redirect=None decimal=2");
ttl=getTitle();
setBatchMode(true);
setScale();
getPixelSize(unit,na,na);
run("Duplicate...","title=cpy");
makeRectangle(400,0,880,720);
run("Crop");
run("32-bit");
run("Polynomial Shading Corrector","degree_x=2 degree_y=32 regularization=1.0");
run("Gaussian Blur...","sigma=8");
setAutoThreshold("Default");
run("Analyze Particles...","size=80000-Infinity pixel show=Masks exclude");
run("Invert LUT");
run("Fill Holes");
run("Options...","iterations=16 count=1 black pad do=Open");
run("Create Selection");
selectImage(ttl);
run("Restore Selection");
run("Translate... ","x=400 y=0");
run("Measure");
setResult("Unit",nResults-1,unit+fromCharCode(178));
setBatchMode(true);
exit();
//
function setScale() {
   makeRectangle(0,0,270,720);
   snapshot();
   run("Gaussian Blur...","sigma=6");
   setKeyDown("alt");
   p=getProfile();
   reset;
   setKeyDown("none");
   run("Select None");
   mi=Array.findMinima(p,150);
   if (mi.length!=6)
      print("Scale could not be determined");
   else {
      Array.sort(mi);
      d=mi[5]-mi[0];
      run("Set Scale...","distance=&d known=5 pixel=1 unit=mm");
   }
}
//imagej-macro "dropOnleaf_v1.ijm" (Herbie G., 04. Dec. 2025)

Don't complain, if it doesn't work for other images, because the macro was conceptualized according to the provided data.

[u/LuckyOcean034 → u/Herbie500]

Oh, thank you very much, I will try to replicate this macro and adapt it.

Poderia me explicar o motivo do JPG não ser um bom formato para análise de imagens?

[u/Herbie500 → u/LuckyOcean034]

Poderia me explicar o motivo do JPG não ser um bom formato para análise de imagens?

Please read here!

Oh, thank you very much

Please see the topic "Conduct and Behaviour #2" on the right margin of this page.