Removing a cloud of heat around the solid part


Hello everyone. I am building a 3d model from some infrared layer Images of a part to study the defects inside the part. The part is created layer by layer. The problem is that there are a cloud of heat around the solid part(which is marked as undesired area). The borders of the solid part change in different layers, therefore I cannot crop them(or i should crop one by one). With “threshold” I could not differentiate the heat cloud from solid part(considering the fact that I am an amateur user). Is there a way that I can differentiate between the solid part and the heat cloud? This heat cloud covers my part in 3d model.

Thank you in advance for any help or hint.


Hi @Miro,
These few steps on this image (the original might be much easier to handle) lead to something you might find useful.

run("Subtract Background...", "rolling=50");
run("Enhance Contrast", "saturated=0.35");
run("Apply LUT");
//setThreshold(0, 32);
setOption("BlackBackground", false);
run("Convert to Mask");
doWand(144, 111);


Thank you so much for the quick and great help. I did some Progress, although I am still struggling.

I write the steps as you said with a little detail for other new users like me.

run(“Smooth”); > Process>smooth
run(“8-bit”); >Image>type>8bit
run(“Subtract Background…”, “rolling=50”); Process>Subtract Background
run(“Enhance Contrast”, “saturated=0.35”); Process>Enhance Contrast
run(“Apply LUT”); Image>lookup tables>applyLUT

the original picture is this:

until here the picture becomes like this:

setAutoThreshold(“Default”); Image>Adjust>Auto Threshold
//setThreshold(0, 32);
setOption(“BlackBackground”, false);
run(“Convert to Mask”);

until here it becomes like this:

doWand(144, 111);

I could not use the wand. what should I do with wand? What are 144 and 111?

Thank you again.


You can read about the wand tool here. To answer your question directly, the two numbers you are giving are a pixel location. The wand tool takes the value of that pixel and travels to the right (positive x) until it reaches a pixel of a different value. Then it traces the edge of that color. So if you want to select just the ring, you would need to do two wand selections and then combine them into a composite selection.


Perfect. Thank you for the explanation and the file.