how to remove background from thermal image. i want to remove the background from the image. just want forground image

[DGM]

Like Walter mentions, the distinction between "background" and "foreground" depends on context. Sometimes the features in the image are salient enough that we might be able to guess, but in this case, it's not at all clear.

Is the distinction spatial? If so, where is the boundary? Does the boundary change between images?

Is the distinction a matter of some specific temperature? If so, we'd need more information than a pseudocolor image alone.

Answer 1

[Walter Roberson]

Consider the thermal images of the Parker Solar Probe. The standard operation of the probe is to block out the main disk of the Sun, and record the prominences of the edge of the Sun.

However, a secondary operation of the probe is to ignore the solar disk and the prominences, and look for moving objects -- to search for comets!

Exactly the same image is being used each time, but the interest is shifted. What is foreground for one purpose is background for the other purpose, and likewise what is background for one purpose is foreground for the other purpose.

It follows that it is impossible to automatically filter out background -- because background for one purpose might be foreground for a different purpose. It is impossible to distinguish foreground and background based entirely on the features of an image.

Answer 2

[Amith]

Hi Ashvini,

There are several methods to remove a background. You might find this resource helpful:

http://www.mathworks.com/help/images/examples/color-based-segmentation-using-k-means-clustering.html

For more information on this topic, you can refer to a previously answered question on MATLAB Answers:

https://www.mathworks.com/matlabcentral/answers/155976-how-to-remove-background-from-an-image

Hope this helps!

Answer 3

[Image Analyst]

The first question is why do you want to remove the background? Chances are you don't need to "remove" it but that you just need to define a region of interest mask to say what's the region you're not interested in, and what's the region you're interested in.

See my Image Segmentation Tutorial in my File Exchange:

Image Analyst's File Exchange

It's a generic, general purpose demo of how to threshold an image to find blobs, and then measure things about the blobs, and extract certain blobs based on their areas or diameters.

There is also a thermal image demo there where you can convert an RGB image into an image where the pixel values are the actual temperature in degrees. https://www.mathworks.com/matlabcentral/fileexchange/113995-thermal-image-color-to-temperature?s_tid=srchtitle

The next question is do you have the raw data (values in units of temperature degrees), or do you just have the RGB pseudocolored image. If you have a colorbar you can convert the pseudocolored image into a temperature image. If you don't you can "blacken" the reddish/pinkish background by starting out with the Color Thresholder on the Apps tab of the tool ribbon and then cleaning up with some morphological operations like bwareafilt, imfill, imclearborder, and functions like that.

If you still need more help, reply with answers to the several questions I asked you.