How to measure spectral signature fro image analysis?

drsunil2424

I would like to know if there is any way to find out spectrum (spectrum signature)from image processing through image pro premier?
Thanks
Sunil

YuriG

Do you mean optical spectrum? How does your image look like? Is it just a picture or spectrum (from prism or diffraction grating)? Note, that normal pixel just contains RGB values, which are the results of compositions of multiple spectra: light source, optics, material, sensor.

Yuri 

drsunil2424

Hi Yuri

Thanks for your quick reply. I have no image processing background, but learning myself for one of our study through image pro premier. Images are of grey scale not RGB and we are looking for optical spectrum and pixel intensity. Herewith I am describing image acquisition and sending off some of our images to better assist us.

Image Acquisition

 We takes  multiple images of retina (which is the light sensitive tissue lining the back of our eye) using con focal laser scanning retinal camera at 30 degree field of view from each eye. The photographs are taken under two modes.

1)    Infrared (IR mode) ( Wavelength 780 nm) captured without any barrier filter

2)    Auto fluorescence mode: (Wavelength 488 nm) captured with barrier filter which blocks all waves under 500 nm allows 500-560 nm

These photographs will be taken at  pre (baseline) and post ingestion of  oral florescent agent and then analyse for changes.

Please see  attached images from our camera for your review.

It would be great if you could outline how we can study pixel and spectrum variation at each point/white spotted areas on given images in terms of intensity and spectrum changes and suggest ways to use some of  image pro premier tools for analysis.

Please let me know you need any further information.

Thanks very much

Sunil

 

YuriG

Hi Sunil,

If you take images with 2 fixed wavelength than you can get only spectral parameters of these 2 wavelength, not whole spectrum.
What you can do in Premier is to combine them to a color image that can be used in further analysis.
Steps:
1. Convert both images to Mono 8bpp.
2. Activate Composite view (Adjust tab, Composite button).
3. Add 2 images to composite view. 
You can assign proper tint or wavelength to every channel and adjust alignment (original images are shifted).
The result should look similar to the attached screenshot.

Regards,

Yuri

drsunil2424

Hi Yuri,

Thanks for your feedback.
I want to ask you if it is possible to calculate spectrum value on the basis of pixel measurement?
Thanks
Sunil. 

YuriG

Yes, you can use arithmetical operations between 2 channels (Calc button on the Process tab), such as Division to calculate relative spectrum value. Note, that this will be spectrum value of the whole system: light source, optics, material and sensor. To get the spectrum value of only the material (retina), you have to first calibrate the system using material with known spectrum.

Yuri