Salmon

[Hornblende]

Not a live one, I am eating it right now as I write this post.

I love playing with my new flashlights and filters so thought it would be a good idea to do a multispectral of my meal before cooking it, so there it is!

 

 

Gear used:

Camera: Canon 6D full spectrum

Lens: Carl Zeiss Jena Tessart 50mm f/2.8

Filters: Baader-U ; Lifepixel IR 830nm filter ; Baader UV/IR cut filter ; BG-39

Light: Convoy S2+ ; Uniquefire IR 940nm

 

VIS – Tasty right?

 

IR – Not so tasty now, the salmon seems bland..

 

UV – I am not sure if I would eat that, it looks dry..

 

UVIVF – Now I would eat that! The UVIVF shot is clearly the best.

 

UVIIRF – Same as IR, nothing very interesting.

[Hornblende]

I found something interesting. Below are the individual red, green and blue chanels of the VIS image, plus the UV image.

As I expected the red chanel is very similar to the IR image, however the blue chanel is very different from the UV image! Usualy the blue chanel is somewhat similar to the UV image, but not in this case. Here the green chanel is the most similar to the UV image.

So, apparently salmon flesh absorbs blue light very well but not UV light. Or I am doing something wrong?

 

Red

 

Green

 

Blue

 

UV

[Andy Perrin]

Oh, I have seen the blue be very different from the UV before. If you look at bananas, the skin is very dark in the blue but bright in UV.

[Andrea B.]

The salmon steak is interesting in the multispectral views. Apparently the marbling is some kind of animal fat which appears to be reflective in all wavelengths? We should try to look this up. Do lipids reflect IR, UV etc.

 

Any UV-reflective visible yellow/yellow-orange flower will have a similar response like the salmon.

 

 

^{Edit: I removed an incorrect remark I made about another flower! Sorry about that.}

[Jim Lloyd]

I guess if the visible blue was always similar to UV one wouldn't need to use modified cameras and filters. I think I might try to see how close I can make a visible image look like a UV one in my recent woodland shots (just out of curiosity).

I know that Lightroom has an IR filter which makes visible images look a bit like IR monochrome ones.I guess you could do the same with UV? Does anyone try subtracting a visible blue image from UV to highlight he differences?

[Andrea B.]

Between us all we have pretty much tried all the usual PS trickery - difference stacks, screening, channel stacks, overlays, and so forth. But that should not stop you by any means!!! It's important to play with this stuff and figure out interesting techniques.

 

Try putting the UV photo as a Luminosity layer over the Visible photo. That is also interesting for IR. I don't think I've seen woodland scenes layered like that. Wonder what it would look like?

 

Just try everything and see where it leads.

 

Question: I'm not sure of the vocabulary when you say "subtract" a visible blue image from a UV one? Which layer or tool is that? (We all use different apps & tools, it seems.) Thank you!

[Guest]

I'm suddenly craving sushi. What would pair well with fluorescent salmon?

[Andy Perrin]

Andrea, Difference in Photoshop is pretty much exactly what it sounds like: corresponding red, green, and blue channels are subtracted from each other. I’m not sure how it handles negative values.

[Hornblende]

Oh, I have seen the blue be very different from the UV before. If you look at bananas, the skin is very dark in the blue but bright in UV.

 

I guess if the visible blue was always similar to UV one wouldn't need to use modified cameras and filters.

 

You are right, I don't know why I remember noticing that the blue chanel is often similar to the UV image, I must have dreamt or something.

 

What would pair well with fluorescent salmon?

 

Avocado!