# The Illusion of Color



## ceg4048 (24 Feb 2008)

In one of my favorite movies, The Matrix, the protagonist "Neo" is plugged into a neural network and his mind is transported for the first time into a computer program. He then asks his mentor "Morpheus" whether what they were experiencing is real. Morpheus' response is "What is _Real_? Real is merely electrical signals processed by your brain."

I always think about this movie whenever I try photographing my tank because I'm trying to convey in a photo what I think reality ought to be. Rarely does the resulting image agree completely with what's in my minds eye and if it ever does then it was a result of dumb luck more than anything.

This happens because the visual cortex and the human mind (whatever that is) processes light differently than a camera does. The result is that you have to subsequently manipulate the photo to construct an optical illusion that represents what you thought you saw in the first place.

Recording color in an aquarium fitted with weird lights is a major problem because the mind is able to do a much better job of filtering than any machine. I love color photography and the more brilliant the better, but hitting the "right" colors is always a struggle for me. If you check Dave Spencer's thread on White Balance: http://www.ukaps.org/forum/viewtopic.php?t=337 you'll see that any WB setting can produce an acceptable photo depending on what your favorite colors are or on what mood you are trying to accomplish in your minds eye.

Here are some photos taken with a Nikon D200 and various lenses. All the photos require manipulation with an image program such as Photoshop to even get close to what you thought you saw.

This shot is done with AWB - but the in camera solution was very green, which baffled me. This side of the tank is lit with one 8000K lamp, one 6500K lamp, one 5200K lamp and one 4200K (front to back). With such a kaleidescope of lamps it's no surprise the camera has difficulty but why a green cast? Although I could remove the green the green stems plants was too sterile. The red plants in this shot are as I recalled "seeing".




I decided to do a pre-set custom white balance by putting a white card in the tank under the lights and measuring the white . The resulting shot shows the stems as I remember (with much more yellow) but the gravel and red plants now look stained and less pleasant. This is the best correction I could muster.




I had to think hard about why this should be. What color are these plants "really"? The answer is that it always depends on what light is used to view them. With AWB the camera produces a green cast because regardless of the color of light supplied the plants, all reflect green, which adds a significant amount of green. Light entering the tank is diffused, reflected and scattered., and no matter what color the source starts out as it will be influenced by the color of the plants in the tank.

Although the custom AWB didn't deliver my minds rendition across the entire frame it did a better job of recovering subtle colors lost by AWB. A few examples:

Ammania shot using AWB is OK, the color is nice but uniform. The custom WB is a subtle but noticeable improvement.


 



AWB de-emphasizes the yellows/reds (cool). Custom give a more continuous tonal range, warm  (under these conditions).


 



Another problem with the light is that there is tremendous falloff of intensity as the distance from the bulbs increases. This makes it difficult to meter since the very bright parts of the image can get blown away. I decided to stick with Custom WB for shots above mid-line. With an SLR you can spot meter the very brightest area and take the penalty of underexposing the lower portions of the image. This is the only way to preserve bright textured surfaces.


 



What about flash? Sometimes it's the only solution if there is an extremely large difference between the brightest and darkest portion of the image and if you don't want to lose the shadow details. Flash has it's own problems but the WB equation is easier to solve, however, the "look" is totally different.

Here is a shot that only a Crime Scene Investigator could appreciate. The harsh lighting of a flash in this case obliterates the subtle tones, texture and translucency seen in the preceding shots. It's easy to see here that light penetrating from the surface would get filtered to yellow and green. Pitty the poor carpet plants.




In my tank I'm limited to frontal shots because the sides are covered This shot is with fill flash and is on the cool side but at least texture is preserved.




Since there is no "real" solution we should play with various color balances until we can approximate what we imagine. Use one WB setting for certain areas and other settings for other areas depending on what you are attempting to convey. Remember a good image program is critical to achieving this:

Macro shot of Didiplis diandra lassoed by a strand of algae (AWB).




Hatchet Bomber Squadron cruising over a green field. Custom WB.




Early afternoon sunlight shining through the front glass at Ludwigia var Cuba transitioning to submerged state. AWB.




Limnophilia aromatica grove but two stems refuse to transition to submersed even after 6 months (a riddle for another day). Custom WB.




Sometine an image is appealing just because of the creamy colors. Even though the Custom WB gave the red plant an orange color cast it seemed to blend naturally.




Cheers,


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## George Farmer (24 Feb 2008)

Superb in all aspects.  Thanks for sharing, Clive.


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## Azaezl (24 Feb 2008)

Wow    fantastic pics!


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## Ed Seeley (24 Feb 2008)

Once you throw colour blindness into the mix too you can see why I find this so frustrating!!!!!  In the side-by-side picutres, the corrected ones look 'worse' to me (darker and less clear), probably because I have no Red cones to see red light!  

Great write up though Clive, cheers for the technical stuff!


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## Maximumbob (24 Feb 2008)

Excellent write up clive.. I think i'll have to read it a few times to appreciate it.  Still getting to grips with my DSLR.


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## Dave Spencer (24 Feb 2008)

Good stuff, Clive.

I have always found on one of my tanks that my Nikon always works best in AWB. On my retired 24l with Arcadia Arc Pod lights, experimenting was the key.

I haven`t tried using custom WB, but it is always something I have wanted to try, but not had the time.

For me, the way ahead is using a light box with the flash fired from overhead. I have a crappy light box that I have made up from cardboard and tin foil, but I have only used it once on my 60cm. The box allows too much light to leak out from the sides, affecting the background. It should have come out white.

Of course, using the flash helps to freeze the fish as well, which is a bonus.







The amount of light you get bouncing around it is nicely diffused, with no burn out. I still have a lot of experimenting to do controlling the flash output, but haven`t got the time at the moment. I need to build my light box out of something more rigid.

My next problem will using flash on a 120cm tank. Two flashes or more may be the answer.  

P.S. Love the Hatchet squadron.

Regards, Dave.


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## ceg4048 (25 Feb 2008)

Hi,
    Glad you enjoy the pics. Dave, your right about using the flash. A light box definitely helps but the Kelvin temperature of the flash simulates the light of high noon, i.e a lot of blue. Depending on the angle of the shot you can lose some of the reds. The flash does allow you to use lower ISO and smaller apertures though, so you can get better depth of field and have more of the shot in focus. Here is an example of a flash shot which gives a a decent rendition, and produces a nice reflective surface of the petals but something is still "wrong" with the reds and yellows. They seem to go to lime green.




On the other hand, if I can solve the puzzle of existing light I can get prettier yellows and reds with a custom WB. With existing light I'm forced to use higher ISO, but I can't reproduce these tones with the flash. Again it depends on the subject and what you are trying to convey, and what compromises you're willing to live with.




Here is the same plant using AWB. Again, a completely different gamut of colors. The reds go to purple. Importantly though is that I maintained the translucency which for me is more important in these specific shots than getting "accurate" color.




Ed, at least you'll be aware that when you take a shot, that you need to add more red in post processing for others to see. Two thirds of the megapixels in a digital camera record only green so I can understand how changing them to red in the image manipulation program would make the image seem darker to you.

Maximbob, equally important is to come to grips with Photoshop. The two work hand in hand.

Cheers,


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