Vivid-Pix Blog

All Things Vivid-Pix!

Lookin' Sharper

Lookin' Sharper

While there are many techniques for sharpening, some yield better results than others.  We have selected one with a counterintuitive name...Unsharp Masking.  Why?  Because it tends to accentuate the important parts to the image without increasing visual noise or graininess.

Unsharp Masking actually began as a clever technique to enhance the sharpness of printed images in the chemical/analog world.  Digital Unsharp Masking is uses a similar technique, and works something like this:

- It’s good to determine what should be sharpened, so edges are detected.  This is in effect “applying a mask” so that only those parts of the image that are significant enough to enhance are subject to sharpening.  In other words, those areas that may have small differences from pixels to pixels, like water in the background, are not subject to sharpening, while the intricacies the fish scales are sharpened.

- A threshold is applied.  If the change from one part of the image to another at an edge is small, the edge is not sharpened.  If the threshold is set high, only major transitions are sharpened.   In particular, if you are seeing graininess and pixellation, set the threshold higher.

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Expose For The Highlights

Expose For The Highlights

Hi Vivid-Pixers,

In many respects digital photography has a lot in common with analog photography, meaning the use of film. For example both digital and film cameras use f/stops, shutter speed and ISO to govern exposure. Another commonality is that at depth the use of strobe light is required to “paint in” colors back into foreground elements. If not for the use of strobe light those colors would be lost from the selective filtration of white light from the sun that occurs as sunlight passes through the water column.

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Why Are My Pictures So Blue Or Green?

Why Are My Pictures So Blue Or Green?

As Marshall McLuhan said, "The medium is the message."

While I'm not so sure he was talking about underwater photography, the principle is similar.  The medium in which a signal travels influences the information received.  This not only happens underwater, but topside is well.  The sky tends to be blue (where you dive...not here in Rochester, NY, where gray is the dominant color) because of the differing interaction between atmospheric molecules and wavelengths of light.  

Underwater, a similar effect occurs, and is more dramatic.  Sunlight entering the water from above becomes filtered by the water, and the reduction of red light is greater than that of blue and green.  So the deeper you go, the percentage of red in the available light becomes less and less.  Additionally, the distance between you and what you are looking at provides an additional filtration, removing even more of the red light.  

Actually, your camera (without flash) does a pretty good job of capturing the scene.  The blue/green cast you see in your pictures is a good representation of the available light that bounced off the subject and was captured by the sensor.  But your brain does a really nice job of automatically balancing those colors into a much more pleasing color balance.  "Eyes, this can't be right.  I'll fix it for you.  You're welcome, Brain."  It auto white balances for you, without any conscious involvement.  So what your camera records is not what you saw.

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