Low light can present a serious challenge for even the most seasoned photographers.
Low light can present a serious challenge for even the most seasoned photographers. Light is the most important part of how we perceive images and all photography involves capturing the light reflecting off of a physical object.
"RAW, RAW, RAW!…that’s the spirit!” I hear this all the time from a number of folks who shoot RAW with their cameras.
So let’s talk about image formats. And by "talk,” I really mean converse. I’d like to hear what you think. Note that I am at least vaguely aware I don’t know everything.
We’re pleased to begin providing articles on improving your Restoration/Throwback images. We’re also pleased to be working with Rachel LaCour-Niesen of www.SaveFamilyPhotos.com / #savefamilyphotos.
The below “conversation” begins this collaboration with a topic that is near and dear to all of our hearts – the connection to our past that photography provides. Both the images and the stories they suggest allow us to be a little closer to those no longer with us.
While we strive to make improving your pictures as easy as possible, sometimes people send comments to Support saying that the our software is not doing what we said it would do. On rare occasions, these requests would require the Magic of Merlin to retrieve anything worth looking at. But more often than not, when the customer sends an image, I can see that there is plenty to work with, and that our software can do a pretty good job of fixing the picture in less than a minute.
Remember Tina? She had a bad experience with a nationally known purveyor of printed pictures. Then she tried again at Vivid-Pix-Prints to get her pictures printed. Here is her reaction:
"I got my pictures back from vivid-pix today! Some of them look insanely better, much sharper, clearer and brighter, it's hard to believe that they are even the same picture. While others are still better, clearer and sharper it, was more subtle, but getting them through vivid-pix definitely makes a difference. I'll be printing my SCUBA pics through you guys from now on!
Thanks again for all the help! " - Tina
Like I mentioned in the previous blog, Tina has a future in advertising!...
"I've recently used the free trial software to enhance my SCUBA pics. They look AMAZING on the computer, but when I sent some off to be printed, I was highly disappointed with the results. The images look grainy or pixelated and the contrast looks terrible. My camera is an HD quality camera. I was wondering if you had any tips on how to get the pictures to look as amazing printed as they do on my screen.” - Tina
We at Vivid-Pix have heard this lament from time to time. It’s really a shame to spend the time and money to go to exotic locations, take pictures of the wonderful things, make them look great with Picture-Fix, and then get lousy prints. You deserve images that accurately represent what you saw, not what a misguided print service spits out.
This is so cool...
Pardon me for the dated use of “cool.” I don’t have a better way to express what I feel.
I live in upstate New York, USA. No, not skyscrapers and concrete...this is primarily farm country. Think apples and dairy cows. And I actually enjoy living on what many people would consider the frozen tundra. As my daughter says, “The cold does not seem to affect you the way it does most people.” Yes. This is one of the positive attributes of Swedish and German heritage.
Heritage aside, it is absolutely great that I receive images from all over the world. Since I am responsible for the support of our Vivid-Pix software programs, I often have the chance to receive imagery captured by people on dive expeditions all over the globe. I can’t tell you how great this is. Don’t stop....
Though certainly not the norm, occasionally some photos can come out grainy.
When an image is very dark, or very low contrast, the potential for graininess rises. In particular, when your camera is forced to boost the low light level that it captures, the image may become grainy. You may not realize this is happening because cameras generally make this boost automatically. And some cameras do this boosting much better than others.
In order to enhance the contrast so that we see the image in a more dynamic and pleasing way, we are essentially amplifying the differences between pixels. If the image contains a good amount of visual noise (unwanted small image artifacts), the noise is amplified along with the image and becomes more noticeable in the form of graininess. There are filtering techniques that can be applied to reduce this, and we use them, but they must be used sparingly lest the image become “cartoony” due to over-smoothing the image.
Also, when an image is sharpened, it tends to bring out the graininess. Sharpening amplifies the differences between pixels, and visual noise or grain is exactly that...differences between nearby pixels. We have chosen a sharpening technique that minimizes this effect by attempting to sharpen only the actual “edges” of the objects in the image, but the technique is not perfect. Also note that the effect shows differently with different image content. For example, you rarely see graininess in the sand, but a “clear” blue background makes it obvious. Grain is also reproduced differently in different size images, with small images like our side by side being more prone to the problem than larger image files....
So just what is lightness and contrast?
In an image, lightness (or brightness) is the overall light level. The picture of an eel in a coral crevasse at 30 feet is a good example of an image without much lightness, unless you illuminate it with a strobe. A dolphin just under the surface can be an example of an image with high lightness.
But wait a minute…that dolphin may be nicely illuminated by the rays of the sun entering the water just a few feet above, but the odds are that the picture you took is not very close. The light bouncing off the dolphin and into your camera is filtered and lessened by the water in between. So that dolphin image may not have much lightness, even though the mammal is nicely lit. A better example of high lightness is a coral fan close to the surface, motionless or nearly so, allowing you to get close so that your camera can soak up all that light.
Related, but slightly different, is contrast. A good way to imagine contrast is as the difference between the brightest and darkest portion of the image. For that coral, it’s the brightest part, probably near the top (hopefully not bleached) where the angle reflects the sun best toward you, and the darkest shadow, lower down where the sun does not hit at the moment you clicked the shutter button....
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....
Have you noticed that your underwater images aren’t always as sharp as what you are used to seeing topside? That’s probably because the water scatters the light bouncing off your subject.
If you don’t want to loose any sharpness due to light scattering, you’ll need to capture your photos in a vacuum. Probably not very practical, and doubtful that your subjects would like it in any case. In air or water, there will always be some redirection of photons by the molecules in between your camera and your subject. The effect is more noticeable in water than air, due to the greater density of the water. The Pros always say, “Get close,” and minimizing the light scattering is another reason to do so.
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....