Today I will talk about what could be essentially considered an alternative to using HDR (which will also be an alternative to using exposure blending) using layers in Adobe Photoshop, as well as image averaging, to essentially increase the dynamic range of your camera. First of all, I would like to mention a common problem with modern cameras: dynamic range. The general rule is that the more expensive a camera is, or the larger a camera's sensor is, the larger the dynamic range is. Currently, the average dynamic range of modern SLR cameras is about 12 stops of exposure or so, while the dynamic range of the human eye is supposedly about 14 stops. I won't be going into what these numbers mean in this article, but what this article is about is basically how to improve photos that were taken in lighting that produces a significant amount of contrast, which can cause detail, or information, to be lost in the shadows and/or highlights (bright, overblown areas of image). I didn't learn this technique from reading or hearing about it; instead, I learned it myself thanks to my experience with Photoshop.
Here is a side note: It is supposedly better to underexpose an image rather than overexpose it, since an underexposed image is supposedly easier to enhance (easier to bring back shadow detail than to bring back highlight detail) as modern digital cameras can't handle slight overexposures too well. So, what I do before I use any of these techniques, I slightly underexpose the photo while capturing the photo.
When I was stacking, or combining (otherwise known as overlaying) photos in Photoshop which were virtually identical (same lighting, same photos captured at a different time) and playing around with adjusting the layer blending modes, I was quietly, but fairly, surprised by the fact that I can use the blending mode known as "subtract" to decrease exposure and the blending mode known as "add" to increase exposure. This is not so important when you're capturing a photo using RAW format, as you can adjust the "exposure" slider in post processing. However, sometimes even capturing a photo by using RAW format doesn't guarantee that you can achieve a perfectly exposed image with detail in both shadows and highlights. Be careful with the subtract and add blending modes, and the resulting effect might be overwhelming or too much for your needs. However, you can adjust the opacity of a layer, so you do have at least some flexibility although from my experience, I have discovered that mixing layers this way can lead to the creation of "fake" detail which doesn't appear as pleasing as if you would have otherwise used HDR or exposure blending.
Now, as I have mentioned I will also talk about image averaging. Sometimes, when you increase the brightness of shadows to bring out detail, whether this involves HDR, exposure blending, or simply adjusting the exposure (or even shadows) slider, you might realize that the areas of the image that were full of darkness before are now grainy, or in other words, have lots of noise in them. This is where the technique known as image averaging can become helpful. This technique is the second best thing to magic, in my opinion. Image averaging is a method that implies stacking, or overlaying, images so that you can end up with an image that has no more noise. So, if you're trying to capture an image and notice that the shadows are significantly darker than the midtones and you think that the camera might not be able to catch as much information in those areas, then you might want to employ this technique. The number of photos that you take depends on how dark the shadows are, or how much noise is visible in the images (how high the ISO value is). Just take multiple images of the same scene without letting the camera move, so using the same lighting and perspective, and then load them into Photoshop (or any other program that uses layers). Next, you'll want the opacity to be different for each layer so that the bottom layer is set to 100% opacity, while the next layer up is at 50% opacity, followed by 33% opacity, 25% opacity (going bottom to topmost layer), etc. Or, after loading all of the images as layers, you could go to
You should be able to figure out the formula based on these opacities. However, do you really need to go through this much trouble? The answer,if you're lazy like me, is no. GIMP employs it's own script that you can download for free that takes the manual process and automates it with the use of the average layer plugin. Or, if you're using Photoshop, then follow this tutorial: https://www.youtube.com/watch?v=4SDgfB9I4As. There. Now you have learned an alternative technique that can be used to restore shadow detail without affecting image quality.
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