HDR

High Dynamic Range:

HDR is a technique used in imaging and photography to reproduce a greater dynamic range of luminosity than is possible with standard digital imaging or photographic techniques. The aim is to present the human eye with a similar range of luminance as that which, through the visual system, is familiar in everyday life. The human eye, through adaptation of the iris (and other methods) adjusts constantly to the broad dynamic changes ubiquitous in our environment. The brain continuously interprets this information so that most of us can see in a wide range of light conditions. Most cameras, on the other hand, cannot.

HDR images can represent a greater range of luminance levels than can be achieved using more 'traditional' methods, such as many real-world scenes containing very bright, direct sunlight to extreme shade, or very faint nebulae. This is often achieved by capturing and then combining several different narrower range exposures of the same subject matter. Non-HDR cameras take photographs with a limited exposure range, resulting in the loss of detail in highlights or shadows.

The two primary types of HDR images are computer renderings and images resulting from merging multiple low-dynamic-range (LDR) or standard-dynamic-range (SDR) photographs. HDR images can also be acquired using special image sensors, like an oversampled binary image sensor.

Due to the limitations of printing and display contrast, acquiring an HDR image is only half the story; one must also develop methods of displaying the results. The method of rendering an HDR image to a standard monitor or printing device is called tone mapping. This method reduces the overall contrast of an HDR image to facilitate display on devices or printouts with lower dynamic range, and can be applied to produce images with preserved or exaggerated local contrast for artistic effect.

High-dynamic-range photographs are generally achieved by capturing multiple standard exposure images, often using exposure bracketing, and then later, merging them (usually within a photo manipulation program) into a single HDR image. Digital images are often encoded in a camera's raw image format, because 8 bit JPEG encoding doesn't offer a great enough range of values to allow fine transitions (and regarding HDR, later introduces undesirable effects due to lossy compression).

Any camera that allows manual exposure control can make images for HDR work, although one equipped with auto exposure bracketing (AEB) is far better suited.

  

hdrguide.com                                  www.unframedworld.com

HDR images are more like a dream world vibrant colour image, I'm not very keen on the HDR technique with the landscapes and city scapes it reminds me of cartoon like images. But the portrait images in HDR look quite effective on the particular image below it really brings his eyes out the image its the first thing you are drawn to his piercing blue eyes. I found a short video on youtube which shows you how the image started off to the end result. (Although it doesn't tell you what to do or how he done it). His portrait looks like its done in a studio using controlled light. 

https://youtu.be/N53IaahYRIY  

I attempted to do the HDR technique myself on some portraits using natural and controlled lighting. We also decided to try adding movement into the images to see what outcomes it would bring. I did the technique manually by taking a correctly exposed image then going 2 stops up and 2 stops down  to take 2 underexposed and 2 over exposed images, so in total I had 5 images to put together in Photoshop to create the HDR. By doing it manually you have to make sure the subject doesn't move while your changing the stops up and down. In the Pentax camera a setting within the camera actually does this for you without having to take 5 separate images and putting them together in Photoshop.