HDR Arising
The HDR has come out for several years, yet it has been more popularized lately accompanied by a large amount of new software.
I will present HDR effect and make clear why we ought to use HDR.
Firstly, in order to make my word more understandable, I will explain some relevant technique terms: DR, HDR. First, DR, Dynamic range (DR) stands for the range of luminance values from the darkest to the brightest. Second, HDR, High dynamic limit (HDR) in photography means representing the full range of tonality present in the scene with high percentage faithfulness.
In aspect of photography, HDR makes an unprecedented difference. For example, we want to clip a view of landscape at sunrise, which is time for go out. We see clouds, sky and remote trees. What our eyes can see are flaming sky, colorful clouds and blocks of trees, which are very picturesque. However, the picture we get with camera shows us that the clouds are lacking drama, specific and color, parts of sky are over exposed and distant trees turned to be muddy blur. How does it occur? Actually, it is caused by the DR I mentioned previously. The luminance values ratio of the world is 100,000:1, and that of what our eyes can perceive is around 10,000:1, only one in tenof the former. And camera even can capture landscapes of 400:1. This is the reason that makes our pictures not true to the original world.
It is time for us to use HDR. What effect after all can HDR get? You must be thirst to know this. HDR techniques can be made use of for processing either singles or stitched panoramic photos. In such situation I refered to before, processing stitched panoramic images is needed. I am going to present you the general procedures of making HDR images, but not detailed technical ones. We must take at least three pictures of a same view with different bracketed exposures. The landscapes of the three or more must be of no distinction. It also requires that we cannot move the position of camera catching these images. Then a fixed tripod is helpful. If you want to make a perfect HDR image, you may as well choose the scenes without any moving things or people, no change of light, and any wind, as good as taking static things, otherwise there will be ghosting in your image. Draw the dark segment of the over exposed image and the bright segment of the under exposed ones, and combine them together. In a word, take the best portion of each image and combine them together to make a perfect photo . The landscape is identical with the original, and the HDR photo will be more lifelike and vivid than the unmodified one.
The example I presented above is just to show you part functions and effect of HDR techniques, which doesn't mean that HDR technologies is the exclusive right of the professional picture takers.
With my presentation, you just get a little information about HDR. The next thing we should do is to taste and practice it in person.