[PDF] Treasure Island by Robert Louis Stevenson in Arts-Photography

Review

1 of 1 people found the following review helpful. Fantastic BookBy K. MarshallBy far the most comprehensive book covering HDR topics. In my opinion the authors of this book represent a dream team in HDR expertise! I believe this book is a must if you are interested developing HDR applications.17 of 17 people found the following review helpful. 5 orders of magnitude input to 2 orders of magnitude outputBy W BoudvilleFrom the other reviews about this book that came about via s Vine program; you might infer a possible problem when the book is a deeply technical exposition. Frankly; it was over the heads of several reviewers; several of whom admitted as much. So lets see what I can contribute.The subject of High Dynamic Range imaging exists mostly because of a simple observation. When you look with your eyes at a natural scene; typically outdoors in daytime; the dynamic range of the image can vary up to 5 orders of magnitude in intensity. But when the scene is captured and then displayed; the output page or screen can often only show 2 orders of magnitude. The latter is called Low Dynamic Range imaging. The conventional 24 bit RGB representation; which allocates 8 bits each to red; green and blue; is for LDR. The 8 bits in each colour channel is that 2 orders of magnitude variation.The book also explains clearly why 24 bit RGB is really effectively 8 bits or 2 orders of magnitude range. You might think naively that we have 24 bits of variation. But the text takes an example image; of an outdoors scene; and does scatterplots of red; green and blue pixel intensities against each other. They are strongly correlated. Which makes sense; when you realise that a pixel that is bright in red is often also bright in green and blue. The practical effect is that the information content in 24 bit pixels is actually much less than 24 bits. Which also explains why a mapping from RGB to other colour spaces that use 1 luminance channel and 2 chromatic channels is often performed. The latter 2 channels have much less information and so can be better compressed.Anyhow; the top level understanding of this book is to appreciate the discrepancy between the 5 orders of magnitude in an actual scene and the 2 orders in an output image. This impedance mismatch accounts for most of the books complexity and length. Many of the algorithms strive to somehow capture more of the natural dynamic range and make it visible in the far more restrictive output.The book seems ideal for a colour scientist or engineer who wants a deep understanding of the optical interactions as well as the physiology of human image perception. It is not meant for someone who needs a quickie tweak of an existing software imaging package. Rather; the book helps explain the science behind those packages; which might be often way more intricate than can be appreciated by the typical users of such packages.You can see this for yourself by reading many of the other reviews. Most are cursory and utter drivel. Written by people who were clearly out of their depths in terms of understanding maths or science or engineering in the text. Several reviews were just a short paragraph of generalities. Written by people who got their books thru the Vine program and just needed to post a review to satisfy the Vine requirements. Basically so that they could continue to get more free books from Vine.0 of 0 people found the following review helpful. The science behind what you seeBy Personnei first learned about HDR (High Dynamic Range) photography several years ago; when I was still shooting with an inexpensive point-and-shoot camera. Although the basic exposure was correct; the shadows were black and devoid of detail and the highlights were blown. Even now; shooting with a high-end DSLR I can still find myself in challenging situations. No matter the quality of the camera; it still cant capture all that the eye can see. By making several exposures and combining them; its possible to capture more of the dynamic range of a scene. The stunning (and occasionally cartoonish) results are easily found in a number of photographers catalogs.But thats just the beginning. The six authors of this book--essentially a college textbook on digital imaging--have collected information that covers the gamut of high dynamic range. The core is the human optical system. Our eyes and brains have remarkable capabilities as well as weaknesses. We are highly perceptive and also easily fooled. It is critical to know how this system works so that we have the best solutions to imaging problems. This is discussed in depth at several points in the book. I particularly enjoyed learning about the wonderfully-named "Cornsweet Effect"; which is the basis of sharpening filters in image-processing programs. There is a nice early example from the work of painter George Seurat.The book covers computer displays; film; televisions and printers--any technology that puts images in front of our eyes. Even when an image is captured with high range; it must have that range reduced to fit on such devices. How do we manage the data for the most satisfying transformation? In the near future; we may have to go the other way. We have millions of LDR (low dynamic range) images that must be displayed on new generations of displays. How do we transform these images in a convincing way?If youre a photographer looking for practical tips; this is not the book for you. Its a science book with plenty of math (including calculus). It represents a core of knowledge thats clearly required for developers of animation and photo-editing programs. Even if you skip the math; theres plenty of interesting information that may be of value to the more scientifically-minded photographer. If youre a scientist or engineer in the imaging field; its required reading.