Instructor Brooks Dierdorff Tyler Yokoyama
February 4th, 2011 ARTO 354
Chapter Summaries
Chapter 2: How Camera Raw Works
Chapter two was kind of review for me, but it was nice to confirm many things I haven’t heard for years. It describes characteristics and functionality of a RAW image section by section. First we have Pixels and Resolution which deals with when the sensor picks up light, it produces a pixel and how the quality of an image can greatly depend on ppi (pixels per inch). Bit Depth was a new term for me, but an amazing feature of RAW images. With JPEGs having an 8-bit depth, they only contain 256 (2^8) shades of each color value. A RAW image has the capabilities of recording in 16-bit depth, 65,536 (2^16) shades of each color value. This means that if you have the same scale from black to white in JPEG and RAW, in each step of the jpeg, there are 256 steps in between on the RAW version. Technically, Photoshop only uses 32,769 levels which is one level more than 15-bit color, but they have their reasons that I do not understand.
Another important thing to remember with Photoshop is image degradation. When an image’s pixels are changes multiple times, depending on your edits, they can start to bunch up becoming similar values to pixels around them. They will also deter from their original and not look true. That is why you must use Camera Raw & Lightroom which do not alter the image’s pixels at all. Lightroom may cause a little image degradation, but not as bad as Photoshop. Camera Raw and Lightroom alter changes to a layer above the pixels. The original data is left untouched, but the lighting, contrast, and many other things can be changes without losing any quality.
Chapter 4: Camera Raw Controls
This chapter is really detailed in describing how to make certain changes and the many ways to approach it. It shows how to specifically use all of Camera Raw’s tools, fix distortion, hide chromatic aberration, and vignetting, among many, many other problems. The nice thing is that they will show you an image, zoom way in so you can see the problem, then show multiple subsequent images as they make alterations to come up with the best finished product. This book goes over 100+ images and how to fix them using more manual means, and using Camera Raw / Photoshop’s automated process, such as fixing chromatic aberration. You can use the slider bars to personally fix the Red/Cyan Fringe and Blue/Yellow Fringe, or select the “Highlight edges” or all edges” under “Defringe” to automatically take care of the problem.
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