There is a tiny bit of clipping in the RAW data, but doing a non-linear RAW conversion results in most of the rapids being clipped to pure white. The image in the example below is backlit by the sun, making the white rapids want to wash out to white and lose detail. What follows is the solution that I devised to this problem. At this point, the next logical step seemed to be to devise a way to blend these techniques to combine their advantages and eliminate their drawbacks. Linearly converted RAWs always resulted in the best B&W images with the most highlight and shadow details, but non-linearly converted RAWs nearly always had the best color. But getting good color out of a linearly-converted RAW can be an even more frustrating experience.Īfter experimenting with linear and non-linear conversion for a while, I concluded that each method had its own strengths and weaknesses. Keeping detail in the dress and the tuxedo from being clipped can be an extremely frustrating experience. This can pose a serious problem when photographing subjects with an inherently wide dynamic range, such as a bride and groom wearing the typical white dress and black tuxedo. In many cases, the output will be clipped to white or black before the actual RAW data is clipped. Most non-linear RAW converters have difficulty dealing with extremely bright highlights and deep shadows. The greatest advantage of linear RAW conversion is that it allows the use of the entire dynamic range of the sensor. I discovered that if I normalized the color channels of a linear RAW conversion (basically "stretching" the values of each color channel so that they ranged from the minimum to the maximum values) and then applied a gamma adjustment of about 4 to 5, I would have a color image that, while frequently looking a bit odd in color, would always convert to a very nice B&W. But the slightly odd-looking color common to linearly converted RAW images is not an issue when the image is being converted to B&W. In addition, images converted in linear mode tend to be extremely dark, and require fairly radical gamma adjustment to get the image to look "right".
Linear RAW conversion is difficult to use for color images because no tone curves are applied to the image data there is no profiling or color adjustment done during the conversion process.
As I refined my B&W technique, I began using linear RAW conversion because it allows one to easily make use of 100% of the dynamic range captured by the sensor. I love the creative flexibility of adjusting the mixture of the various color channels to create a really striking B&W image. I have nothing against color in images, but I have a deep appreciation for really well-done B&W work. I’ve always been a little bit schizophrenic in my approach to color in photography.
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