Help with Color Space Adobe RGB

Started Aug 20, 2010 | Discussions thread
Brooks P
Veteran MemberPosts: 9,183
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Re: Help with Color Space Adobe RGB
In reply to DebraE, Aug 20, 2010

I don’t have PSE-6, I have PSE-8 but I’m fairly sure the color profiles work the same. For either file type (NEF or JPG) all you have to do is click on Image on the menu bar and then click on Convert Color Profile; you can remove the color profile entirely or you can convert the profile. If the file is sRGB you have the option to change to Adobe RGB and vice versa if the file is Adobe RPG; the conversion is instantaneous.

There are several sections to a raw (NEF) file; the actual raw data which is nothing more than the values recorded by the pixels, all 12,000,000 of them. Basically the pixels count photons, they measure the intensity of the light. There is a Bayer Layer sitting on top of the pixels that filters out light so that each individual pixel only measures light in one of the wave lengths (RGB). The program that converts this data to an image has to know what color each individual pixel is measuring, it has to know the how the Bayer Layer mosaic is laid out. Other sections of the file contain the Metadata, which includes such things as the exif data. There are two jpeg images in the NEF file as well, one small one for use as a file icon and a full size jpeg created by the camera. Many programs, including operating systems extract these imbedded jpeg images when they display a NEF file. Every model has its own unique NEF file, no two models use the same NEF file layout.

When you edit a NEF file, an image has to be generated from the raw data, and it is this image that is edited – the raw data is never altered. A log, a listing of the edits, is created and saved when you edit the file. ViewNX and Capture NX2 store this edit log in a section of the NEF file; Adobe uses what is called a Sidecar file, a new file with a “.xmp” extension, to keep track of the edits. Each time the NEF file is opened a new image is created and the edit log is read and the edits applied so you see an image that looks just like the image you edited. Because the raw file is never changed some people refer to it as a digital negative; that isn’t quite right but it helps some people understand the principle that the original data always remains the same – it is easy to go back to the original image.

Because different photo editing application manipulate the data differently and maintain the edit log differently, edits made by one application can’t be viewed by another application. Change a NEF file with PSE-6 and you won’t see the changes when you open the file with ViewNX, and vice versa. You can have two totally different looking images, one created by Nikon software and one created by Adobe (or any other third-party software), but the raw data remains unchanged. The ramification of this is that sometime in the future when you have a new application or your post processing (PP) skills have improved you can go back and create a new and very possibly better image from that NEF file.

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While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

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