26 Opening NEF files with Color Managed and Non-Color Managed Programs.

 

The D-1 X and H can produce files in one of two Color Modes.

Which Color Mode Should I Choose? The choice of Color Mode depends on the job requirements. It is important to note, however that in general image browsing applications such as Fotostation, ACDSee and web browsers use sRGB color space. If files have been created in Adobe 1998 Color Mode, then they will display in these programs with flatter tones than are actually in the file. To open an Adobe 1998 file in an sRGB editor will force incorrect Color choices to be imposed on the file data, a fundamentally wrong decision.  The versatility of the D-1x/h cameras means that the Color Mode of the can be changed post-shoot in Nikon Capture. Therefore the decision as to which color mode to use at the time of shooting can be based on simple convenience to ensure authenticity in the browsing/editing environment. Certainly for rapid image editing, by selecting sRGB (Mode 1) the files will be viewed with authentic color in browsing programs and can be converted later for further editing if required.

If the same scene is shot in in two Color Modes and each image is then viewed in its' correct Color Space, then the overall appearance of the hue and saturation of the two image will be similar, although the range of tones in the picture will be different.

	Fig 1. Shot in Mode I (sRGB)
	Fig 2. Shot in Mode II (Adobe 1998) and converted to sRGB in Adobe Photoshop.

This is a basic rule of Color Management: the same image shot in different color spaces will, in general look similar if viewed in the correct Color Space or if converted into the same Color Space.

However, if the two files are viewed in the same Color Space, the appearance - most notably the saturation - will appear very different. This mistake usually gives rise to a false impression of the color characteristics of one or other Color Space: sRGB in an Adobe 1998 environment looks over-saturated, and Adobe 1998 in an  sRGB environment looks flat.

	Fig 3. Shot in sRGB, viewed in sRGB.
	Fig 4 Shot in Adobe 1998, no conversion, viewed in sRGB (incorrect workflow - image looks flat due to viewing in wrong color Space)

As any application (for example the browser in which you are viewing this image) only supports one color environment at a time, viewing two images that were created with different Color Modes will result in one being displayed incorrectly appearing either flat or oversaturated.

This is another important rule of Color Management.

The TFT monitor of the camera is a good example where this phenomenon can be observed: two images of the same subject taken in different Color Modes will appear different in the TFT monitor, but if viewed in their correct Color Space on a computer will look similar.
There is a strong possibility that the color characteristics of an image will be misjudged if these principles are not understood.

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Work Flow

A further opportunity for mis-judgement occurs when a NEF file is converted into an RGB format by the file library, Photoshop plugin and Nikon Capture.

In fact there are three routes by which a file may be produced, and unless clearly understood, the results can be misleading.

Case 1: Nikon View  (or other Non-Color Managed Application)

Nikon View is an non-color managed environment. When a NEF file is opened (converted to RGB and saved) the Color Mode setting is read from the file and Nikon View produces a file with the characteristics of the designated Color Mode, as set in the camera. It is important to understand that the image data in the NEF file data does not itself have a Color Mode or Color Space: the Color Mode is supplementary information (a data tag in the file) which is then used by Nikon View to process the file into the appropriate color space.

The result of saving two NEF files with different color characteristics into RGB mode using Nikon View will be that each will look different if viewed in the same Color Space (See Fig 3 and Fig 4) , and similar if viewed in the correct Color Spaces (or converted (Fig 1 and Fig 2).

This behaviour is repeated in the case of other non-color managed environments such as Fotostation 4.5 and Photoshop 4.0 LE.

Tip: When using these applications is it important for the user to add information, for example, in the file name or IPTC text to identify the correct Color Space for the file as there is no possibility to embed an IPTC tag in a non-color managed application.

In effect, Nikon View or any other non-color managed application is acting in the same manner as the camera body itself. The output file is processed into the Color Space set by the Color Mode of the camera at the time when the picture was taken.

Case 2: Photoshop 6 (or other Color Managed Application)

When opening the file in a Color Managed application such as Photoshop 6.0, the Color Mode of the NEF file is read and passed to the application. If the Color Mode of the file does not match the application's Color Space,  the application will respond according to the color setting preferences, for example automatically converting the file or signalling that there is a  Color Space discrepancy.

Following the above working example of two identical pictures taken in the two different Color Modes, the file from the other Color Space, when converted, should resemble the file in the correct color set in Photoshop. (see Fig 1 and Fig 2) In this case the Nikon Photoshop plugin is acting consistently with expected  behaviour of a Color Managed environment, passing the file to the application with a Color Space tag.   

In effect, the  Plugin is acting like the camera body, but producing a tagged RGB file, which is then checked by the application before it appears in the Photoshop window.

Case 3: Nikon Capture

In the case of Nikon Capture, the NEF file is always opened into the application's Color Space and the Color Space information in the NEF file is ignored. Nikon Capture therefore treats the NEF file in a completely neutral manner and just processes the raw data according to the Color Space defined within Nikon Capture. .

Two NEF files taken with different  Color Space settings will open with identical color appearance regardless of the Color Mode set in the camera.

Nikon Capture allows the Color Space of the image to be set from a number of alternatives after shooting, regardless of the setting in the camera. This feature allows greater versatility in workflow as the Color Space is determined after shooting.

 

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Summary

File Library or Plugin into non-color managed application: file is created with the characteristics of the chosen Color Mode, as if it were being processed by the camera body. 

File Library or Plugin into color managed application: file is created with the characteristics of the chosen Color Mode and then flagged to the application if different.

Nikon Capture: Color Mode in the NEF file is ignored. File Color Space is set by Nikon Capture CMS setting.

 Tabular Summary

Application	Environment	Color Space Definition	Color Space Identification
Nikon View, Photoshop 4, Fotostation	Not Color Managed	Color Space set by Camera Color Mode	Add manual Color Space identification (e.g. in filename) and convert manually.
Photoshop 6	Color Managed	Color Space set by Camera Color Mode	Photoshop can be set to convert colors automatically on opening file, and to embed Color Space Tag.
Nikon Capture	Color Managed	Color Space set by Nikon Capture	Color Space tag embedded by Nikon Capture when file is saved.