Image Size / File Quality Options

The D100 offers a wide variety of image size / quality combinations. At the full six megapixel resolution (3008 x 2000 pixel image size) you can choose from lossless storage options of RAW uncompressed, RAW compressed (run length compression) or TIFF-RGB. In addition you can also select from three different levels of JPEG compression at any of the selectable resolutions of 3008 x 2000, 2240 x 1488 or 1504 x 1000.

Standard Test Scene

To give an impression of what some of the combinations of image size and quality produce the table below is a cross reference of some of them:

• 3008 x 2000 RAW (uncompressed)
• 3008 x 2000 TIFF-RGB
  
• 3008 x 2000 JPEG Fine
• 3008 x 2000 JPEG Normal
• 3008 x 2000 JPEG Basic
• 2240 x 1488 JPEG Fine
• 1504 x 1000 JPEG Fine

Crops below are of the same 240 x 120 area of each image nearest neighbour magnified 200%.

Settings: Sharpening: Normal, Tone: Normal, Color mode: I (sRGB), ISO 200, 50 mm F1.4 D @ F8.0

	3008 x 2000
RAW	9702 KB (Nikon RAW uncompressed .NEF)
TIFF	17,711 KB (not available for download)
JPEG FINE	2,705 KB
JPEG NORM	1,402 KB
JPEG BASIC	736 KB
	2240 x 1488
JPEG FINE	1,529 KB
	1504 x 1000
JPEG FINE	763 KB

There is a noticeable difference in sharpness between JPEG Fine and RAW, the PC based RAW conversion software has much more processing power available and does appear to apply slightly more sharpening to the image before output (default settings were used to convert the RAW image). Getting back to in-camera formats the JPEG Normal setting doesn't seem to introduce too much in the way of visible artifacts and would seem to be more than acceptable for everyday shooting, especially if you have a limited capacity storage card. Smaller output size images are of course very sharp and detailed, reducing 6 million pixels down to 3.3 (2240 x 1488) does produce a very sharp and smooth image.

Image settings: Color Mode (Color space)

The D100 provides three color modes, Mode I and III are both mapped to the sRGB color space and so images shot in these modes will look correct immediately and can be used as is. Mode III has been designed for use for nature and landscape shots, it provides richer greens and a more natural balance of other colours.

Mode II is mapped to the Adobe RGB color space, this provides for a wider color gamut but will more than likely require additional processing if you are shooting for an sRGB output. Many professional photographers and publications have standardized on Adobe RGB and so the fact that the D100 supports this color space natively is a big plus for the camera.

Still no JPEG colour space embedded profiles

One major disappointment was that just like the D1H & D1x the D100 does not tag its JPEG images with the color space selected, this means that if you drag and drop an Adobe RGB (Mode II) image into Photoshop it will assume it is sRGB. Indeed, worst than that the most recent Photoshop (7.0) will see a D100 Adobe RGB image with an sRGB profile and tell you the image is sRGB (even though it isn't). The only way to distinguish an sRGB from an Adobe RGB image is to use Nikon View and manually rename or separate images.

Color space: some background

Below is a chromaticity diagram (CIE gamut), the main colored area represents approximately the range of color which the human eye can resolve. Inside this you can see three triangles, the two we're interested in are Adobe RGB (1998) and sRGB.

sRGB was a standard developed primarily by HP and Microsoft, it's the most common (and default) color space for PC (and Mac) computer monitors and is the color space assumed by many applications (including web browsers). sRGB has a limited gamut (range of colors) but would be the common choice for those shooting for the web.

Adobe RGB (1998), defined by Adobe Corp. is the most common colorspace used by professional graphics designers, publications and digital imaging professionals, it provides a much wider gamut (range of colors), it has a much better ability to capture very deep or bright color. HOWEVER unless your photo application knows the image has been recorded in the Adobe RGB colorspace it will look 'dull' on an sRGB device and will contain incorrect color casts in certain colors (such as greens looking too yellow, etc).

Color modes: I, II & III

Here's how the D100's manual describes each color mode:

• I - (sRGB) - Choose for portrait shots that will be printed or used “as is,” with no further modification. Photographs are adapted to the sRGB color space.
   
• II - (Adobe RGB) - Photographs taken at this setting are adapted to the Adobe RGB color space. This color space is capable of expressing a wider gamut of colors than sRGB, making it the preferred choice for studio photography or images that will be modified as part of a commercial production work flow.
   
• III - (sRGB) - Choose for nature or landscape shots that will be printed or used “as is,” with no further modification. Photographs are adapted to the sRGB color space.

We shot the same scene in each color mode. On your monitor the sRGB images will have colors that look more saturated, vivid and accurate. The Adobe RGB image will look dull (because your browser treats it as being in the sRGB colorspace). If you download the Adobe RGB JPEG, load it into an application that supports color profiles (such as Adobe Photoshop) and then 'Assign Profile' -> 'Adobe RGB (1998)' you'll see colors accurately.

Settings: Sharpening: Normal, Tone: Normal, ISO 200, 24 - 85 mm G @ F8.0, Small/Fine JPEG

Color mode: I	Color mode: II	Color mode: III

sRGB Mode I vs. Mode III

The difference between mode I (sRGB normal) and mode III (sRGB landscape) are subtle but noticeable. Below you can see a direct comparison of one row from the Gretag charts for each mode. In mode III blues and greens are stronger (with a slightly different hue) and reds are toned down very slightly.

Outdoor scene example

As you can see in the sample below the difference between color mode I and III can be more clearly seen in the green of natural foliage.

Color mode: I	Color mode: III