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JPEG / RAW Image Size & Quality


Standard Test Scene

The Kodak DCS-14n provides two different image format options, RAW and JPEG. A RAW image can be seen as a 'digital negative', the pure image data directly from the sensor, unprocessed and unadjusted. This RAW image must be processed / viewed using the DCS Photo Desk software. As a slight twist to our traditional understanding of RAW Kodak also provide reduced resolution options for RAW at 13.5 (full), 6.0 and 3.4 megapixels. Kodak RAW images have a '.DCR' file extension and are losslessly compressed (similar to Zip compression). A full resolution RAW image from the DCS-14n weighs in at around 13 MB.

The DCS-14n's JPEG format is also slightly different than other digital SLR's in that as well as the standard JPEG format you can also record in Kodak's 'ERI-JPEG' (Extended Range Imaging). ERI-JPEG images have the same '.JPG' extension and are completely compatible with the standard format. However, when opened using Kodak's FFM (File Format Module) for Adobe Photoshop they can be adjusted for color balance, color compensation and exposure compensation. ERI-JPEG images can contain up to two stops more exposure latitude than would be otherwise available. Examples of ERI-JPEG and the FFM in action can be found in the Software section of this review.

JPEG format images can be taken in 13.5 (full), 6.0, 3.4 and 0.8 megapixel sizes in combination with three different compression levels.

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. Note that the JPEG files are ERI-JPEG format.

  • 4500 x 3000
  • 4500 x 3000
  • 4500 x 3000
  • 4500 x 3000
  • 3000 x 2000
  • 2250 x 1500
  • 1125 x 750
(13.5 mp)
(13.5 mp)
(13.5 mp)
(13.5 mp)
(6.0 mp)
(3.4 mp)
(0.8 mp)
RAW
JPEG Quality III
JPEG Quality II
JPEG Quality I
JPEG Quality III
JPEG Quality III
JPEG Quality III
Images below are cropped 240 x 120 area of the image magnified 200% (nearest neighbour).

Settings:
ISO 80, Nikkor 28-70 mm F2.8D, Normal NR, Low SHP, Product Look
 

 
4500 x 3000
RAW
14,160 KB - not available for download, as a 2,614 KB JPEG
JPEG
III

3,648 KB
JPEG
II

2,966 KB
JPEG
I

2,572 KB
 

 
3000 x 2000
JPEG
III

2,103 KB
 

 
2250 x 1500
JPEG
III

1,305 KB
 

 
1125 x 750
JPEG
III

596 KB

At full resolution the JPEG III option delivers very clean images with no visible JPEG artifacts, quality II also appears to be quite good, there are some subtle artifacts but nothing to concern most photographers. Quality I is obviously a compromise between size and quality with some artifacts around areas of detail. The 14n also appears to use a quality interpolation algorithm for downsampling, lower resolution images are clean and smooth with good aliasing and no jagged edges. Indeed the six and three megapixel options deliver almost 'Foveon X3'-like crispness and detail.

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