Image Size / File Quality Options

The EOS-1D has four default image size / quality options. In RAW mode (lossless compression) the camera records all 2496 x 1662 effective pixels, although only the standard 2464 x 1648 images can be output by the Canon TWAIN utility. In JPEG mode there are two compression levels at the Large size (2464 x 1648) and one at the Small size (1232 x 824).

Both Large/Fine and Large/Normal can have their JPEG compression level reprogrammed in a parameter set (up to three of which can be available on the camera at any one time). This allows you to define the level of JPEG compression and thus amount of space which will be occupied by each image on the CF card. For example it could be useful to have a parameter set which set the Large/Fine JPEG compression to the best possible quality (10) for shooting virtually lossless JPEG.

To give an impression of what some of the combinations of image size and quality produce (including some of the non-standard parameter driven JPEG compressions) the table below is a cross reference of the images available below:

• 2464 x 1648 RAW (saved from Canon TWAIN 4.0)
• 2464 x 1648 JPEG Large/Fine (quality 10)
• 2464 x 1648 JPEG Large/Fine (quality 8 - default)
• 2464 x 1648 JPEG Large/Fine (quality 6)
• 2464 x 1648 JPEG Large/Normal (quality 3)
• 1232 x 824 JPEG Small/Fine

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

Settings: ISO 400 / Color matrix: 1 (sRGB)

	2464 x 1648
RAW	4,138 KB (Canon RAW file - despite the TIF extension!)
JPEG Large /Fine (10)	2,400 KB
JPEG Large /Fine (8)	1,864 KB
JPEG Large /Fine (6)	1,124 KB
JPEG Large /Norm (3)	798 KB
JPEG Small /Fine	455 KB

As you can see both JPEG quality 8 and 10 are difficult to distinguish from RAW, as we get down to quality 6 we can see some JPEG artifacts creeping in to the boundary between details and flat areas. Having said that it would be perfectly acceptable to use quality 6 for general shooting and moderate size prints. Overall I'm very happy to see Canon add such a large degree of flexibility to an important and often overlooked aspect of digital photography (JPEG files). Kudos.

Tone curve

Unique to the EOS-1D is the ability to create 'tone curves'. These curves have five control points and define how the linear image captured by the cameras CCD is translated into a gamma space which will make the image look natural on our displays and print media. Curves can be defined in the TWAIN software, each curve has five control points and can be defined across the RGB colour channels or for each channel independently. A curve can then be loaded into a Parameter set (up to three sets can be stored in the camera at any one time, in addition to the standard set).

This gives the photographer the ability to shoot subtly different tonal balances for different situations. For example it may be useful to produce a tone curve used for shooting products under studio lighting and another for shooting a sporting event under stadium lighting. Or it could simply be used to produce a standard 'look' the photographer requires.

Settings: ISO 400 / Color matrix: 1 (sRGB)

EOS-1D Standard Tone Curve	Modified Tone Curve 'lighter'