Image Size / File Quality Options

The EOS-1Ds has four default image size / quality options. In RAW mode (lossless compression) the camera records all effective pixels, although only the standard 4064 x 2704 images can be output by the Canon File Viewer Utility. In JPEG mode there are two compression levels at the Large size (4064 x 2704) and one at the Small size (2032 x 1352).

Both Fine and Normal JPEG modes can have their compression level programmed through the camera's parameter setup menu (up to three parameter sets 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 (but huge files).

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 compression's) the table below is a cross reference of the images available below:

• 4064 x 2704 RAW (saved from Canon File Viewer Utility 1.1.0.19 as 8-bit TIFF)
• 4064 x 2704 JPEG Large/Fine (Quality 10 - less compression)
• 4064 x 2704 JPEG Large/Fine (Quality 8 - factory default)
• 4064 x 2704 JPEG Large/Fine (Quality 6 - more compression)
• 4064 x 2704 JPEG Large/Normal (Quality 3 - factory default)
• 2032 x 1352 JPEG Small/Fine (Quality 8 - factory default)

Crops below are of the same 240 x 100 area of each image nearest neighbour magnified 200%.

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

	4064 x 2704
RAW	10,348 KB Canon RAW file - not available for download
JPEG Large /Fine (Q 10)	5,875 KB
JPEG Large /Fine (Q 8)	4,369 KB
JPEG Large /Fine (Q 6)	2,560 KB
JPEG Large /Norm (Q 3)	1,689 KB
JPEG Small /Fine (Q 8)	1,277 KB

There are almost no JPEG artifacts visible at the Quality 8 setting, dropping down to Quality 6 we can start to see artifacts around the detail of dark lines, although at 100% view these are invisible. Quality 3 (the default for Normal compression) has a larger impact on image quality and I would recommend its use only when storage is very short. Overall the EOS-1Ds proves to have a very capable and mature JPEG compression algorithm that even at fairly heavy compression levels doesn't introduce too many artifacts. I really do like the way you can fine tune the JPEG compression setting to suit your needs and storage. Kudos Canon.

Tone curve

Just like the EOS-1D the EOS-1Ds has the ability to load custom tone curves. The curves defined for the EOS-1Ds have four control points which define the curve used to translate the RAW linear data into the final image (gamma space). Note that the modification of this curve now takes place on a logarithmic scale, this is much easier to work with and understand. You can modify color channels individually (R, G or B) or just luminance (RGB linked).

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) / Small, Fine JPEG

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