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Image Quality

Image quality is excellent, with resolution as-good-as if not better than the leading digicam's on the market. Colour balance and exposure was very good (if for a lack of spot measuring). You should also 'see with your own eyes' by taking a browse through the samples gallery.

Canon's approach to the CCD filter

On the Pro 70 Canon have used an alternative to the usual RGBG colour filter this time they've used CYGM. The coloured filter which is painted onto the surface of the CCD (dyes) is coloured as shown in the diagram, cyan, yellow, green and magenta.

The individual colour for each pixel is again calculated based on the values of it's neighbours but the algorithm here is a little more complicated (subtractive) than the standard Bayer pattern.

On their (Panasonic) 1536 x 1024 camera using Canon's pattern the following is true:

768 x 512 pixels are CYAN
768x 512 pixels are YELLOW
768x 512 pixels are GREEN
768x 512 pixels are MAGENTA

Canon's uncompressed format

Canon have also worked out a novel and space saving way to store uncompressed images, you just record the exact values of the pixels from the CCD and let your PC (in this case their TWAIN driver) do the interpolation back to a full colour image.

All the CCD RAW file contains is the colour level value (10-bits in Canon's case) for each 1536 x 1024 pixel instead of 24-bits for each 1536 x 1024 pixel (as in a TIFF file).

Equivalent files sizes for a 1536 x 1024 image in 'uncompressed' formats:

CCD RAW: 1.9Mb
TIFF: 4.5Mb

Noted image artifacts / errors

In some instances there was a slight colour moire pattern on fine detail:

Example of colour moire

Sometimes the camera did have problems with overexposure (or it could be a CCD effect called 'binning') against a bright background, but this effect can also be found on many other digital cameras:

Click for original image

There was also a slight colour shift problem between taking an image as JPEG and taking it as CCD RAW. This was concluded by Canon to be the fact that the CCD RAW images are white-balanced in the TWAIN driver where as the JPEG images are white-balanced in the camera. This problem would probably be corrected in a later version of the TWAIN driver.

(click on any of the below for larger image)

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