Fuji Super CCD

From Camera-wiki.org
Jump to: navigation, search

Fuji's proprietary Super CCD design of CCD image sensor uses an unconventional pixel layout, whose benefits have been a subject of some dispute.

This design arranges the actual photo-sensor pixels in an diamond array. This gives them some benefits in laying out the ancillary electronics on the chip, and means that each photo-sensor is physically larger than would be possible in a conventional rectangular array. Larger photo-sensors means lower noise (for any given technology) and generally higher colour quality.

However, to be useful, the camera has to produce pictures in standard formats (like TIFF and JPEG), all of which require that the image be represented as a rectangular array of pixels. Fuji handles that by interpolating up to a rectangular array twice the size of the octagonal structure of the actual sensor. Thus many of the early Fuji cameras using the Super CCD have a maximum image resolution setting of twice the number of photo-sensors on the imaging chip. Fuji removed this ability in later models, possibily believing the confusion and increased file sizes weren't worthwhile for the small increase in overall image quality being offered by the full interpolarated output. Ironically, this makes Super CCD based cameras the only ones where digital zoom is advantageous in image quality terms over simple cropping.

Resolution tests with conventional lens test charts tend to show Super CCD cameras as having slightly more resolution than conventional sensor cameras (but nowhere near twice the resolution). However, it's widely believed that the unusual array has simply improved resolution on vertical and horizontal lines, heavily featured in conventional lens test charts, at the cost of resolution on diagonal lines.

Unfortunately, with some early models Fuji marketing had attempted to market the maximum file size as the actual resolution, causing a certain amount of bad feeling among digital camera users and confusing camera reviewers into making invalid comparisons with higher megapixel cameras to the Super CCD camera's detriment.

Two series of SuperCCDs are used in Fujifilm's cameras: The SR type with two different pixel sizes, or the HR type with just one pixel size.