Canon PowerShot G2, Руководство по обслуживанию

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1-6
2 Features
2-1 High Image Quality
l
High-resolution, 1/1.8-inch CCD with 3.95 million (4M) effective pixels (4.13 million total pixels)
=> Refer to page 1-15.
The PowerShot G2 will be equipped with a 1/1.8-inch CCD with 3.95 million (4M) effective pixels (4.13
million total pixels) to be released this fall, giving it the greatest number of pixels in the compact camera class.
This CCD is identical in size to its predecessors with 3.34 million (total) pixels, but is able to accommodate
4.13 million (total) pixels because the individual pixel size (cell size) has been reduced from 3.45[micron]m to
3.125[micron]m.
Table 2-1* shows the calculated resolution for each print size, given that the PowerShot G2 will use 2272 x
1704 recording pixels in large mode. As a result, postcard size will, as an example, produce a print with a
resolution of 6.3 lp/mm, which is close to the limits of visual acuity in humans. Even large (A4) size will
produce a print with a practical resolution of 3.7 lp/mm.
*
The resolutions indicated are derived from the number of pixels in the CCD; in actual practice, these resolutions
will be affected by the printer resolution.
l Primary color filters with excellent color reproduction
As in the IXY DIGITAL 300/200 and the PowerShot A20/A10, primary color-type filters have been adopted
for the PowerShot G2 as the CCD on-chip filters for colorization.
With the primary color-type filters, filters for the
three colors (R, G, and B) are positioned on the
CCD in a regular pattern. Although this type of filter
offers excellent color reproduction, the principles
behind it result in inferior performance in terms of
resolution and the illumination S/N ratio as compared
to complementary color-type (Cy, Mg, Ye, G) filters.
In order to address this shortcoming in regards to
resolution, signal processing based on a newly
developed algorithm that has been implemented in
the new imaging engine results in a reduced noise
component, which effectively results in higher resolution.
In regards to the illumination S/N ratio, improvements were made to the filters in order to increase the
efficiency with which light is used, resulting in an illumination S/N ratio that is on a par with complementary
color-type filters while still maintaining excellent color reproduction characteristics.
Table 2-1 Print Sizes and Resolutions Produced by PS G2 (Calculated Values)
Fig. 2-1 Color Filter Color Arrangement
Complementary color type
Primary color type
Postcard size
(148mm x 100mm)
Service (E) size
Card size
(86mm x 54mm)
6.3 lp/mm
10.8 lp/mm 7.8 lp/mm
Cabinet size
(165mm x 120mm)
Large (A4) size
(254mm x 203mm)
5.6 lp/mm 3.7 lp/mm
(120mm x 82mm)