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Descriptions concerning the number of pixels in the image sensor

According to the Guidelines, when describing the number of pixels in the imaging device in a catalog, etc.,
both the total number of pixels (“E” in the diagram below) and the number of effective pixels (“D” in the
diagram below) should be indicated; and if only one value is to be indicated, it is better to indicate the number
of effective pixels. However, for digital cameras that are released to the market in September 2001 and later,
the Guidelines have been changed. For digital cameras released to the market in September 2001 and later,
priority must be given to the indication of the number of effective pixels* (as defined by “A” or “B” in Fig. 2-
8); if the number of pixels other than effective pixels is also to be indicated, that number must be indicated in
such a way that it will not be confused for the number of effective pixels.
Under these revised guidelines, a sample description of the number of pixels in the CCD for the PowerShot
G2 is shown below. Note that when the number of pixels is given in “megapixels,” the number of effective
pixels may be rounded off to one decimal place.

A : Effective pixels of camera (exclude ring pixels)
B : Effective pixels of camera(include ring pixels)
C : Max. pixels for use

(guaranteed by the manufacturer of the device)

D : Effective pixels of sensor

(Total pixels minus optical black)

E : Total pixels

A
B
C

D
E

123456789012345678901234567890121234567890123456789012345678901212345

123456789012345678901234567890121234567890

Image circle of lens

Optical black

Ring pixels

Number of effective pixels

Formerly, the number of effective pixels indicated the total number of pixels among all of pixels on the imaging
device that could actually be used for photoelectric conversion (i.e., the number of pixels remaining after
optical black is excluded from the total number of pixels). With the revisions, however, it is important to note
that the number of effective pixels is now defined as the number of pixels that are actually used for imaging.

Therefore, when ring pixels (the minimum number of
pixels surrounding the image area that are needed for
filter processing while still allowing the processing to
be performed efficiently) are not included, the number
of effective pixels is identical to the maximum number of
recording pixels (when interpolation, etc., is not used).
If ring pixels are included, the number of effective
pixels is slightly larger than the maximum number of
recording pixels.

Reference

Fig. 2-8 Pixel structures of image sensor

Partial change to the content of the “Guidelines for Descriptions for Digital Cameras in Catalogs,
Etc.”

Recently, some revisions were made to the “Guidelines for Descriptions for Digital Cameras in Catalogs, Etc.”
published by the Digital Camera Committee of the Japan Camera Industry Association. These revisions are
described below.

- Reading method
- Chip size
- Effective pixels
- Total pixels
- Filter arrangement

: Interline
: 8.10 mm (H) X 6.64 mm (V) 1/1.8 inches
: Approx. 3.95Mpixels (4Mpixels) (2,308 (H) X 1,712 (V))
: Approx. 4.13Mpixels (2,384 (H) X 1,734 (V))
: Primary Bayer