Canon PowerShot G1, Service Manual

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G9
-New RAW mode
Canon has greatly improved the RAW application employed in the PowerShot A series, developing the PowerShot G1’s
New RAW mode. The advantage of RAW modes is that they allow users to obtain original image data, since image data
is recorded to memory from the CCD without any image processing. With RAW mode images, users can process images
as they desire, setting and changing the parameters, “developing”
*1
the RAW data into an image., setting and changing
the parameters. We adopted the reversible image compression
*2
method for the PowerShot G1, so now RAW images
require only approximately 60% the amount of memory necessary for the PowerShot A Series. The PowerShot G1 also
enables playback of images on the LCD monitor or an external monitor. (Currently, the only digital cameras capable of
this are the EOS D30, PowerShot G1 and the PowerShot Pro90.)
The RAW image data is processed by ZoomBrowser EX 2.4, ImageBrowser 1.4, TWAIN Driver 3.4 and Plug-In Module
3.4 application software, which are bundled with the PowerShot G1. Users can adjust image parameters such as white
balance, contrast, sharpness and color saturation. The adjusted image data is stored in TIFF format (TIFF is the default
format, but users can also choose among BMP, JPEG, and others.).
While some competitors’ models use TIFF format as a high image quality mode, most of these models record images as
8 bit data after processing white balance, ganmma-compensation, etc. Files of this type (RGB TIFF format) are four times
*3
the size of the new RAW mode type files.
Moreover, image quality declines when these images are processed on PC’s using retouch software, because image
processing is carried out twice.
*1
In the process of developing, RGB signals are created from RAW data.
*2 In this method, original image data can be completely restored, as opposed to non-reversible compression methods such
as JPEG, whose original data cannot be restored.
*3 A comparison of data file size between RAW and TIFF
-PowerShot G1’s number of recording pixels: 2048X1536
RAW data file size: 2048X1536X10 (quantization of each pixels)X0.61 (data compression) 8 (convert to byte) 2.5 MB.....
1
TIFF format filesize :2048X1536X 8 (quantization of each pixels)X 3 (separate to RGB) 8 (convert to byte) 9.4 MB......
2
1 2 =
1/3.76 1/4
Table 2-5 Comparison of each file format.
Fig. 2-5 New RAW and TIFF developing.
ZoomBrowser/ImageBrowser
TWAIN/Plug-In
Thumbnails
RAW
Camera
window
Displayed in
thumbnails
Download
Display
Image editing
(WB, contrast, etc.)
File conversion
TIFF (Default)
BMP/JPEG/
Flash Pix
Application
File conversion
TIFF/BMP/JPEG…
Browser
area
Developing
Image editing
(WB, contrast, etc.)
Developing
Acquire
-A/D conversion
-Reversible
compression
Processing by camera
Recording
as RAW
Recording
as TIFF
RAW data
from CCD
TIFF
New RAW
Retouch by
application
Processing by user (PC)
(The images are created by user)
Processing by camera
(The images are created by cameras.)
Processing by user (PC)
-A/D conversion
-Developing
RAW data
from CCD
File format Image quality File size Compatibility Playback with camera Features
RAW (old)
X- X X
(Thumbnail only) High image quality, however impossible to set to parameters of image quality
RAW (new)
X O
Possible to set parameters of image quality to original data.
Sup er Fine
O O
High image quality, however not reversible compression/
imp ossible to set to parameters of image quality
Fine O O O O Small file size, however not reversible compression
TIFF X O O High image quality, however large file size./impossible to set to parameters of image quality