Canon PowerShot G1 Service Manual page 15

-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"
the parameters. We adopted the reversible image compression
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
the size of the new RAW mode type files.
*3
Moreover, image quality declines when these images are processed on PC's using retouch software, because image
processing is carried out twice.
In the process of developing, RGB signals are created from RAW data.
*1
*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)
TIFF format filesize :2048X1536X 8 (quantization of each pixels)X 3 (separate to RGB)
1 2 =
1/3.76 1/4
New RAW
Processing by camera
-A/D conversion
RAW data
-Reversible
from CCD
compression
TIFF
-A/D conversion
RAW data
-Developing
from CCD
Processing by camera
(The images are created by cameras.)
File format Image quality File size Compatibility Playback with camera
RAW (old) X-
RAW (new)
Super Fine
Fine O O
TIFF X
ZoomBrowser/ImageBrowser
RAW
Recording Download
as RAW
Browser
area
Display
TWAIN/Plug-In
Recording
Retouch by
application
as TIFF
Processing by user (PC)
X X (Thumbnail only) High image quality, however impossible to set to parameters of image quality
X O Possible to set parameters of image quality to original data.
O O
High image quality, however not reversible compression/
impossible to set to parameters of image quality
O O Small file size, however not reversible compression
O O High image quality, however large file size./impossible to set to parameters of image quality
Table 2-5 Comparison of each file format.
the RAW data into an image., setting and changing
*1
method for the PowerShot G1, so now RAW images
*2
8 (convert to byte)
8 (convert to byte)
Processing by user (PC)
(The images are created by user)
Displayed in
Developing
thumbnails
Image editing
(WB, contrast, etc.)
Camera
window
Developing
Thumbnails
Image editing
(WB, contrast, etc.)
Fig. 2-5 New RAW and TIFF developing.
Features
G9
2.5 MB.....
2
9.4 MB......
File conversion
TIFF (Default)
BMP/JPEG/
Flash Pix
Application
Acquire
File conversion
TIFF/BMP/JPEG...
1