JPEG/RAW Image Size & Quality

The G5 provides four image size options in combination with three JPEG quality settings. In addition to these there is also the RAW format (losslessly compressed) which can be considered a 'digital negative' as it contains the unprocessed data as it comes directly from the CCD (as well as information about camera settings).

Standard Test Scene

To give an impression of what some of the combinations of image size and quality produce the table below is a cross reference of some of them:

• 2592 x 1944 RAW
• 2592 x 1944 Super-Fine
• 2592 x 1944 Fine
• 2592 x 1944 Normal
• 1600 x 1200 Super-Fine
• 1024 x 768 Super-Fine
• 640 x 480 Super-Fine

Images below are cropped 240 x 100 area of the image magnified 200% (nearest neighbour).

	2592 x 1944
RAW	5,495 KB Canon RAW (.CRW) - not available for download
Super Fine JPEG	2,709 KB
Fine JPEG	1,695 KB
Normal JPEG	801 KB
	1600 x 1200
Super Fine JPEG	1,173 KB
	1024 x 768
Super Fine JPEG	494 KB
	640 x 480
Super Fine JPEG	199 KB

As we have come to expect Canon's "Super-Fine" setting is very clean and as near to "lossless JPEG" as you could ask to get, it uses a very mild compression ratio and exhibits no visible JPEG artifacts or loss of detail. Higher compression ratios are available with the Fine and Normal settings, however these are also relatively clean, certainly compared to some other manufacturers algorithms. Canon also uses a quality interpolation algorithm when producing the downsampled 'lower resolution' images, they are clean and smooth with no hard jaggies. The G5 of course provides a RAW mode which in effect gives you a 'digital negative' which you can 'develop' with different settings (white balance, sharpening, exposure compensation etc.) than were originally set.

Custom Effect

The G5 has a dedicated 'Effect' menu which allows you to apply canned image processing settings to the images before they are stored, these include effects such as black and white, sepia, low sharpening and vivid color. In addition there is a Custom Effect setting which gives you control over three aspects of image processing. You can alter the sharpening, contrast and saturation of images. Although these settings are available in RAW mode they are not applied to the image in-camera but are stored in the RAW image header as the default settings for Canon's File Viewer Utility.

My only gripe must be that while it's good to see control over image processing (to be frank we expect it with this level of camera) I would have been much happier to see a greater latitude of adjustment, +/-3 levels at least.

Contrast and Saturation

Contrast -1	Contrast 0	Contrast +1
Saturation -1	Saturation 0	Saturation +1

Sharpening

Sharpening -1

Sharpening 0

Sharpening +1