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Image Size / JPEG Quality


Standard Test Scene

The Digital IXUS keeps things simple by only having three different quality / resolution settings, at the top end we have Large / Super-Fine which is 1600 x 1200 and weighs in at around 1,700 KB, a very low compression JPEG (6 bits-per-pixel), next comes Large / Fine (1600 x 1200) mode, which most people will use most of the time produces a 720 KB JPEG (3 bits-per-pixel) finally there's Small 640 x 480 at around 130 KB (3 bits-per-pixel) an image.

To give an impression of what each combination of image size and quality produces the table below is a cross reference of image size against quality with an original image available for each, all images were shot within seconds of each other of the same subject.

Crops below have been expanded 200% for clarity (no resampling).


1,742 KB

611 KB
Large (1600 x 1200) / Super-Fine
 
Large (1600 x 1200) / Fine
 

133 KB
 
Small (640 x 480) / Fine
 
 

With the addition of the Super-Fine mode (something we first saw in the S10) Canon have done away with the need for a TIFF or RAW mode (a bit overkill on a compact camera like this), if the camera did have a TIFF mode it would be very difficult to distinguish between Super-Fine and TIFF.


Picture Effects

The Digital IXUS only has one picture effect (post image filter) and this is black & white mode, strangely in black & white mode the image isn't perfectly gray it has (get ready for it Canon Talk) a very slight magenta cast (R+2, G+0, B+2)... odd. The filter also seems to push image contrast in an attempt to produce a more "arty" shot.. I'd personally prefer to alter the images out of the camera..


611 KB

435 KB
Large / Fine full colour
 
Large / Fine Black & White


Digital Zoom

Readers of my reviews will know I'm not a huge fan of digital zoom as it's often a badly implemented and seldom used (by owners) marketing "ploy" to sell cameras which don't have an optical zoom. The Digital IXUS does indeed have optical zoom, and has two digital zooms which can be used on top of the standard 2x optical zoom. (IF digital zoom is enabled) Once you go past the maximum optical zoom the camera will switch to 2x digital zoom and optical zoom will go back to full wide, zooming further uses the optical zoom smoothly until you reach the limit again and the camera will switch to 4x digital zoom..

They are however simply cropping (selecting the mid part of the image) and sampling-up, the only advantage in doing digital zoom inside the camera is (a) if you don't have any photo software to magnify (and interpolate) the image or (b) to digitally zoom without zooming the JPEG artifacts.


611 KB

435 KB
Full Optical Zoom, No Digital Zoom
 
Full Optical Zoom, 2x Digital Zoom

941 KB
 
Full Optical Zoom, 4x Digital Zoom
 
 

Well, digital zoom isn't something you'll use every day (or I'd recommend you use every day), as you can see the results can be pretty scary.


Internal Flash

The internal flash unit in the Digital IXUS seems to be identical to its APS brother (IXUS II), for those who've asked me by e-mail, yes it does fire twice in succession for a normal shot. Maximum ranges are: Wide 3 m (10 ft), Tele 2 m (7 ft).

Skin tone test. Ooh.. Well, looks as though the background threw out the white balance on this shot, skin tones have come out with a blue (cold) cast. Here it is again without any background, skin tones are much better, but my feeling is that the white balance should be locked for a flash shot.
 

Colour test chart shot @ 15 degrees off horizontal (to decrease reflection). Well metered, obvious cyan cast.

 


Panorama / Photo Stitch mode

The Digital IXUS features two Photo Stitch modes, one from left to right and another from right to left. I'd like to have seen vertical / square stitch modes too, but then I'm always hoping for more...

When using the PhotoStitch mode the camera displays the last quarter of the previous image to help alignment of the next frame, to ensure proper matching of the stitched images the camera locks exposure and white balance to the first exposure.

The Digital IXUS also comes with Canon's own Photo Stitch software (both Windows & Mac), it made a fairly good job of stitching four images together to produce the panorama below. Just for reference I included the same images stitched using PanaView Image Assembler (may personal favourite stitching software).


Stitched using Canon PhotoStitch, originally 4 images


Stitched using PanaView Image Assembler, originally 4 images

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