JPEG Quality / Image Sizes

Standard Test Scene

The Digital IXUS v supports nine combinations of JPEG compression levels (quality) and image size. You can select from one of three image sizes; 1600 x 1200, 1024 x 768 or 640 x 480 and three different JPEG compression levels; Super-Fine (5 bpp), Fine (3 bpp) and Normal (2 bpp). The IXUS 300 does not have an uncompressed TIFF or RAW mode.

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:

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

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

1600 x 1200

937 KB
581 KB
276 KB

1024 x 768

424 KB
270 KB

137 KB

640 x 480

189 KB

If you look closely at the above samples you can see a clear difference between each compression level and the associated loss of detail / increase in artifacts. Probably 90% of the time you'd use 1600 x 1200 Super-Fine.

Picture Effects

The Digital IXUS v only has one picture effect and that's a black and white mode. You access it by setting the white balance to black and white, here's a sample of the difference between normal colour mode and the black and white mode.

Normal colour 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 v features a 2 x optical zoom and beyond that digital zoom levels of 1.25x, 1.5x, 2.0x and 2,5x.

Digital Zoom is implemented by 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.

Zoom: 2 x (70 mm optical, no digital)
Zoom: 3 x (70 mm optical, 1.5 x digital)
Zoom: 5 x (70 mm optical, 2.5 x digital)

Digital Zoom can be useful when shooting at lower resolutions: Shooting XGA size images, digital zoom of 1.5x or less would not require any enlargement of pixels. At VGA size, any digital zoom of 2.5x or less would not require any enlargement of pixels.