Canon SD790 IS Exposure

Saturation & Hue Accuracy
Very nice overall color saturation and hue accuracy, with only slight oversaturation in some reds and blues.

Saturation. True to Canon form, the Powershot SD790 IS produced pretty good overall color. The camera did oversaturate strong reds and blues a little, which is actually normal among consumer digital cameras. Still, color was vibrant and pleasing across an array of subjects. Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life.

Skin tones. Here, with the color balanced properly for the light source, the SD790's skin tones were a hint warm, but quite natural. Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc.

Hue. The Powershot SD790 IS showed a few small color shifts relative to the correct mathematical translation of colors in its subjects. Cyan tones were pushed strongly toward blue, while oranges pushed toward yellow and yellows toward green. Still, overall color accuracy was quite good. Hue is "what color" the color is.

Exposure and White Balance

Indoors, incandescent lighting
Nearly accurate color with the Manual white balance, though Auto performance isn't too terribly off. Less than average positive exposure compensation was required.

Color balance indoors under incandescent lighting was slightly magenta in Auto white balance mode, while the Incandescent setting produced a much stronger pink cast. Manual mode was the most accurate overall, if a hint on the yellow side. Overall color here is quite good, with only slight purplish tints in the blue flowers. The Powershot SD790 IS required only a +0.7 EV exposure compensation boost to get a good exposure, which is less than average for this shot. Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.

Outdoors, daylight
Bright color outdoors, though high contrast exposure under harsh lighting.

Outdoors, the Canon Powershot SD790 IS performed fairly well, though high contrast creates hot highlights and deep shadows. Though the shirt is almost completely blown out in the +0.7 EV shot, this is the closest it gets to good skin tones without excessive highlights taking over. The SD790 IS does have an adjustable contrast setting, which is useful under conditions like these. Shadow detail is somewhat limited in both shots, partially from noise suppression and partially from interference from noise pixels. Overall color outdoors remains vibrant however, despite the extreme exposure conditions.

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Resolution
Very high resolution, 1,600 ~ 1,800 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,700~1,800 lines per picture height horizontally, though lines are really only clear to about 1,600 lines vertically. Extinction didn't really occur, though lines get fuzzy at around 1,900. Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Fairly sharp images overall, with only minor edge-enhancement on high-contrast subjects. Noise suppression limits detail in the shadows.

Sharpness. The Canon Powershot SD790 IS captures a lot of detail with pretty good definition and sharpness. Very slight enhancement artifacts are visible on high-contrast subjects such as the crop above left, but overall results are good. Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.

Detail. The crop above right shows moderate noise suppression, with darker areas of hair showing more limited detail. Individual strands merge in the darker shadows, losing definition. Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.

ISO & Noise Performance
Low to moderate noise at the normal sensitivity settings, though a jump in noise with strong blurring at the higher settings.

The Canon Powershot SD790 IS handles image noise well at its lower ISO settings, with minimal interference up to ISO 200. At ISO 400, image noise is slightly higher, with less visible fine detail as well. Where things really start to fall apart is at ISO 1,600, as the noise pattern is quite strong and affects detail and color balance. In an attempt to control the effects of noise, the SD790 IS limits resolution to 1,600 x 1,200 pixels at ISO 3,200, the highest setting, though the entire image is quite soft.

Extremes: Sunlit and low light tests
High resolution with strong overall detail, but high contrast and limited shadow detail. Good low-light performance, capable of capturing bright images in near darkness.

Sunlight. The Canon Powershot SD790 IS had some difficulty dealing with the deliberately harsh lighting in the test above, producing very high contrast with washed-out highlights and deep shadows. Shadow detail is limited, with the effects of noise suppression evident in the form of smudged detail in deep shadow areas. The strong highlights also hold onto minimal detail. The camera required about average compensation to get proper exposure of skin tones, at +0.7 EV, but at the expense of detail in the white shirt. Consider reducing the contrast setting with the Powershot SD790 IS, and be sure to use fill flash in situations like the one shown above -- it's better to shoot in the shade when possible.

Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here.)

Low light. The Canon Powershot SD790 IS performed well on the low-light test, capturing bright images almost at the lowest light level with the lowest sensitivity setting (ISO 80). Images were bright all the way to 1/16 foot-candle at ISOs 200 and up. Color balance was pretty good with the Auto white balance setting. The camera's autofocus system worked well also, as it was able to focus on the subject down to just under the 1/8 foot-candle light level unassisted, and down to the darkest light level with the AF assist enabled. Keep in mind that the longer shutter times here demand the use of a tripod to prevent blurring from camera movement. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)

How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) For such applications, you may have better luck with a digital SLR camera, but even there, you'll likely need to set the focus manually. For information and reviews on digital SLRs, refer to our SLR review index page.

Coverage and Range
A slightly dim flash overall. EV compensation had no effect on standard flash shots.

Coverage. Flash coverage was uneven at wide angle, but more even at telephoto. In the Indoor test, the Powershot SD790 IS' flash underexposed our subject just a little at its default setting, but the camera's EV adjustment had no effect on the standard flash exposure. The camera's Slow-Sync flash mode produced brighter and more even results, though with a stronger pinkish-orange cast from the room lighting. Here, the +0.3 EV exposure produced the best results.

ISO 100 Range. At wide angle, flash shots at ISO 100 remained fairly bright out to a distance of about 9 feet, decreasing in brightness slightly from that point on. At full telephoto and ISO 100, the target remained at the same brightness to about 7 feet before decreasing with each foot of distance.

Manufacturer Specified Flash Test. In the wide angle shot above, the Powershot SD790 IS performs almost as Canon says it will, though it boosted ISO to 250 to compensate. At telephoto, the camera again boosted ISO, this time to 200. Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims.

Print Quality
Good print quality, good color, sharp 11x14 inch prints at ISO 80 and 100. ISO 400 images are soft but still usable at 11x14, ISO 800 shots are usable at 8x10.

The Canon SD790 IS had enough resolution to make sharp 11x14-inch prints at ISO 80 and 100. 13x19 and 16x20-inch prints were reasonable, but detail was soft at both sizes. ISO 200 shots are good at 11x14, with good color and detail, but with noticeable chroma noise in the shadows. ISO 400 shots are soft at 11x14, but most of the chroma noise is gone. At 8x10 detail returns; contrast is also a little higher at ISO 400. ISO 800 shots are grainy, but not bad at 8x10; at 5x7 they look pretty much normal. ISO 1,600 shots are usable at 5x7, but not much better at 4x6. They're noticably grainy, but acceptable. ISO 3,200 shots are blurry and poor at 4x6 inches, so steer clear of this Scene mode. Pretty good results overall.

Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 studio printer, and on the Canon iP5200 here in the office. (See the Canon PIXMA Pro9000 review for details on that model.)