Canon XSi Image Quality

Saturation & Hue Accuracy
Accurate color with minor oversaturation of strong reds and blues.

Saturation. The Canon XSi pushes reds and blues just a bit, and undersaturates some yellows and greens, but , blues and some greens by quite a bit, but overall saturation is quite good. 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. Caucasian skin tones from the XSi lean toward the warm side. Some users would call this "a healthy glow"; we found it natural and pleasing. 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 Canon XSi showed a few small color shifts relative to the correct mathematical translation of colors in its subjects, but had excellent accuracy overall. Most noticeable was a shift in reds toward orange, and orange toward yellow, with some shifts in greens and cyans as well. Hue is "what color" the color is.

Saturation Adjustment
The Canon XSi has a total of nine saturation settings available, four above and two below the default saturation. This covers a very wide range of saturation levels, about as wide a range as you're likely to find photographically relevant, apart from special effects that are arguably better achieved in software. The fine steps between settings mean you can program the camera to just the level of saturation you prefer. Nice.

The table above shows results with the default as well as the two extreme saturation settings. Click on any thumbnail above, then click again to see the full-sized image.

Exposure and White Balance

Indoors, incandescent lighting
Good color with the Manual white balance setting, though warm results with Auto and Incandescent. Slightly below average positive exposure compensation required.

Indoors, under normal incandescent lighting, color balance was very warm with the Auto white balance setting. The Incandescent setting was better, but also on the warm side. (The XSi's Incandescent setting appears to be color-balanced for professional studio lighting, rather than the warmer household incandescent lights most US consumers have in their homes.) The Manual setting produced the most accurate results. In the end, the Incandescent setting was a bit too warm for our tastes, but some users may actually prefer this, as being more representative of the original lighting. The Canon XSi required a slightly less than average amount of positive exposure compensation here, at +0.7 EV. Despite the (very) slight warm cast, overall color with the Manual white balance setting looks quite good, though the blue flowers appear very purple, and the greens are a bit dark. (Many digital cameras reproduce these flowers with a dark, purplish tint, so the Canon XSi actually performs a little better than average here.) 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 colors overall, though a tendency toward a warm cast and slightly high contrast under harsh lighting. Better than average exposure accuracy.

Outdoors, the Canon XSi tended toward a warmer color balance, though overall color was generally pretty good. The XSi performed a bit better than average in terms of exposure, requiring slightly less than the typical amount of positive compensation we're accustomed to seeing among consumer digital cameras. (And the far-field shot of the house came out just about ideal at the XSi's default exposure setting.) The XSi's default contrast is a little high, producing washed-out highlights and dark shadows under the deliberately harsh lighting of our "Sunlit" portrait test shown above left. The camera's contrast and highlight tone priority settings do tame the highlights and shadows though (see below).

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

Resolution
Very high resolution, 1,600 ~ 1,650 lines of strong detail from in-camera JPEG, 1,700 ~ 1,800 lines from processed RAW file.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,650 lines per picture height horizontally, and about 1,600 lines in the vertical direction. Extinction didn't occur until about 2,300 lines horizontally, 2,500 lines vertically (results from 2X target are multiplied by 2). When processing the XSi's CR2 files using Adobe Camera Raw, we were able to extract more resolution, about 1,800 lines in the horizontal direction, and about 1,700 lines in the vertical. 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
Sharp images overall, though slight edge-enhancement artifacts on high-contrast subjects. Some minor noise suppression visible in the shadows.

Sharpness. The Canon XSi captures fairly sharp images overall, though some minor edge enhancement artifacts are visible on high-contrast subjects such as the crop above left. Note also that sharpness is set to slightly soft by default. 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 some minor noise suppression artifacts in the darkest areas of Marti's hair, though quite a few individual strands are visible in the lighter shadows. The camera's overall response here is better than average. 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.

RAW vs In-Camera JPEGs
As noted above, the Canon XSi does a pretty good job at balancing between sharpness and visible sharpening artifacts in camera JPEGs. As is usually the case though, a little more detail can be obtained from carefully processing RAW files, without additional artifacts. Take a look below, to see what we mean:

In the table above, mousing over a link at the bottom will load the corresponding crop in the area above. Examples include in-camera Fine JPEG, RAW file processed through Canon's Digital Photo Professional (DPP) software, and RAW file processed through Adobe Camera Raw version 4.4.1, then sharpened in Photoshop. (For the Canon XSi's images, I found best results with 250% unsharp masking with an 0.3 pixel radius.)

Note: ACR renders colors somewhat differently than either the XSi or the Canon software, so the greens in the trees are rather different. There's no mistaking the increase in detail though, regardless of changes in color or tone.

ISO & Noise Performance
Very low image noise, with relatively low noise even at the highest sensitivity setting.

The Canon EOS Digital Rebel XSi produced very low image noise overall. At ISO 800, noise was a little high, though with relatively little blurring in the finer details. Even at ISO 1,600, noise is lower than average, and fine detail is still pretty good. As noted above, the Canon Rebel XSi does a much better job than average in suppressing image noise without losing fine/subtle subject detail and its High ISO Noise Reduction setting does a good job at reducing chroma noise further, without impacting detail. An excellent performance, especially for a camera with a 12-megapixel APS-C size sensor. As always, see the Print Quality section below, to find out what the recommended maximum size print is at each ISO setting.

Extremes: Sunlit and low light tests
Very high resolution with strong overall detail, but slightly high contrast with strong highlights. Excellent low-light performance, great exposure to the lowest limits of our test, and the autofocus worked that low, even without the AF-assist light.

Sunlight. The Canon XSi produced high contrast with slightly washed-out highlights and deep shadows under the harsh lighting of the test above. However, shadow detail is pretty good. Marti's face was a little dim at the default setting, so we preferred the image with +0.3 EV of exposure compensation, despite the clipped highlights in her shirt. Compensation of +0.7 EV resulted in too many clipped highlights for our tastes. (In real life, 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.)

Contrast Adjustment
We really like it when a camera gives us the ability to adjust contrast and saturation to our liking. It's even better when those adjustments cover a useful range, in steps small enough to allow for precise tweaks. As was the case with its saturation adjustment, the Canon XSi's contrast setting meets both challenges very well.

At its lowest contrast setting, the Canon XSi did an excellent job of preserving highlight detail, maintaining fairly natural-looking (if just slightly pink) skin tones, and holding nice detail in the shadows. The XSi captures good color outdoors, though again, just slightly on the warm side. Overall, very good results here, especially when the contrast setting is tweaked.

The table above shows results with the default as well as the two extreme contrast settings. While you can see the extremes, it's hard to really evaluate contrast on small thumbnails like these, click on any thumbnail to go to the full-size image. The Canon XSi's contrast adjustment worked well, with little effect on color saturation. Contrast and saturation are actually fairly closely coupled adjustments, it's a good trick to be able to vary one with out the other changing as well. Canon did a good job here.

Canon's Highlight Tone Priority

The two shots above show the results with Highlight Tone Priority Off and On. The shots were shot in rapid succession, but you'll notice that minor movements by Marti mean that the shots aren't absolutely identical. As you can see from the crops, fewer highlights in the flowers are clipped, while shadow detail is simultaneously improved when Highlight Tone Priority is enabled.

Automatic Lighting Optimization

Unlike Highlight Tone Priority, we found relatively little effect from Canon's Automatic Lighting Optimization feature. At least on this test, there was almost no difference between shots with ALO on or off. We did see a slight improvement in detail and noise levels in the deep shadows, but had to really play with the image's tone curve to be able to see its effect. (It's possible that ALO might have more effect in the case of significant exposure errors, but we didn't test that situation directly.)

Low light. The Canon XSi performed very well on the low-light test, capturing usable images at the lowest light level (1/16 foot-candle), even with the lowest sensitivity setting (ISO 100). Noise increases as ISO goes up and light levels go down, but remains fairly low, even at higher sensitivities. There are no sign of hot pixels, even when NR is set to Off, but some very slight banding can be detected in the shadows at higher ISOs. Color balance looked very good with the Auto white balance setting. The camera's autofocus system was able to focus on the subject at less than the 1/16 foot-candle light level unassisted, and in complete darkness with the AF assist enabled. Keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any 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.) Digital SLRs like the Canon XSi do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality
Great print quality, good color, sharp 13 x 19-inch prints.

The Canon XSi's printed output is really impressive, able to output usable 16 x 20-inch prints at ISO 100. They're slightly soft, thanks to a bit of noise suppression and a low default sharpening setting, but really quite good. Contrast and detail increases for a more satisfying print with a 0.3 Radius, 100% Unsharp Mask in Photoshop. 13x19-inch prints are a little better, requiring less sharpening. ISO 200 shots print the same as 100, producing a good 16x20 or great 13x19. ISO 400 images do just fine at 13x19, and of course are better 11x14, but not by much. ISO 800 shots are still quite good at 11x14, with only a little chroma noise in dark areas. ISO 1,600 shots really look good at 11x14. Yes, there's some chroma noise in darker areas, and it becomes noticable in the bottles of the Still Life shot, but still not bad. At 8x10, that chroma noise is only noticeable on close inspection; though the contrast is increased somewhat.

Detail throughout the ISO range remains surprisingly strong. Canon has managed to increase the resolution while improving high ISO noise performance. I'd like to see a little more detail at the lower ISO settings, but you can raise in-camera sharpening to achieve that, or sharpen after. An excellent performance that should make you confident to shoot at any ISO setting, in just about any kind of light, Tungsten included.

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.)