Canon G7 X Image Quality


Color

Saturation & Hue Accuracy
Typical saturation levels with good hue accuracy, though yellows were a little problematic.

In the diagram above, the squares show the original color, and the circles show the color that the camera captured. More saturated colors are located towards the periphery of the graph. Hue changes as you travel around the center. Thus, hue-accurate, highly saturated colors appear as lines radiating from the center. Click chart for a larger image.

Saturation. The Canon G7 X produced fairly accurate saturation levels overall, with only mild to moderate oversaturation in reds, greens, browns, purples and blues. Bright yellow, aqua and cyan were undersaturated by relatively small amounts. Mean saturation at base ISO is 111.4%, or 11.4% oversaturated, which is about average these days. Overall, the Canon G7 X's images appear to have pleasing saturation levels and you can always adjust saturation using the camera's "My Colors" options. 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. With Auto white balance in simulated daylight, the Canon G7 X rendered lighter Caucasian skin tones just a touch yellow and flat. Manual white balance produced more pleasant, pinkish skin tones. 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 PowerShot G7 X produced a few color shifts relative to the correct mathematical translation of colors in its subjects, most visibly pushing cyan toward blue (probably for better-looking skies), red toward orange, and yellow toward green. Mean "delta-C" color error after correcting for saturation at base ISO was 4.57 which is better than average, though the shift and reduced saturation in yellows was noticeable in some of our test shots. Hue is "what color" the color is.

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

Sensor

Exposure and White Balance

Indoors, incandescent lighting
Better than average color balance with Auto, much too warm with Incandescent, but very good with Manual white balance setting. Average exposure accuracy.

Auto White Balance
+0.3 EV
Incandescent White Balance
+0.3 EV
Manual White Balance
+0.3 EV

Color balance indoors under incandescent lighting was pretty good with the Auto white balance setting, with just a hint of a magenta tint. The Canon G7 X did much better here than the majority of digital cameras we've tested. The Incandescent white balance option was much too warm, though, resulting in a strong orange cast. The Manual white balance setting was pretty accurate, but a touch cool with a slight bias towards cyan. The PowerShot G7 X's exposure system handled this lighting well, requiring a typical amount of exposure compensation (+ 0.3 EV) 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
Slightly cool colors, with high default contrast. Above average exposure compensation required.

Manual White Balance,
+1.0 EV
Auto White Balance,
Auto Exposure

The Canon PowerShot G7 X performed fairly well in the simulated outdoor lighting of our "Sunlit" Portrait shot. Although above average exposure compensation of +1.0 EV was needed to keep the mannequin's facial skin tones bright, the number of blown highlights in her shirt and the flowers is actually not bad for such a compact camera, and detail in the shadows is pretty good. The G7X underexposed our outdoor far-field shot at default exposure a bit producing some very deep shadows, but as a result very few highlights were blown. Luminance noise is a bit high in deep shadows, however chrominance noise is well controlled. Color outdoors was good with the Auto white balance setting, just a touch cool, though the camera rendered skin tones a little too flat and yellow, so we preferred Manual white balance here for our "Sunlit" Portrait shot.

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

Resolution
About 2,500 lines of strong detail from in-camera JPEGs, a little higher from converted RAW files.

In-camera JPEG:
Strong detail to
~2,500 lines horizontal
In-camera JPEG:
Strong detail to
~2,500 lines vertical
ACR converted RAW:
Strong detail to
~2,600 lines horizontal
ACR converted RAW:
Strong detail to
~2,600 lines vertical

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,500 lines per picture height in the horizontal direction, and to about the same in the vertical direction in JPEGs straight out of the camera. Extinction of the pattern occurred just past 3,000 lines in the horizontal direction, and past 3,200 lines in the vertical direction. Adobe Camera Raw was able to extract perhaps 100 extra lines of resolution in both directions as well as extend total extinction to between 3,500 and 3,600 lines. 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, detailed images overall, though with some visible sharpening artifacts on high-contrast subjects. Noise suppression limits detail in low contrast areas.

Good definition of high-contrast
elements, with some visible
edge enhancement.
Subtle detail: Hair
Noise suppression blurs
detail in areas of subtle contrast,
as in the darker parts of hair here.

Sharpness. The Canon PowerShot G7 X captures fairly sharp JPEG images at default settings, though some edge enhancement artifacts are visible on high-contrast subjects such as the noticeable halos around lines and text in the crop above left. Sharpening isn't as overdone as some cameras, but enthusiasts might want to shoot with a lower sharpening setting and apply additional sharpening in post processing, or shoot RAW for complete control over sharpening. 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 significant smudging of low contrast detail due to noise suppression, as individual strands of hair are blurred together in midtones and shadows, but performance here is still better than average for a compact digicam. 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 G7 X produces fairly sharp, detailed in-camera JPEGs at base ISO. But with a good RAW converter, more detail can often be extracted with fewer sharpening artifacts. See below:

Base ISO (125)
Camera JPEG, defaults
RAW via Adobe Camera Raw

In the table above, we compare an in-camera JPEG taken at base ISO using default noise reduction and sharpening (on the left) to the matching RAW file converted with Adobe Camera Raw 8.7 using default noise reduction with some strong but tight unsharp masking applied in Photoshop (300%, radius of 0.3 pixels, and a threshold of 0).

Looking closely at the images, ACR extracts additional detail that isn't present in the JPEG from the camera, particularly in the red-leaf swatch where the thread pattern is likely treated as noise by the JPEG engine. Fine detail in the mosaic crop is also slightly improved, but as is often the case, more noise can be seen in the bottle crop. You can of course apply stronger noise reduction (default ACR NR used here) to arrive at your ideal noise versus detail tradeoff. Color was improved as well, with ACR removing much of the yellow-to-green shift in the JPEG. And, as expected, sharpening haloes aren't nearly as strong as the default camera output. Still, in-camera default JPEG processing isn't too bad, but as usual you can do noticeably better with a good RAW converter.

ISO & Noise Performance
Very good high ISO performance for a camera its size.

Default Noise Reduction
ISO 125 ISO 200 ISO 400
ISO 800
ISO 1,600
ISO 3,200
ISO 6,400 ISO 12,800

The PowerShot G7 X performed well here for its size, though not as well as some direct competitors, however that's mostly due to JPEG processing. ISO 125 and 200 are pretty clean and detailed but lack crispness, and ISO 400 already shows some significant softening due to strong noise reduction. ISO 800 is noisier and softer from more aggressive noise reduction, and ISO 1600 is softer still. Image quality drops off rapidly above ISO 1600, with increasing luma noise as well as stronger blurring from noise reduction, though chroma noise is fairly well-controlled.

High ISO performance is better than most compact cameras with smaller sensors, but the G7 X's JPEG engine does not appear to make the most of its larger, 1-inch type sensor producing somewhat soft images already at moderate ISOs. Note that the G7 X offers three levels of noise reduction (Low, Standard and High), and these shots were taken using the default Standard setting. The good news is that noise in the G7 X's RAW files is very competitive with other 1-inch sensor models, so for better high ISO performance, we recommend shooting in RAW format.

Of course, the impact of noise and detail loss are highly dependent on the size the photos are printed at, and pixel-peeping on-screen has surprisingly little relationship to how the images look when printed: See the Print Quality section below for recommended maximum print sizes at each ISO.

Extremes: Sunlit and low light tests
Pretty good dynamic range for its class. Good low-light performance, capable of capturing bright images in near darkness at all ISOs.

+0.3 EV +0.7 EV +1.0 EV

Sunlight. The Canon PowerShot G7 X did fairly well under the deliberately harsh lighting in the test above. To keep facial tones bright, +1.0 EV compensation was required, which led to some clipped highlights in the mannequin's shirt and flowers, but not as many as expected for its size. Some may prefer the +0.7 EV setting for its reduced highlight clipping, but we found the face a bit too dim. Detail is quite good in the shadows at +1.0 EV, though very deep shadows are a little grainy and posterized, though chroma noise is well controlled. Very good results in harsh lighting for such a compact camera, but consider using fill flash in situations like the one shown above; and 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.)

Outdoor Portrait i-Contrast Series (+0.7 EV)
i-Contrast
Setting:



DRC Off
(Default)



DRC 200%


DRC Auto


Shadow
Correct



As part of the G7 X's Intelligent Contrast (i-Contrast) feature, the camera has "Dynamic Range Correction" to help tame highlights, and "Shadow Correct" to bring out more shadow detail.

Above are examples of our challenging "Sunlit" Portrait scene shot with the G7 X's two available Dynamic Range Correction settings, plus Shadow Correct. Mouse over the links to the right to compare, and click on the links to get to the full-resolution images.

As you can see, highlights were toned-down with the DR 200% setting but results with DR Auto were practically identical to the Off setting, perhaps because relatively few highlights were blown to begin with. Shadow Correct also worked as expected, boosting shadows without impacting highlights too much, leading to the best overall exposure for this series.

Note that Dynamic Range Correction may boost ISO depending on your current setting, so more noise and/or stronger NR may be visible with it enabled. (In our samples above, DR 200% used ISO 250, while DR Auto and Shadow Correct left ISO at 125.)

Far-field i-Contrast Comparison

Above, you can see the effect of the available i-Contrast settings on our Far-field shot. Here, DRC Auto and 200% both made a difference, but it was pretty subtle. Shadow Correct on the other hand made quite a difference, boosting midtones and shadows while maintaining highlights.


Face Detection Examples
Aperture Priority
0 EV
Portrait Mode
0 EV
Smart Auto
0 EV

The table above shows results with the default exposure using Aperture Priority AE, as well as with Portrait mode, and Smart Auto. As you can see, the G7 X's face detection in Portrait and Smart Auto modes both increased exposure dramatically compared to the default exposure in Aperture Priority mode, going from very underexposed to bright images. Portrait mode selected an aperture of f/2.8 instead of f/5.6 we used in Aperture Priority but kept the ISO at 125, while Smart Auto selected f/4 with a boost in ISO to 250.

Dynamic Range Analysis (RAW mode)
While we once performed our own dynamic range measurements based on in-camera JPEGs as well as converted RAW images (when the camera was supported by Adobe Camera Raw), we've switched to using DxO Labs' results from their DxOMark website. As technology advanced, the dynamic range of modern high-end cameras in some cases exceeded the range of the Stouffer T4110 density scale that we used for our own measurements. DxO's approach based on RAW data before demosaicing is also more revealing, because it measures the fundamental dynamic range of the sensor, irrespective of whatever processing is applied to JPEGs, or to RAW data by off-the-shelf conversion software.

In the following, we use DxO's "Print" dynamic range results, which are scaled based on camera resolution. As the name suggests, this scaling corresponds to the situation in which you print at a given size, regardless of how many megapixels the camera might have. (In other words, if you've decided to make a 13x19 inch print, that's the size you're printing, whether the camera's resolution is 16 or 300 megapixels.) For the technically-minded, you can find a discussion of the reasoning behind this here on the DxOMark website. Also note that DxO Labs uses a signal-to-noise (SNR) threshold of 1 when defining the lower boundary of acceptable luminance noise in their dynamic range measurements, which corresponds to the "Low Quality" threshold of the Imatest software we used to use for this measurement.

Here, we decided to compare the Canon G7 X's dynamic range to two competing enthusiast compacts, the Sony RX100 III and the Panasonic LX100 (though some will likely argue the LX100 is a bit too big to be a direct competitor). You can always compare to other models on DxOMark.com.

As you can see from the above graph (click for a larger image), all three cameras have similar dynamic range when normalized. The G7 X's maximum dynamic range is 12.7 EV at base ISO, with a minimum of 6.5 EV at the top ISO. Interestingly, the Canon actually bests the Sony slightly at low to moderate ISOs, but they perform almost identically at higher ISOs, except at 6400 where the Sony does a bit better. The Panasonic does a little better except at base ISO, where it scores about 12.5 EV. As mentioned, though, the normalized dynamic range is so similar between these three cameras that for most purposes they can be considered equal, though at the pixel level (on screen), the LX100 does noticeably better with about a 3/4 EV advantage thanks to its larger pixels.

Click here to visit the DxOMark page for the Canon G7 X for more of their test results and additional comparisons.

  1 fc
11 lux
1/16 fc
0.67 lux
1/16 fc
No NR
ISO
125

0.5s, f1.8

8s, f1.8

8s, f1.8
ISO
3200

1/50s, f1.8

0.3s, f1.8

0.3s, f1.8
ISO
12800

1/202s, f1.8

1/13s, f1.8

1/13s, f1.8

Low Light. The Canon PowerShot G7 X performed very well in our low-light tests thanks to its fast lens, capturing bright images at the lowest light level (1/16 foot-candle), even at the lowest sensitivity setting (ISO 125). As expected for a 1"-type sensor, luma noise is a little high at ISO 3200, but fairly fine-grained, while chroma noise is well controlled. The G7X's highest ISO of 12,800 is quite grainy with strong blurring, but that's no surprise.

Color balance is pretty good with Canon G7 X's Auto white balance setting, just a touch cool, even at highest ISO and lowest light level. We didn't notice any significant issues with hot pixels, pattern noise or heat blooming.

The camera's AF system was able to focus unassisted to below the 1/16 foot-candle light level in our tests, which is excellent, and the G7 X was able to focus in complete darkness with the aid of its AF assist lamp.

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.

Output Quality

Print Quality
High-resolution prints up to 20 x 30 inches at ISO 125-200; Good 11 x 14 inch prints at ISO 1600; and acceptable 4 x 6 inch prints are possible up to ISO 6400.

ISO 125 images are able to produce pleasing, vibrant prints up to 20 x 30 inches. There's lots of fine detail upon close inspection at this print size and any larger would be pushing the limits of the sensor's resolution, but we'd certainly be happy to take it up a notch for 24 x 36 inch prints for wall display in this case.

ISO 200 prints look extremely similar to base ISO prints, and we're calling it here at 20 x 30 inches as well. Examining the prints very closely, there's ever-so-slightly less very fine detail in some areas compared to ISO 125, but not nearly enough to cause a drop in print size.

ISO 400 images print up to 16 x 20 inches with no problem. There's a slight reduction in fine detail compared to a similar-sized print at the previous ISO level, but visible noise is very well controlled and colors also remain vibrant.

ISO 800 prints look great up to 13 x 19 inches. We see a subtle increase in visible noise at this ISO and a further reduction in very fine detail, but contrast, colors and overall detail still look very nice and pleasing. Troublesome areas, such as many of our fabric swatches, begin to display a notable decline in detail, though.

ISO 1600 images have become noticeably softer overall, though prints still look good up to 11 x 14 inches.

ISO 3200 shots still display enough detail and low enough noise for pleasing 8 x 10 inch prints.

ISO 6400 images have become quite soft and lacking in fine detail, though there's enough detail as well as pleasing colors and contrast for a usable 4 x 6 inch print. A 5 x 7 inch print may be usable, though, for less critical applications.

ISO 12,800 is overall too soft and lacking in detail for us to comfortably consider any size a usable print. However, for less critical applications, we'd be okay with a 4 x 6 inch print.

With a larger 1-inch-type sensor, the Canon G7X does a solid job in the print quality department, especially a lower ISOs, with nice, large 20 x 30 inch prints at both base ISO and 200. In the middle ISO range, images become softer in detail, though visible noise is still well-controlled. Prints as large as 13 x 19 and 11 x 14 are acceptable at ISO 800 and 1600, respectively. At the extreme end of the ISO scale, prints become very soft due to noise and NR processing, with 4 x 6 inch prints topping out at ISO 6400.

 

The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Canon PowerShot G7 X Photo Gallery .

Not sure which camera to buy? Let your eyes be the ultimate judge! Visit our Comparometer(tm) to compare images from the Canon PowerShot G7 X with those from other cameras you may be considering. The proof is in the pictures, so let your own eyes decide which you like best!



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