High ISO noise reduction
As we've mentioned in the noise section of this review at higher sensitivities the JPEG engine's application of noise reduction is a little heavy-handed, resulting in very clean images but a loss of fine low-contrast detail. If you like this approach is pretty much a question of personal taste but if you apply customized noise reduction in raw conversion you can squeeze some additional detail out of your images.
The sample image below was taken in low light at ISO 6400 and the Standard noise reduction setting. The image is very clean but some of the fine detail in fiberous cape has been lost. We converted the raw file in ACR 6.7 and applied some custom noise reduction (luminance 6, chroma 28, chroma detail 25) which results in a grainier but more detailed image. Some of the individual fibers in the cape are now visible and chroma noise is still very well controlled. On the downside there is more visible luminance 'grain' in the image.
This kind of experiment is of course only of relevance to you if you print very large sizes or view your images at a 100% magnification. Overall, the G1 X's high ISO performance is excellent, no matter if you use the out-of-camera JPEGs or prefer to play with the raw files.
As we've mentioned in the noise section of this review, when shooting raw+JPEG you have no control over the noise reduction in the JPEG file. The option is still visible in the menu but grayed out which is annoying for anyone who is used to shooting raw and JPEGs with custom parameters at the same time.
|JPEG - ISO 6400 / NR Standard||Raw conversion ACR 6.7 Beta|
|100% crop||100% crop|
Distortion and CA correction
Distortion Correction is applied to G1 X images by default and cannot be switched off. Most up-to-date raw conversion software will honor the camera's 'instructions' and apply distortion correction in the conversion process. To see what distortion in an image actually looks like at the point of capture we converted the image below in DCRaw which gives us the captured pixels without any corrections applied. Our sample image was taken at the 15mm wideangle end of the lens and as you can see the distortion at this lens setting is pretty extreme. Vignetting is also clearly visible in the corners.
When examining the out-of-camera JPEGs there is some softness in the corners of the images which is almost certainly a consequence of the correction process but overall the G1 X's distortion correction is doing an excellent job, eliminating a large portion of distortion with only a minimal loss of quality at the edge of the frame. It is worth stressing that we're presenting the 'original' image here purely as a point of interest - you will never see results like this under normal useage or file handling conditions.
Please note that we have desaturated the DCRaw sample below as colors weren't converted correctly.
|Out-of-camera JPEG with correction applied||DCRaw conversion - no correction applied|
Chromatic Aberrations and purple fringing are not much of an issue on the G1 X. These image imperfections are corrected automatically in the out-of-camera JPEGs but also aren't too intrusive in the uncorrected raw files. The purple fringing in the image below, which was taken at an equivalent focal length of 93mm, is pretty much the worst we could find among our several hundred sample shots. As you can see, in the JPEG image fringing is barely visible.
|Out-of-camera JPEG - 100% crop||Adobe ACR conversions - 100% crop|
Overall Image Quality/Specifics
In general the G1 X's images are very good and in terms of image quality they're pretty close to current Canon APS-C DSLRs, such as the EOS 7D and 60D, which use a sensor with a similar design. That said, in terms of image processing and image quality options the G1 X is a Powershot compact camera and not an EOS DSLR. This means the colors are pretty saturated and bright, the tone curve is quite contrasty, which can lead to abrupt clipping, and sharpening can be slightly unsubtle with some pixel-wise halos around high-contrast edges.
It also means low contrast shadow detail can be smeared a little by noise reduction but not too destructively. Nevertheless the rendition of fine detail at low sensitivities is very good and close to Canon's mid-level DSLRs. However, where the G1 X really shines is at high sensitivities. Canon's Digic 5 processor is doing an impressive job and the impact of noise and noise reduction really only becomes noticeable at ISO 1600 and above. Canon's JPEG engine prioritizes clean images over fine detail but nevertheless, due to the good quality of the captured raw data, the end results are excellent, with compared to the competition in its class, still very acceptable low-contrast detail, good saturation and very few noise reduction artifacts. At high ISOs the Canon G1 X delivers amongst the best image quality of all APS-C sensor cameras (despite the sensor being closer to Micro Four Thirds in size). That said, at least some of the G1 X's advantage in terms of high ISO image quality is being offset by the faster lenses of premium compact cameras such as the Olympus XZ-1 or Fujifilm X100.
Converting low ISO raw images won't give you a huge amount of additional detail but of course you get the usual post-capture control over a range of image parameter such as white balance, sharpness, contrast etc. The G1 X's default tone curve is a little steep which can lead to blown-out highlights in high contrast scenes. The ability to pull back some of the highlight tones in raw conversion can be very useful too. When converting high-ISO raw files you get the additional benefit of control over noise reduction. So if you'd want to trade some of the JPEG's 'cleanliness' for a little bit of extra low-contrast detail you can do so by applying a customized noise reduction recipe. The Canon's high-ISO raw files are very good in terms of noise and detail and offer a lot of flexibility for custom processing.
As we've seen on other Canon models before the white balance response to low tungsten light can be overly warm, but again this too can be corrected for in raw conversion.
Probably our biggest criticism of the G1 X in terms of image quality is the fact that you’re not allowed to change the JPEG processing when recording raw, so you cannot change noise reduction, dynamic range enhancement modes, color mode and other image parameters. This means you are stuck with the default processing if you want to shoot with the presumption of using the JPEGs, but with RAW files available to fix white balance and other settings in post processing when necessary. If you can live with this limitation though the G1 X delivers excellent image quality across the ISO range with very few nasty surprises waiting for users.