The Compact Camera Quandary
– State of the Market, Mid-2007

Image quality issues

File formats: RAW and JPEG

Nikon 7600 JPEG

Fig. 9: Crop from Nikon 7600 JPEG

Pentax DS Raw

Fig. 10: Crop from Pentax DS Raw

Fig. 9 and Fig. 10 are both about 20% crops from the unedited frames from their respective cameras shown at 100% pixels. The colours in Fig. 10 are far more accurate and subtle.

Fig. 9 was the best picture I could get out of that camera in bright daylight, given its almost complete lack of exposure controls. It would take extensive editing just to correct the white balance, not to mention the 2/3 stop over-exposure and the maxed-out saturation.

Fig. 10 was converted in LightRoom 1.1 using all defaults.

If you're reading this, I certainly don't have to convince you of the advantages of shooting RAW over JPEG and, for that matter, vice-versa.

RAW on a compact camera, however, is a bit problematic. Thanks to the infinite megapixel race, compact cameras are now generating ridiculously large files, yet have much slower processing engines than dSLRs, and consequently take much longer to record a given 10 mb or 20 mb file than a dSLR does. This moves the frame rate from so many frames per second to so many seconds per frame.

A less obvious issue is that the image quality of even RAW mode shots from a compact camera is not up there with that of any decent dSLR, even at base ISO. Much of this surely has to do with the lower signal-to-noise ratio of the tiny sensors and is most easily seen at extreme enlargements:

JPEGs have many issues, including in-camera sharpening, in-camera white balance (never correct), in-camera contrast curve, fixed colour space, compression artifacts, fixed bit-depth, and inability to support highlight recovery (combined with a camera that makes nailing the exposure an exercise in frustration).

At least Adobe LightRoom has come along to allow us to work with JPEGs in the RAW conversion environment.

White balance and colour accuracy

This could really be considered a sub-topic of RAW vs. JPEG. I've yet to try a camera that even comes close to nailing WB on even the majority of shots, while taking a white card shot to nail a custom WB in each new light is not only a pain but also impossible in many circumstances. There's nothing like a raw converter to overcome this issue.

Yet once you've got the WB correct, you're still not home free. The only thing you can count on when it comes to intrinsic colour accuracy is that every digital camera model will have its problems. It's no big deal to shoot a Macbeth Color Checker card then create and save a set of hue-by-hue corrections in a program like Adobe Camera Raw or LightRoom. Do that once per camera and kiss those wildly over-saturated reds goodbye. (Yes: you can still do that for a JPEG-only cam by using Photoshop's HSL dialogue, but then you have to remember to apply the correction to each image file from then on.)

Resolution and detail vs. latitude and DR

Pixel count was the make/break factor for so long, most of us are only now beginning to realize that the war is over. When I can look at the newspaper adds and see that I can buy a 6 mp compact camera for $129.99, I know it's time to move on to other things.

The current reality is very simple: for a given sensor size, the greater the megapixel count, the more noise. The more noise, the worse the ISO and DR situation. As explained on the first page, to achieve the same low noise, latitude, and high ISO handling that we see from a 6 mp dSLR in a 1/2.5" or 1/1.8" sensor the pixel count should not exceed 1 mp. Anything more than that and we're trading in low noise, latitude, and high ISO to gain resolution. This is why 50 is the base ISO of small cameras and why they struggle with 200 ISO, let alone anything higher.

Noise, artifacts and aberrations

We've spent a lot of time on the fact that noise is the bane of the small sensor; but the flip side of that recording is noise reduction and smearing. Just one of the many downsides of JPEG-only output is that the degree and quality of NR is no longer in your hands.

Two other downsides of JPEG are being limited to 8-bit colour and having even that defaced by compression artifacts that become more apparent the more up-sampling you apply.

Lens aberrations are just a fact of life. When choosing a compact camera we're choosing the sole lens we can use with it (barring attachments). Whatever barrel distortion, pincushioning, and chromatic aberrations it possesses are what we'll be stuck with.