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How Many Pixels?

A reasoned approach to digicam specifications
(And a minor rant by Dave in defense of the "happy snapper.")

Why this article?
As we write this article, much of the digital camera world is breathlessly awaiting the imminent arrival of the 2 megapixel ("2MP" hereafter) digital cameras: Those having more than 2,000,000 pixels on their CCD sensors. In the newsgroups and discussion forums, and in our own email correspondence, these new devices appear to be assuming the significance of the Holy Grail to digital photography: Many, many photographers appear to be holding off on their purchases, wanting to get the very latest technology, convinced that the only cameras they should be considering are those with 2MP or more in their sensors.

This is certainly understandable, given the rapid pace at which the whole digital camera marketplace is evolving: Today's hot technology is next week's bargain-bin throwaway, or at least so it's seemed over the course of the last year. With technology moving so fast, it certainly makes sense to buy only the very latest, in order to get the maximum return on your investment... Or does it?

While our early tests with the Nikon CoolPix 950 and Olympus C-2000 Zoom certainly suggest that the 2MP digital cameras hold great things in store for the digital photography community, we feel that many people are being caught up by a whirl of specmanship, fueled by the manufacturers continual search for an "edge" to propel their sales ahead of their competitors. In the process, we think many excellent bargains in the marketplace are being overlooked, to the consumers' detriment. Hence this article, intended to focus attention more clearly on various reasons for buying a new digicam, and to help bring some perspective to the issue of resolution.

It's not just about resolution
There are many reasons to choose one digital camera over another, only one of which is the resolution and level of detail each is capable of capturing. This may seem obvious, but as we'll see, it's important to separate-out the various factors influencing your purchase.

Besides resolution, you should be looking at other image-quality aspects, such as color rendition, noise, and tonal range. To an even greater extent, you need to look at other features and factors that will affect your use of the camera: Do you want lots of control over the picture-taking process, or would you prefer the camera to attend to details of exposure, shutter speed, etc? How big a factor is the physical size of the camera? (A big, bulky camera that gets left in a drawer at home may not be as suitable as a more compact one with fewer features, but that goes everywhere with you.) Then of course, there are all the other issues, such as the software bundle that accompanies the camera, how it connects to your computer system to transfer images, etc.

High-end, "Creative Control" may be a valid reason to wait
One characteristic that's prominent in some of the latest offerings is the dramatic increase in the level of photographic control offered by the new 2MP designs: Both the Olympus C-2000 Zoom and Nikon CoolPix 950 offer significantly greater control over the picture-taking process than their predecessors, including features such as shutter- and aperture-priority metering, and extended ISO (light sensitivity) capabilities. But then, so do at least some other recent, non-2MP entries in the market, notably the Canon PowerShot Pro70, and the Sony D700, with 1.7 and 1.3 megapixel sensors, respectively. Overall, we're seeing a general trend for digital cameras to provide greater levels of creative control than has previously been the case. As noted though, there are products already on the market that offer some of this, and not all users need or want this level of sophistication

Take note of that last comment: Not everybody wants or needs the level of control offered by some of the newer camera models. Snobbish photo buffs look down their collective noses at the "happy snapper" who's content to let the camera handle the exposure and shutter speed, but nobody need feel any shame at including themselves in this category: Getting decent-looking pictures without spending a lot of time fiddling with knobs, menus, and buttons is an entirely valid photographic objective! If that's your primary interest, then why should you spend hundreds of dollars more for a camera model sporting multiple exposure modes and menu options that you'll never use? Some may argue that it's limiting to buy a camera without manual control options, but the fact is, I personally know many people who derive great pleasure from their picture-taking, yet have very little idea of the effect of different lens apertures and shutter speeds on the images they capture. More power to them! If they're enjoying their hobby, then far be it from me to insist that they "really ought" to learn more about basic exposure principles, to expand their creative options!

Cramming in a few more pixels may not be...
- A reason to wait, that is. Here's the big secret: 2 million pixels really isn't such a huge step beyond 1.5 or even 1.3 million pixels! Think about it: At the upper end of the sub-2MP cameras on the market, we have devices with image sizes of 1536x1024. Relative to the 1600x1200 image size of most forthcoming 2MP designs, that's only 64 pixels less horizontally, and 166 pixels vertically! Clearly, this isn't much of a difference! Even at the common 1.3 MP size of 1280x960, the difference is less than you might expect.

The proof is in the pictures:
See for yourself: Here are some sanity-inducing sample images, courtesy of the Imaging Resource. We could argue the theoretical merits of this issue all day, but in the case of digital cameras, a picture is really worth a lot more than a thousand words. To that end, we've prepared a set of sample images that our readers may find instructive in evaluating the differences between the new 2MP designs and previous generations of digicams

What we wanted to do here was to eliminate the variables of optical design, color quality, and other non-resolution issues that will exist between different digital cameras. In order to focus solely on the pixel-count issue, we've prepared some sample images from high-resolution PhotoCD Pro scans of a 35mm slide.

The sample images below were created by down-sampling a high-resolution PhotoCD scan of a 35mm slide to four common digital camera resolution levels: 1600 x 1200 pixels, 1280 x 960 pixels, 1024 x 768 pixels, and 800 x 600 pixels. The resampling was performed in Photoshop, using bicubic spline interpolation. (No arguments allowed about the relative merits of bicubic splines vs. Mitchell interpolation, etc!) Since it's beastly hard to accurately judge relative resolution in images of different sizes, we then re-sampled all of the test images back UP to 1600 x 1200, to provide a consistent basis for comparison. We then took identical slices of each image, and arranged them in the table below. Take a look at these: How big a difference do you actually see between the slices from the 1600 x 1200 and 1280 x 960 images? Surprisingly little difference, isn't there?

 

A clip from a 1600x1200 image, typical of 2MP digicam resolution.

The same image, rendered at 1280x960, then resized back up to 1600x1200. Not much difference, is there?

At 1024x768, details start to get noticeably "soft"

At 800x600, this image clearly has less resolution than the 1600x1200 version.


Printing is Believing

Throughout this site, we encourage people to download our sample images, and output them on their own printers: This is the truest test of what an image will look like in your own environment. Here, we provide links to two different sets of images. On the top row of the table below, you'll find links to the images which were re-sampled back up to 1600x1200 pixels, from whatever resolution level they were originally reduced to. (These are the images from which the clips above were taken.) The second row of the table contains the "original" images at the resolutions listed above. (For instructions on printing these images at a consistent size for comparison purposes, see the "Choosing a Camera" article by Barbara Coultry.) We encourage you to download the images and print them out, to see the magnitude of differences you may (or may not) find between many current digicam models and the new 2MP designs.

Image samples, typical digital camera resolutions

Full 2MP,
1600x1200

(524k)

1280x960,
Resampled up to
1600x1200

(508k)

1024x768,
Resampled up to
1600x1200

(480k)

800x600,
Resampled up to
1600x1200

(452k)

Original
1280x960

(444k)

Original
1024x768
(304k)

Original
800x600,
(208k)

The Bottom Line
While the new 2MP digital camera models in many cases offer a host of new and exciting features (as well as marginally improved resolution), we're convinced that many buyers are missing some great bargains in the marketplace: Older digicam models have had a longer trip down the manufacturing learning curve, and are often available at drastically lower prices than the latest designs. By settling for a fairly minor reduction in maximum resolution, you could end up saving literally hundreds of dollars relative to the very latest 2MP camera designs!

For More Info:

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