Digital SLR vs. Point & Shoot: Number of Images and Image Compression

By Shane Schmidt, Technical Marketing Manager for Pexagon Technology, Inc.

Today’s digital cameras enable us to capture an increasing number of images by way of larger capacity storage cards and image compression. A paradigm shift exists in the number of images we take and the image compression we use, or in some cases the lack there of.

Point-and-shoot digital cameras have been the consumer favorite in the digital camera market for quite some time. This is mostly due to cost effective pricing, overall ease-of-use and the abundance of digital print kiosks and photo printers. We all know how convenient it is to whip out that point-and-shoot and start snapping shots of the kids playing in the sand or that super cool custom chopper. But what’s all the hubbub about Digital SLRs?

With the introduction of Canon’s EOS Digital Rebel and Nikon’s D70 for the 2003 holiday season, Digital SLRs (Digital Single Lens Reflex) began flying off of the shelves. So much so that digital camera retailers and online shops still can’t stock enough of them. These cameras have become so popular that it is not uncommon to hear stories of bartering just to get your hands on one.

If we look back a couple of years ago the market was very different. DSLRs were available, but were mostly used by professional event photographers. It was the introduction of affordable cameras like the Digital Rebel coupled with the consumer’s desire to take more high quality digital pictures that spawned the rise in Digital SLR sales.

The Number of Images

If you’re like me, you can’t take enough pictures. Maybe it’s knowing that you don’t have to pay for unwanted prints or maybe it’s the ability to do so much more with your images. What ever it is, digital camera users are taking more pictures than ever before.

DSLR camera usage is vastly different than that of a point-and-shoot. Most point-and-shoot models are portable and novel with their compact profile and cool colors, but still leave a lot to be desired in functionality and overall image quality.

There are probably 6 or more pictures taken of a subject in a DSLR application for every one taken by a point-and-shoot user. While point-and-shoot users often find themselves waiting on the camera to shoot the next shot, DSLR users are shooting in bursts of multiple images. The rapid shutter speed, fast write times and rapid shoot modes create this dynamic. The image to the left is an example of the Canon EOS Digital Rebel’s continuous shooting mode as seen on Canon’s website.

Sample Images © 2003 Peter Read Miller All Rights Reserved.

With the desire for higher quality images and faster cameras comes the need for higher capacity media. Take a Canon EOS Digital Rebel for example. With a 512MB CompactFlash card shooting in RAW mode, you are limited to approximately 64 images. Make that a 2GB media card and you have the ability to capture approximately 250 images. The DSLR camera user is embracing a professional-like philosophy of “taking a large number of pictures to get one good one,” making high capacity media a necessity.
Camera Model:
128MB CF
512MB CF
2GB Microdrive
Canon EOS Digital Rebel (RAW)
16 Images

64 Images
250 Images
Nikon D-70 (RAW)
25 Images
102 Images
400 Images

Image Compression

Let’s talk a little about image compression. Two commonly used image formats among digital camera users are JPEG and RAW. The JPEG image format is compressed and is considered to be a “lossy” format. This means that the image is modified by the camera’s parameters (white balance, contrast, sharpness, etc.) and then compressed using JPEG compression before being stored on the media card. Depending on the level of compression a certain amount of information is thrown out.

The JPEG image format can include different modes such as “Fine, “Normal” and “Basic”. These different modes utilize different compression either increasing or decreasing the file size respectively. At the end of the day the image is still compressed and a certain amount of information is lost. The amount of information lost and the file size depend on the mode. In general, even the JPEG file sizes of today’s DSLR warrant the need for high capacity media cards.

The RAW format generally does not use compression and yields larger file sizes. There are some instances where a camera manufacturer may compress the RAW data, but in most cases will use lossless compression. This means that although the data is compressed, when decompressed there is no file degradation due to the compression. Along with the RAW image data the camera will also write a header file which contains all of the cameras settings or metadata. The RAW image data is not altered by these settings, but is tagged with this information. In essence, RAW mode captures the RAW image data and leaves it in its purest state for external processing.

It is becoming more and more common for digital camera users to shoot in RAW rather than JPEG. With high capacity digital media reaching 4GB and beyond and becoming more affordable, professionals, hobbyists and novices alike can all shoot high quality images in masses. Although it depends on the application and your equipment, my advice is to shoot RAW, become familiar with your camera’s image processing and/or editing software and purchase a high capacity media card to get the most out of your DLSR. For those of you who wish to keep the ease of use and convenience of a point-and-shoot, shoot in the highest quality mode and leverage a high capacity media card for added storage. Happy shooting!


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