What is RAW? (part 1)

A Beginning Note

Some people tend to get into a religious war when it comes to subject of shooting RAW vs. JPG. The truth is that there are advantages and disadvantages to either approach. This aricle is simply meant to outline some of the differences. Not all digital cameras can capture RAW files – most pocket cameras cannot. Many people who shoot RAW with their digital SLRs also shoot JPG with pocket cameras, and are perfectly content to do so.

A Few Words About JPG

Before we get too far into the subject of RAW, let’s talk briefly about JPG photos.

JPG is the most widely used format for capturing and storing digital photos. It rose to prominence largely because, in the early days of digital photography when memory cards had small capacities and were fairly expensive, it allowed for photos to be stored in a compressed format (allowing more photos to be stored on a card) while still maintaining a reasonable degree of image quality.

JPG uses a type of compression known as lossy compression. That means that it “throws out” information in the photograph that it doesn’t think you’ll miss, in order to end up with a smaller file size. It’s similar to MP3 or iTunes files in the audio world. MP3 (as well AAC) is a lossy audio format – it throws out the parts of the audio that it thinks you won’t notice in order to keep the file size smaller. It’s called “lossy compression” because, once you create the JPG or MP3 file, you can never go back to the full uncompressed quaility – that information is gone forever.

With both JPG and MP3, you can control the amount of compression when you make or save a file. That’s why in most cameras you can select the quality of the JPGs – settings like “Standard”, “Fine”, and “Superfine”, or “SQ” (standard quality), “HQ” (high quality), and “SHQ” (super high quality). Higher quality settings result in higher quality (less compressed) images, but at larger files sizes. Lower quality settings keep the file sizes down (so you can store more photos on your card), but at a lower image quality. Too much compression makes the picture look blocky, and makes similar-colored areas like walls and sky look “splotchy”.

Since memory cards have become larger and comparatively inexpensive, it’s a good idea to use the highest quality settings when shooting JPG.

RAW vs. JPG

Here’s what happens when you press the shutter button to capture a JPG file:

  1. The shutter opens for the specified time and the camera’s sensor collects the light.
  2. The camera uses a “special recipe” to take the information from the sensor and turn it into an image. This special recipe affects things like rendering color, image contrast, color saturation, etc.
  3. The camera applies the white balance settings (either “Auto” or a WB setting you’ve chosen).
  4. The camera compresses the image according to the quality (compression) settings you’ve set up.
  5. The camera applies any other special settings you’ve set up in the menu (vivid color, more or less shapening, etc.)
  6. The camera writes the JPG file to the memory card.

By contrast, here’s what happens when you press the shutter button to capture a RAW file:

  1. The shutter opens for the specified time and the camera’s sensor collects the light.
  2. The camera takes this raw sensor information, makes a note of the white balance setting (but doesn’t apply it), and saves this information to a RAW file on the memory card.

That’s it!

When shooting RAW, you “develop” the raw image data into a photograph on your computer.

You may be asking yourself, “But isn’t that more work than shooting JPG?” And the answer is “Yes – sometimes”. In reality, a RAW workflow doesn’t have to be any more time consuming than a JPG workflow. That’s because most RAW development programs allow you to download photos from the card, batch rename, preview, straighten, crop, make image adjustments, reduce noise, and save to JPG all within one program. In most cases, the only time you need to open Photoshop or a similar editor is if you want to work with layers and/or specialized plugins.

In Part 2 of this article, we’ll talk about two key areas in which RAW can offer an advantage over JPG when it comes to editing your photos.


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