Image Capture Options


Many advanced compact cameras support raw image capture, but few are optimized for it (see Chapter 7 for much more on raw image capture). All digital SLRs support raw, and many are capable of recording images in raw and JPEG at the same time. Which format is best?

Raw Capture

For pure image quality, you can't beat raw. The raw format is simply a recording of the light values as seen by each pixel when the image is captured on the camera sensor. There are no modifications made to the data, and it's stored in the full bit depth supported by the camera (typically 12 bits) for the maximum color information.

So why wouldn't you use raw? Well, although it gives you the best image quality, it also takes some extra effort on your part to achieve those results. You can't just take a raw file from your camera and print a photo. There is some pre-processing required first to render the unprocessed sensor data to a useable file format, such as a JPEG or TIFF, for editing, enhancement, and printing. If you're doing hundreds of photos for, let's say, a kid's soccer event, you very likely do not want to spend the time needed to process all these images. In cases like this, it makes more sense to shoot in JPEG, which, when accurately exposed in-camera, I consider to be "good enough" much of the time.

When you're ready to explore what the raw format has to offer, see Chapter 7, which goes into much more detail on raw formats and using the image-conversion software that it requires.

JPEG Settings

JPEG is the most useable file format around for photos. Every online photo lab, Wal-Mart, kiosk, and other photo-printing location supports JPEG photos directly. If your images are taken in JPEG, then you can take the memory card out of your camera, pop it into their machine, and it spits out all the photos you want with minimal fuss or effort.

So, why wouldn't you use JPEG? The biggest reason is image quality. When you shoot with JPEG, you start out by throwing away image information. dSLR cameras, in raw mode, are capable of recording in 12-bit (128 tonal values) color; that's 4,096 color values per pixel. Shooting in JPEG mode reduces that to 8-bit color (28 tonal values), or 256 color values per pixel. JPEG also compresses your images. In theory, this sounds great. After all, you can store more images on a memory card and print them at a nearby store. But in order to compress those images, additional information is thrown away, which reduces the quality of the image. So, it's a trade-off.

Finally, JPEG is a processed file. When you capture an image in your camera, it is first captured as a raw image, no matter which format you're shooting. But if you store them as JPEG, for every image the camera automatically takes the raw file, applies image settings such as white balance, saturation, sharpening, and compression, and then converts that to the JPEG format before storing it on the memory card. The biggest drawback to this process is the lack of control you have over the final product. When capturing in JPEG, you're trusting the camera to choose the right settings for optimizing the image. For example, if you have the incorrect white balance set on the camera, the image is processed with an inaccurate color shift and saved. With raw, you can set the white balance to any value since it is not saved as a separate image until the raw file is processed and saved into an editable format such as a JPEG, TIFF, or PSD file.

Note

If you do plan to shoot in JPEG, you have the option to select a quality level. I highly recommend that you use the highest quality level setting to retain as much information as possible. After all, you spent a good chunk of money to improve your photos, so why save them at anything less than the best possible quality?





The Digital SLR Guide(c) Beyond Point-and-Shoot Digital Photography
The Digital SLR Guide: Beyond Point-and-Shoot Digital Photography
ISBN: 0321492196
EAN: 2147483647
Year: N/A
Pages: 91
Authors: Jon Canfield

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