Unwrapping the Mystery of Image File Types
There is an ongoing debate amongst many photographers. What’s the preferred file type, RAW, DNG, TIFF, or JPEG? The truth is, if you break the process down into four areas, each one of these files has a valid, useful purpose.
1) Capture Mode:
Shooting in RAW allows a photographer to capture more detail than if they were to shoot in JPEG. The RAW capture format also provides photographers with more control over the image in the digital darkroom. The ability to change the white balance on a RAW file can make an immediate impact on the overall look of the photo. For instance, by choosing a white balance setting of cloudy, or shady, your photo will take on a warmer tone.
If your indoor pictures have a yellow color cast, simply select the Tungsten White Balance preset. Since RAW files do capture so much detail, they will take up more space on your memory card, and hard drive. For example, a 10 megapixel camera with a 4GB Compact Flash card can hold about 135 RAW files in comparison to 420 JPEG/FINE images. If you decide to shoot RAW, you will want to pick up a few extra memory cards. If you would prefer to shoot in JPEG, be sure to have it set to the highest quality setting.
2) For Archival Purposes:
The DNG format was recently created by Adobe in an effort to unify the various RAW formats created by different camera manufacturers. For example, Canon’s RAW files are known as .CRW, and Nikon’s are .NEF. Many photographers feel this can potentially become problematic in the long term. They argued that their RAW files may not be future proof in newer software applications. Programs like Adobe Lightroom have an option to backup your RAW files as .DNG. If you want to protect your digital negatives (RAW files) for many years to come, DNG is well worth the effort.
3) For Making Prints:
For those special images that you want to print and display, the preferred file format is TIFF. By saving your completed image as a TIFF, you are using a lossless file which is capable of producing high quality enlargements. JPEG is a compressed file which can degrade image quality slightly. While this may not be noticeable on the computer screen, it will likely show on large prints. By starting with a RAW file, and converting to a TIFF, you are not compressing the file, or losing data. For prints, TIFFS should be saved at 300DPI.
4) For Email and Web Posting:
JPEG is the recommended format for sharing images on the web, or by email. The key is to optimize the file so that it looks best on a number of different monitors including desktop computers, laptops and tablets. If possible, choose a “Save for the Web” option, and resize the photo to about 1500 pixels on the long end.
Then, set the resolution to 72 dpi (dots per inch). This is standard for web viewing as opposed to 300 dpi for prints. Finally, make sure the actual file size is no larger than 300-400 kilobytes (kb). By doing this, you are ensuring that the images will load fast on your blog or website, and that they will be able to opened by recipients in email.