Format for Master Image


Today’s Question: Regarding, RAW and TIFF, once I process a RAW file, what is the best format to save it that will preserve all of the info captured by shooting in RAW? Is it TIFF along with its three times larger file size? I can’t imagine that one should save to JPEG, which would defeat the advantages of shooting in RAW.

Tim’s Quick Answer: The best answer depends to some extent on which software you’re using to manage your photos. That said, if you’ll be saving a “master” image from a processed raw capture, I recommend saving in the TIFF file format. The Photoshop PSD is also a good choice for this purpose, while the JPEG format is a bad choice.

More Detail: If you are using Adobe Lightroom to manage your workflow, there’s no need to save a new “master” image based on your original raw capture, because you don’t actually need to save a new file. Lightroom employs a non-destructive workflow whereby the adjustments you apply are essentially just metadata updates that relate to a specific raw file. You only need to create a new file when you want a copy of the image for purposes of sharing, such as to post online or send to a service provider to be printed.

If, on the other hand, you’re using software such as Adobe Photoshop to optimize your photos, you’ll need to save the processed version in a specific file format. Perhaps the worst choice for saving this new “master” image would be the JPEG file format. That is because the JPEG file format always involves “lossy” compression that will reduce overall image quality and likely cause visible artifacts, the resulting image won’t be capable of preserving any layers you created in Photoshop, and the file can only be saved with an 8-bit per channel bit depth.

To maximize the image quality and amount of detail in a master image you save based on processing a raw capture, I recommend using the TIFF file format. You can save such a file without lossy compression, in the 16-bit per channel bit depth, and with layers from Photoshop included. Similarly, the Photoshop PSD file format works perfectly fine, though in many cases you can achieve a smaller file size using the TIFF file format.

It is true that the TIFF (or PSD) file will be approximately three times the file size of the original raw capture, depending on the number of layers, compression applied, and other factors. However, if you need to create a derivative copy of the original raw capture as a new “master” image, in my view that file size is well worth the storage requirements in order to ensure optimal image quality.