In this popular tutorial on using the raw format, we’ve told what you need to know before shooting raw files, explained what a raw file actually does for your images, how to convert raw files and what edits to make (and when) in Adobe Camera Raw. It’s a pretty exhaustive list, but we’re not done! This week we tackle the subject of how to save a raw file.
When I come to save my converted raw images, my photo-editing software offers lots of file formats, such as JPEG or TIFF, along with 8-bit or 16-bit. Which is the best format for saving raw files?
The best format for saving your converted raw files depends on what you want to do with the images.
TIFF files can be saved over and over again without any loss in quality, whereas each time you re-save a JPEG image some file information will be lost, degrading the quality.
This is fine if you are doing all of your adjustments in raw, and just need a file to view, print or send.
However, if you want to make further adjustments in the main Photoshop interface, and want the best quality possible, TIFF is best.
When saving a TIFF file you have the option of 8- or 16-bit, and there is much more tonal information in a 16-bit file.
But this isn’t compatible with all of the adjustments and features in many types of software.
You can make use of this extra information if you are using Photoshop CS5, but if you are using Photoshop Elements to edit your images, 8-bit TIFF is the better option, because this application doesn’t have many editing options for 16-bit files.
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If I save my raw file as a JPEG, isn’t it the same as just shooting JPEG in the first place?
If you are simply opening the raw files in Adobe Camera Raw, applying the default adjustments and saving as a JPEG, then yes they are going to be very similar to JPEG files straight from the camera.
But this is missing the point of a raw file, which is to fine-tune the settings for each image.
In difficult lighting conditions, the JPEG from a converted raw file can have less noise, better highlight and shadow detail and a more accurate white balance than a JPEG image straight from the camera.
I’ve noticed that when I’ve edited my raw files in ACR, another file appears alongside it in the folder with a .xmp suffix. What is this?
When working with most raw formats (apart from DNG), ACR doesn’t permanently alter the original raw file when you make adjustments, so it needs another way of storing the information.
These .xmp files are ACR’s way of saving the information so that next time you open the raw file in ACR it will still have all of your adjustments applied.
These are known as ‘sidecar’ files, and will normally be saved automatically when you click Open Image or Done in the ACR window.
The only time that you need to worry about these extra files is when you are moving or copying the image from one place to another, when backing-up your images onto another hard drive or if you want to edit them on another computer.
If you only copy or move the main raw file you will lose any adjustments you have made, so next time you open it in ACR or Photoshop Lightroom it will revert back to the unedited, default settings.
If you want to keep your adjustments you need to make sure that you copy both files (or copy the whole folder), or move and copy files within Adobe Bridge or Organiser, which will copy these sidecar files automatically.
These files only apply to raw files edited in Adobe software, as like raw files themselves, each software manufacturer has its own standard for storing the information.
What is non-destructive editing, exactly?
When you save a JPEG or single-layer TIFF image after editing, all the data from the original file is discarded and re-written.
So once you have closed the image all of the original data is lost. When you edit a raw file the new settings are stored alongside the original data.
These settings can be inside the file, or stored in a separate file, which is used by the editing software to remember your last settings.
Some programs, such as Photoshop Lightroom, offer a similar option for JPEG and TIFF files, storing the editing information along with the original file so that you can revert back to the un-edited image at any time.
This is true as long as you don’t overwrite the original file with a new one when you finally develop or export the images from Lightroom.