What kind of file should you ‘Save As’?

A white balance problem was easy to fix because I shoot RAW.

When you take pictures with your camera you may be able to choose the kind of file your camera saves the image as.  Once they’re on your computer you definitely have options in the ‘Save as’ category. Each file format has it’s up sides and sown sides. These formats are important to know about to keep your pictures looking their best.

Photos are huge. They have to be compressed to be practical and that’s just what these file formats do. There are two kinds of compression, Lossy and Lossless. With Lossy Compression some of the file’s information is thrown away making the file really small. Lossless Compression doesn’t throw away any file information but it can’t make files as small. Like I said there are up sides and down sides. Let’s look at some common image file formats and see what they are good for.

JPEG

JPEG is a Lossy Compression format. Some of the file info is thrown away in order to make the file a lot smaller. This happens the first time you save and every time after that.  Loss of file information ultimately means loss of file quality.  You can usually save as a JPEG once or twice without reducing image quality too much. Unfortunately I always forget how many times I’ve already saved a picture. If I need to keep going back to edit, the quality of the photo can start to degrade as I save over and over.

I took this lovely photo in the Galapagos with a Canon Vixia camcorder.  It’s been saved once as a high quality JPEG.»

I saved this same JPEG at a little lower quality ( Level 8 in Photoshop. You might do this if you wanted to save a smaller file.)  Oh, and I saved it 10 times. I wanted to see just how much image quality suffers from saving over and over.

Now take a closer look.

You can see some jaggedness in both versions because I’m zoomed in quite a bit. Ignore that.Compression artifacts» become obvious in the second version. Details are starting to turn into big boxes in the second picture. Thankfully I kept a not re-saved copy. It would be a shame to have a photo ruined just by saving it.

JPEGs are really useful if you know you’re only going to save as a JPEG one time and one time only. They are great for the web and they are widely recognized by browsers and devices. But if you want to revisit the file and save it again, there are better options.

TIFF

TIFF uses Lossless Compression. It doesn’t throw away file information, so there is no loss of image quality no matter how many times you save. And according to Wikipedia “TIFF remains widely accepted as a photograph file standard in the printing business.”  This may be because “TIFF can handle device-specific color spaces … defined by a particular set of printing press inks.” Unfortunately TIFF’s can be really big.  And it’s not a file type that’s widely accepted for web use. Most browsers don’t recognize it.

I use the TIFF file format to save and compress finished images that I might want to edit more later. To be honest, I don’t use it often.

RAW

RAW is Lossless and generally smaller than a TIFF, but you have to shoot in RAW to get a RAW file. You can’t save another format (like JPEG or TIFF) as a RAW file later. RAW files are like they sound…raw. They contain all the info from your camera’s sensor pretty much unprocessed. If you take a photo as a JPEG or TIFF the camera does some processing automatically. For instance it will lock in the white balance you choose.»

That’s great if you you don’t want to edit your photos at all.  But have you ever set your white balance and had the colors in your picture turn out too blue, or yellow?  You can get some jacked up pictures this way. Sometimes even auto white balance get’s it wrong. If you shoot in JPEG these files are pretty hard to correct. If you shoot in RAW you can choose the correct white balance after you take the picture! How cool is that? You can make other color adjustments, lens corrections, brightness and contrast correction and even sharpen your photos non destructively» with a RAW Processor.

This photo is too blue. Roll over the image to see the corrected version.

A RAW converter is needed to process RAW files and convert them into a format that your regular photo editor (ahem…GIMP) can read. Camera’s will often come with this software when you buy them, but I’ve heard that Nikon does not. Don’t worry if your camera didn’t come with this software though. GIMP and Photoshop both have their own RAW converters and GIMP’s is free!

I shoot all my photos in RAW and keep a RAW copy of all of them for back up. It’s like keeping the negatives just in case. Check your cameras documentation to see if you can soot RAW pictures.

PSD or XCF

PSD is Photoshop’s native format» , and XCF is GIMP’s.   These are the best formats to save as when you’re still working on an image.  Both will save layers and masks just the way you left them so you can pick up editing right where you left off. Nothing that I know of will save the history of what you’ve done though. After you’ve closed and reopened the picture you won’t be able to ‘undo’ edits from your last session. Make sure you’re at a good stopping place before you save and close.

Still working on the picture? Choose your image editors native format to save.

PNG and GIF

Both use Lossless Compression. This makes them good for computer generated images or images containing text.  JPEGS can have obvious artifacts around sharp transitions like straight lines and text. PNG and GIF don’t have this problem. One the most important difference between PNG and GIF is that PNG can contain much more color information than GIF.  These file types are big. File size could be as much as 10 times bigger than a JPEG if saved as a PNG or GIF.

If you’re saving a computer generated image or an image with text, PNG or GIF may be the way to go. But it’s much more practical to save photographs in a native format if you are still editing. Save as a JPEG when you’re done.

That’s it…well not really

These are by no means all of the file formats you could use but they are some of the most useful for photography. Check out Wikipedia’s entry on Image File Formats for a bunch of others. I used it as a guide to make sure I got my facts straight. It’s pretty interesting stuff.

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1. What kind of file should you 'Save As'?