This article originally appeared in Outdoors Unlimited, the publication of the Outdoor Writers Association of America.
©Michael Furtman, 2005. Revised, 2015. No reproduction without permission. 



The Real Truth About JPEG images  

by Michael Furtman

As one of the first working professional photographers to transition to digital photography, I ran into a lot of head wind. Some editors simply didn't want to deal with digital images (or know how). They lost their jobs. Another issue was file format. It is one of the great myths in digital imaging – initially adopted as gospel by both photographers and editors alike – that JPEG images are so inferior to RAW as to make these images unsuitable for professional work. JPEG is different from RAW, that's for sure, and both have their advantages, but to consider JPEG files unsuitable for professional work was simply wrong. And time has proven me correct.

First, some terms: RAW files are compressed files, but are “lossless” – that is, they lose no information in compression. Generally speaking, a RAW file will be three to four times larger than the same image shot in JPEG, not in dimensions, but in megabytes. For instance, if the RAW file was 24 mb, the JPEG version would be stored by the camera at around 8 mb.   

The myth of JPEG unsuitability arises because a JPEG image is a compressed image, and that in the process of compression, information is lost. It is also common belief that each time you open and close a JPEG file, it undergoes more compression, thus continuing to lose information. Let's take a look at these assertions one at a time.

While it is true that a JPEG file does lose some information in compression, the amount lost is so small that it is virtually indiscernible to the human eye. I've posted an image shot in RAW and JPEG simultaneously. You can evaluate for yourself how much difference there is, and whether or not those differences, if any, are significant. That comparison can be found HERE.

Part of my business involves selling art prints. I've sold some at ridiculously large size, and they've turned out beautifully, and all were shot as JPEGs. How big can you go with a JPEG? Believe it or not, a photo of a peregrine falcon in flight, taken years ago with a puny 6 megapixel dSLR and shot in JPEG, was purchased and ran as a wrap on a giant delivery truck for a publishing company. At the time I first wrote this article (2005) some publishers were still asking for RAW files. A decade later, I personally know of NO publisher that requests RAW images. In fact, every client I have (and I do this for a living, every single day of the year) requires images to be delivered as JPEGs. I’ve sold many JPEG images to publications that have run as a double-truck (two page spread) – and the editors had no qualms about the quality. So while theoretically, a RAW file is superior to a JPEG file most of the time, the question to ask is whether or not that extra information contained in the file is necessary for your intended results. In other words, if you can't see the difference in print, is shooting RAW really any advantage?

The question I ask you to ask of yourself is very important to this discussion. What are your intended uses for the image? If you are into making "photo art" with a huge amount of photo manipulation, then perhaps RAW is the way to go. If you crop images heavily, then you probably should shoot RAW. But neither is a common practice. Photographers looking to sell images (and for whom this article was intended) should know that they MUST COMPOSE THE SHOT IN CAMERA. Editors will NOT buy cropped images. And editors DON'T crop images, except to fit a space demand in the publication -- I can't ever recall, out of the thousands and thousands of images I've sold, one that was cropped by more than 15-20% by an editor.

Some claim that RAW is superior because it is your “digital negative.” Yes it is. But so is your original JPEG image. If you make any adjustments to a copy of it, and never re-save the original, you’ll always have an original to return to. To insure the best quality when shooting JPEG images, make sure you shoot at your camera’s highest JPEG settings, turn-off in-camera processing, and if possible, set the color space to aRGB (Adobe RGB) if your final output is going to be for print (off-set printing, or even desk-top printing), since aRGB has a broader gamut of colors, which are similar to those used (CMYK) in off-set printing. There are a couple in-camera settings you should avoid if shooting in JPEG mode. First, you can not "unsharpen" an overly sharpened image. Make sure your in-camera sharpening settings are low. You can always tweak the sharpening later in editing. Also, if you use your camera's "high ISO noise reduction" feature, you may regret it, because that too is irreversible. Better to leave that turned off, or to low, because you can reduce noise later in Photoshop or other editing programs.

There’s one last myth about JPEG – that it doesn’t provide enough adjustment latitude for correction for professional work. Bunk. A JPEG file will give you at LEAST one full F-stop above and below proper exposure for correction purposes. For our use as outdoor photographers whose work appears in magazines, JPEG is actually more forgiving than the slide film we shot for years, which has essentially zero latitude. I reader of this article recently emailed me and said that since I wrote the first version a decade ago, things have changed and now RAW files offer 6 full stops either way for exposure correction. While that is amazing, you'd have to be a damn poor photographer to even need 2 stops, let alone 6, and you'd have to be shooting in a completely manual mode to screw up that badly. I mean, there is that little rectangular thing on the back of your camera that sort of looks like a television screen -- you can actually review your image AT THE TIME YOU TAKE IT to see if your exposure is correct.

When should you use RAW? Well, you can use it all the time, if that's your preference. It is very useful -- maybe even necessary -- if you’re shooting a concert or sports event indoors under funky lighting, so you can correct the white balance later. In fact, being able to easily correct white balance is probably the biggest advantage of shooting RAW. And if you shoot just a handful of images a day, why not use RAW? You'll only have a few images to process, and you won't be clogging up hard drives, if that's all you shoot. I have friends who are landscape photographers who spend a day waiting for that moment when the light is just ideal, and shoot just a few frames. In that situation, of course shooting RAW makes sense. Finally, if you can't get within two stops of a proper exposure, by all means, shoot RAW. 

OK, so JPEG is fine, initially, but they’ll degrade over time, right, because each time you look at them and close them they get compressed again? No. It is NOT TRUE that opening and closing a JPEG file continues the loss. In fact, saving a JPEG image multiple times during a single Photoshop session introduces no addition compression.  

To be sure of this, I contacted the programmers of Adobe Photoshop. What I learned is that when you use “SAVE AS” (renaming the file causes Save As) or Save/Close at the end of an editing session (over-writing the original), does it undergo another compression, and then, so very little as to be undetectable provided you save at Photoshop’s maximum JPEG setting of 12. Opening, examining, and then closing the file has absolutely no impact upon it, nor does using the SAVE option multiple times during a single editing session.  So....when you SAVE, then close it (which also means you're over-writing the original, which I don't recommend so that you can return to it in the future) or SAVE AS (you edit the original, then give it a new name, requiring SAVE AS) does it undergo compression, but in both cases, it only goes through ONE MORE COMPRESSION. That's not enough to alter the image quality in any discernible way. Not at least to the human eye, or for the purpose of print.

To test this, I took an image and saved it 30 times during a single session – a number far greater than anyone would normally ever do. I then produced 100% crops of the two images and placed them side by side. I then emailed this composite image to several magazine photo editors, asking for their opinion and they all said the same thing – they could discern no loss of detail, or increased JPEG artifacts. To view this image yourself, click HERE.

I also tried “SAVE AS” multiple times. By the fifteenth time, image degradation was apparent. But judicial use of this method of saving (one or two times) results in no discernible loss.

One of my acquaintances who is a professional photographers' technical contact at Canon summed up the differences between RAW and JPEG in a useful, understandable manner for those of us who remember the days of film. He suggested that photographers consider RAW to be the digital equivalent of print film, and JPEG to be the digital equivalent of transparency (slide) film. Print film has always allowed for great latitude in processing than slide film. I think this analogy is a good one. Magazine photographers have always shot slide film. We know how to get a decent exposure -- something even easier now with digital since you can look at the image in the review monitor, or examine the histogram, while on location. If the image is poorly exposed, you know it immediately, and can make the adjustments needed to get the subject right. There really is no reason to come away with a poorly exposed image these days.

Being a smaller file size, JPEG is better for action photography because your camera will not have to pause to write to disk as soon, and you’ll also get more shots per flash card, although each generation of cameras, with increased buffers, makes this less of a factor. But one thing doesn't chage -- if you shoot many images in a day, your work flow will be easier and much, much faster with JPEG because, as anyone who has worked with RAW files knows -- even if they love RAW files -- these files require much more post-processing, which can be a time consuming venture. Finally, JPEG files take far less space on your hard drives, which is no small consideration for those of us who do this for a living. Just think about it. I have four 3 terabyte hard drives storing my JPEG images. If those images were in RAW format, they'd be four times larger -- I'd have to have 16 3 terabyte hard drives to accomplish the same storage task. What a nightmare!

Remember, it is important that you preserve the integrity of your JPEG file. In addition to insuring that your retain the original file without over-writing it (make alterations to a copy), it is wise to turn off any in-camera processing, such as sharpening, contrast, and hue adjustments, or set them to low levels. Not only should you make these modifications in Photoshop, where you can do a more precise job, you want as "clean" a JPEG file as possible. Any processing done in-camera to a JPEG file can not be undone. Most dSLRs will allow you to turn off or modify in-camera processing, although some point-and-shoot digital cameras will not.  

There’s a time and place for RAW. It is a wonderful format for many photographers. That said, JPEG’s bad rap is undeserved, and it is time we disposed of the myths surrounding it.

RELATED INFORMATION AND ARTICLES

This original verions of this article generated a lot of discussion on a web-based photography forum. While some of the discussion was interesting, a great deal of it was nasty and often silly, comments written by people who misconstrued nearly every point I made.

Many of the comments insisted I said that a RAW file was the equal to JPEG. If you re-read the above article, you'll see that I never made such a comment. Nor did I advise people to not shoot RAW. RAW is a great format, ideal for many people. JPEG, though, is also a great format ideal for many people, and that, of course, was the point of the article.

Some took umbrage that I had the gall to call your original JPEG, unaltered by post-camera processing, a "digital negative." In the context of the above article, it is called that simply because it is your unaltered original, one you can go back to start processing all over again should you wish, just like you can print, and print again, from an original film negative. 

Some insist that a RAW file is such a huge improvement over JPEG that the differences are "significant." Well, there are differences. Significant?

During the course of the online debate, I posted an image shot in RAW and JPEG simultaneously. You can evaluate for yourself how much difference there is, and whether or not those differences, if any, are significant. That comparison can be found HERE.

Finally, I wrote a little piece on what I think of "pixel peepers" -- people who look at a photo zoomed in at 100% or more. If it gets you mad, don't bother to write to me. If you like it, feel free to send me a note. 

Read "On Pixel-Peeping" HERE.

 

 

This article originally appeared in Outdoors Unlimited, the publication of the Outdoor Writers Association of America.
Copyright Michael Furtman, 2005. Revised, March 2015

 

 

 
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