File Formats: RAW and Jpeg

File Formats

Most cameraphones, and most compacts, don’t give you a choice of file formats – just jpeg. Pretty much everyone is familiar with these – you’ll have seen them on the web, shared them on facebook and so on. Once you get onto more expensive compacts, and DSLRs, you’ll find RAW mode as well, and things can get confusing. RAW mode broadly means that the image file contains all the data from the sensor, with no loss of information. This obviously makes for a larger file, but also one of higher quality.

Great, you think, I’ll buy a decent size memory card, and shoot in RAW mode all the time, and, full disclosure, that’s what I do as a professional. There is a catch. A couple of catches actually. First off, RAW files can only be opened in certain programs – unlike jpgs which can just be spat straight out of the camera, onto your phone or tablet and away they go. RAW files need to be converted from RAW format into either jpgs, TIFFs, or other file formats which can be read by a wider range of software. Second, each camera has it’s own RAW format – not even each camera brand, but each model. This means you’ll have to stay up to date with software if you buy a new camera, or even wait a month or so after a new model is released before buying it so that the software people can update their tools.

RAW Conversion

On the plus side, this RAW conversion process allows you a bit of a safety net. The amount of control you have over a RAW file will vary with different software programs, but you should be able to do all sorts of things to the RAW file before you convert it to something else, such as fine tune the exposure, select a specific white balance, crop it a certain way, increase or decrease contrast – essentially most of what you’d expect to do in any modern image editing program you can do to a RAW file as part of the conversion step.

You’ll then have a finished file in whatever format you like, with all your work done to it, and here’s the bonus – you’ve not damaged the original file. Most software will remember what you did, so when you reload the image the settings you applied are still there, but the adjustments you’ve made are non-destructive – you’ve not harmed the RAW file in any way, and you can easily reset them all if you don’t like them, and start again.

Most RAW conversion software also allows you to copy and paste any adjustments you’ve made, and this can be a huge advantage. Let’s say you work on the first image in a sequence, but you decide you want to apply the same settings across the next dozen images, as you know they were all shot the same way. A few clicks, and across go all the settings, no need to work on the files individually.

There are several RAW conversion programs out there, some quite expensive, some free. I’ve used Capture One, Adobe Lightroom, and Adobe Camera RAW, and have spent by far the most time in Lightroom – it’s an essential part of my workflow. This isn’t the place to go into detail about software, but if you want to shoot in RAW and get the best quality from your camera, you need some conversion software, and the Adobe subscription package with Photoshop and Lightroom in costs less than £10 a month. I’m not on a kickback from Adobe, although I bloody should be!

File Formats – jpeg

So that’s RAW, but Jpegs are still perfectly OK quality, and usually much smaller file sizes, plus, as we know, they can be used and shared straight out of the camera. You may have the choice to shoot at different resolutions in jpeg (almost never in RAW, although it is becoming more common) and whilst this is a nice feature to have if you’re in a hurry and need to share some images immediately after the shoot without access to a computer, you may regret not having a high resolution image some time in the future.

The settings in a jpeg can be adjusted, but the difference to RAW files is that the image quality will start to degrade quite rapidly when you adjust a jpeg. This is because all jpegs have been compressed. You’re usually able to choose how much compression your camera applies to a jpeg, with less compression giving you better image quality, but a larger file size, and more compression giving you a tiny file, but much lower quality.

So your “quality” options with Jpeg are:

Minimum compression – maximum resolution (image size) – large file + high quality.

Maximum compression – minimum resolution (image size) – small file + low quality.

Jpeg Compression

Jpeg compression works by your camera or a computer examining each pixel of an image, and seeing how close it is to the pixels next to it. The more identical they are, the more information it discards – this is what’s called a “lossy” compression system – clever name! This makes file sizes nice and small, and when used carefully it can still produce images of very high quality. The problem comes when you apply a lot of compression. It usually shows up first in areas of what look like uniform tone, but aren’t, such as the sky. The computer looks at all that info, and rather than deciding it’s made up of several shades of blue, it just calls it “blue”, and you can end up with what’s called “banding”, you can see why it’s called that from this image:

File Formats - Jpeg banding from high compression

Here’s a quick recap of the differences between the 2 file formats:

RAW – better quality, larger file size, can only be opened by certain software, needs converting to jpeg or other format for sharing, but lots of changes can be made during conversion without damaging the original RAW file.

JPEG – still OK quality, smaller file size, can be used straight out of the camera, settings “baked in” and changing them can degrade image quality, near universal acceptance of format across devices and software.

My general advice would be, always shoot with the most quality and resolution you can, and as little compression as possible. We talked about memory cards earlier, and there’s really no reason not to buy one of a decent size, and stop worrying about how big your image files are. You’re far better off having resolution and quality you don’t need than struggling to find some, and having to correct your images until they fall apart. To begin with, use jpeg, as you don’t want yet another technical thing to confuse you by having to do RAW conversions to. Then, if your camera will let you, shoot in RAW+jpeg, as that way you’ve always got a jpeg to fall back, or you can share quickly, plus a full resolution, high quality RAW too.

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