JPEG file format: The what, the how and the why

JPEG explained in plain English

There are lots of acronyms in the photography world. And I am not a fan of them. But this is a universally used acronym, and an important one for us photographers to understand.

JPEG file format: The what, the how and the why. JPEG stands for Joint Photographic Experts Group. JPEG is a digital image file format, and a method of compressing files to make them smaller and also readable by anyone. JPEG files have an amount of processing applied at the time of image capture that cannot be removed.

What is important is JPEG files and their relevance for us photographers, and that is what I will explain here, along with telling you how I use the JPEG file format in all my photographic work.

Before I begin, what do I mean by a file format?

When I say file format I mean the type of file that is created by a digital camera when an image is taken. Cameras take photos in JPEG, and more sophisticated cameras also offer the option of a different format called RAW in addition to JPEG.

There are other formats, but I will stick to the two most common formats in this post.

So JPEG refers to the type of file that your digital camera produces, or to the file type that you save an edited image as that other people can look at. Don’t worry – I will explain.

What file formats are there other than JPEG?

The most common formats digital images are taken in are JPEG and RAW.

Do I need to know about JPEG?

It is important to know the difference between JPEG and RAW file formats. The selection of either the JPEG or RAW format before taking a digital photograph will have a direct impact on the data captured by the camera. This will impact on the processing and the finished image, and some of these things cannot be undone.

So yes, this is important.

What is the difference between JPEG and RAW files?

There is a fundamental point here. A JPEG file is compressed by the camera, with an amount of processing “baked in” to the file that cannot be undone.

A RAW file has no processing added by the camera, it is the bare RAW image capture with no processing applied at all.

This is the main difference.

When you are taking photos with a digital camera JPEG is one file format that you can use. RAW is an alternative file format that you can use to take photos with.

With my Canon 6D I can take photos in both JPEG and RAW at the same time, which I rarely do to be honest.

What is the actual difference between JEPG and RAW files?

A JEPG file looks much better than a RAW file, as there has been some processing done to the image on capture. A JPEG image looks more finished, because it is!

Here are two images taken using my Canon 6D using the RAW + JEPG camera setting. No further processing has been applied.

The RAW file taken with my Canon 6D

The RAW file taken with my Canon 6D

The JPEG file taken with my Canon 6D

The JPEG file taken with my Canon 6D

Photos courtesy of Paxos Travel Guide.

A JPEG file looks more like a finished image. Well it does when compared to a RAW file, which is dull, flat and lacking in colour, detail, vibrance sharpness and brightness.

Dull and flat basically!

Are JPEG and RAW file sizes different?

Yes. JPEG files are much smaller than RAW files. Taking the two photos above as an example, these are the respective file sizes of the two images after import unedited into my Lightroom Catalogue.

JPEG file – 8MB

RAW file – 25MB

I know that the JPEG file is still quite large but the image that you are seeing on the screen was compressed on export from Lightroom and is actually 222KBs.

What am I looking at on my cameras LCD screen?

On a DLSR/ mirrorless camera, if you are shooting in RAW, after you have taken a photo you are actually looking at a JPEG version of the RAW file on your LCD screen.

I know this sounds a bit bizarre but this is what actually happens.

Do I use RAW or JPEG?

I always shoot in RAW on my cameras. This is to maximise the amount of data in the image capture process, and also gives me the maximum flexibility when processing images in Lightroom and Photoshop.

This is the part of my workflow that is relevant to this post.

  1. Set my camera to RAW image capture only
  2. Take images in RAW format
  3. Import RAW files into Lightroom
  4. Process RAW files in Lightroom and Photoshop
  5. Export images in JPEG format out of Lightroom for client issue, sharing or publishing.

It is only when I need to send an image somewhere that I convert the RAW file to JPEG. Normally this is done to an image or set of images when I export them out of Lightroom.

This is a simple task to do using Lightroom. At the time of exporting the images I also compress the files, the amount depending on the intended use of the images.

Why do I not shoot in JPEG?

I process every commercial image using Lightroom and Photoshop. I do not want processing to be done by the camera at the time of image capture. I want to do all the processing myself. And I want to capture as much information as possible.

Are there other file formats apart from JPEG?

As well as JPEG and RAW there are various other file formats, including

  • PSD
  • Tiff
  • Dng
  • Gif
  • Pdf

What is a RAW file then?

If you want to to know any more about RAW files check out the post next week on my photography blog which will be about this and this only.

One thing to mention here though is that to be able to open and view a RAW file you need software such as Lightroom or Photoshop. JPEG files can be opened by any PC or device (I am sure there are exceptions to this but exceptions is what they are).

Who are the Joint Photographic Experts Group?

Well I am not aware of them other than in relation to the creation of the acronym JPEG. And to be honest that is not important here!

Are there any other formats of JPEG?

JPEG is JPEG. There are variations in the level of compression of JPEG files, but the file format itself is universal.

Can anyone read a JPEG file?

Pretty much anyone with a conventional PC, Mac, iPhone or Android device should be able to open a JPEG file and view it.

How do I create JPEG files?

Over simplifying things a bit, if your camera is set to record images in JPEG then you don’t need to do anything else. If however your camera is set to record images in RAW format you need to either change the format in your camera or convert to JPEG using software such as Lightroom or Photoshop.

You can shoot in JPEG and RAW at the same time on some cameras, giving you the best of both worlds, but duplicate files.

How do I compress a JPEG file?

There is lots of proprietary software for compressing JPEG files. I do this in Lightroom, where I can change the level of compression at the point at which I am exporting a RAW file out of Lightroom. I can also change the physical size of the image, depending on what I am going to be using it for.

Do I lose image quality when I compress a JPEG file?

Yes you do. It has been said that the optimum level of compression is 92%. At this rate of compression the loss of image quality is virtually impossible to see, and the file size reduction is significant.

If you compress a JPEG file once, and then compress the file again, you get further loss of image quality.

A word on non-destructive editing

The editing I do to RAW files in Lightroom is non-destructive. This means that anything that I have done to an image I can undo. Once I export an image out of Lightroom, converting it to a JEPG fie, the changes cannot be undone to the JPEG file.

The RAW file is always there in Lightroom though so don’t worry!


These are one and the same so no need to worry about these.

Further reading

If you found this post interesting check out another post on my blog titled 21 Reasons I Shoot in RAW but Share in JPEG which builds on the explanation in this post.


I hope that having read this post you are now comfortable with what a JPEG file is, and when you should use this particular file format.

To sum up, I shoot in RAW and export images out of Lightroom into JPEG. It really is that simple.

Rick McEvoy Photography – photographer, writer, website creator

#jpegfileformat #jpegexplained

Rick McEvoy

I am Rick McEvoy, an architectural and construction photographer living and working in the South of England. I create high quality architectural photography and construction photography imagery of the built environment for architects and commercial clients. I do not photograph weddings, families, small people or pets - anything that is alive, moves or might not do as I ask!! I am also the creator of the Photography Explained Podcast, available on all major podcast providers. I have a blog on my website where I write about my work and photography stuff. Rick McEvoy ABIPP, MCIOB

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