What does JPEG actually do? (in camera)

I watched this video recently about a subject that frequently crops up in Photography on the nature of JPEG compression, and just how much compression should be applied, and what resolution you should use (in camera) if you’re a JPEG-shooter.

Even though the video was a bit turgid in places, it got me to thinking about what a JPEG image looks like coming out of my camera against the RAW image I process. I watched it right to the end which showed some sticking power. I’ll give you what I interpreted as the main points of interest.

Pixels are more important than the Quality slider when saving a JPEG for the best image. So save with loads of Pixels – original number if possible, don’t drop the resolution therefore – and use a lower quality setting to reduce image size if that’s an issue for the card in your camera. Then in post-production, as suggested in what I consider (imho) to be the best written expose of JPEG and Lightroom by Friedl, when you drop below 72-80% quality (compression) there’s not much decrease in image size, and very little drop-off in visual presentation.

I’m fortunate to have two card slots in the Sony A7r MkIII and have set it up so that a JPEG image is sent to the second slot. This image is configurable by Quality (ie resolution – X-Fine, Fine, Standard) and Size (ie relating to the amount of compression applied – high 42m, medium 18m and small 11m). I thought it might be interesting to see what the images looked like when taken in a challenging lighting situation that required ISO 4000 to get a shot at 1/60@f4 on a 24mm lens. I thought I’d look at the RAW image as well to see how “superior” it was!!!

Well that was interesting. Out of the camera all the JPEG images were sharper and that really puzzled me. Why? It took me a short while to realise that I’d forgotten the reason why I shot in RAW in the first place. Duh! RAW just captures what the camera sees. It doesn’t apply any corrections. It just sees the image and records it. Phew! I realised I had to look at Noise Reduction and Sharpening to get the RAW image close to what the JPEG was giving me, but I have to admit the JPEG taken at Xtra-Fine and High gave a very good image straight out of the camera (that’s the one on the right above), and if I didn’t want to do any post-processing, I’d have been happy with it.

[Note the shot on the left is the unprocessed RAW image saved with no compression; the one in the centre is the processed RAW image at 80% quality (compression)]

Some statistics for the JPEG shots:

Size of image from camera Original Resolution Cropped Resolution Saved at 80% compression Saved at 100% (no) compression
XF-H 23.4MB 7952×5304 2137×2137 946KB 2.8MB
XF-S 7.3MB 3984×2656 1070×1070 365KB 886KB
Std-H 7.6MB 7952×7952 2102×2102 901KB 2.4MB
Std-S 2.7MB 3984×2656 1088×1088 384KB 824KB

XF = Xtra-Fine (high resolution)
Std = “standard” resolution
H = High File Size (ie little compression to reduce file size)
S = Small (ie considerable compression to reduce file size)

I cropped all the images including the RAW image (originally 85.8Mb in size) to a square to get a comparable image at each resolution. For the RAW image this was 2126×2126 – comparable with the XF-L and Std-L JPEG images. I then saved the images at 80% Quality and 100% Quality (ie no compression) in Lightroom. For the RAW file this gave figures of 4.9Mb for the 100% Quality, and 1.5Mb for the 80% Quality. So you end up getting a JPEG from a RAW file (at this resolution) that is not greatly different from the JPEG taken from the camera.

How did I get the RAW to outperform the JPEG? I had to look at a number of sliders in Lightroom. Starting with Noise Reduction and then moving on to using Texture to arrive at an image that I liked. So the question is … is it worth using JPEG to just capture the moment. The answer is most definitely YES. I’ve always said that, and this piece of empirical research suggests that JPEG in the Sony camera is very good at noise reduction and sharpening. You may lose the colour information and the tones are not represented quite as well; but in this poor lighting situation where the ISO is very high (ISO 4000) the quality of the JPEG image is very good. So, armed with this information I just need to make a decision on how I set the camera up. Do I want to save a JPEG image as a backup to the RAW, in which case I need to set it to XF-H (in my notation), or for taking the card out of the camera to share on social media, in which case I would probably set the camera to record the JPEG shot as a Std-S image.

These are some of the test shots taken whilst I had my feet up! You can download the originals from the [Download] link under the photo if you want to more closely examine them.

The uncropped Std-S JPEG image saved at 100% [Download]

The cropped JPEG image saved from Lr at 100% reducing the file size to 2.8Mb; a loss of detail, but generally excellent noise reduction. [Download]

The cropped RAW image, grain and noise present because of high ISO [Download]

The finished RAW image at 80% Quality, after Noise Reduction – luminance and sharpening applied, as well as a bit of Texture added. Image size now 1.7Mb reduced from 6.4Mb cropped image. [Download]

So a final conclusion … if you’re a JPEG-man, I guess you should do the minimum amount of compression in camera, and you should shoot at the highest possible resolution. Then in post-processing you can safely save your JPEG at a reasonably high-rate of compression (lower quality setting) whilst keeping the resolution as high as you can. Does that rather obvious statement make sense?

Photography, technology and workflow – a further update

In an earlier post (in 2012) I detailed how I went about integrating my photography with the technology I use for post-processing and publishing. In what is a fast moving world everything is in need of constant review and revision

I use three cameras. The main one is the Sony Alpha 700 – it uses Compact Flash cards but I usually transfer pictures off it using the USB cable because my MacBook Pro and Windows 7 machines are set up for SD cards. The everyday camera (used on walks as well) is now a Sony NEX-6 – it uses SD cards, but again I tend to use the cable to transfer pictures. I use it also for short video clips. It’s worth noting that I have several Compact Flash and SD cards. I try NOT to delete any pictures  from a card (apart from obvious rejects) until I’ve uploaded the images into Lightroom. Finally I use my iPhone 4s for both pictures and video clips using the Capture app, although I have had difficulties with it as described previously in this post.

Incidentally, the iPad with the Camera Connector kit also works reasonably well and is a good travelling companion with the two cameras. I intend to experiment with the mobile version of Lightroom on the iPad as soon as I have the time … but I’ll leave that for another post.

If you read the earlier post you’ll see reference to using iCloud to synchronise images between systems. Not any longer. I found that “managing iCloud” and iTunes synchronisation was just something I didn’t want to engage with. At that time, I’d also switched-off Google+ Instant Upload (now Auto Backup) for Photos on the iPhone/iPad – did I really want a double dose of synchronisation? I wasn’t using Dropbox to synchronise either.

So … you’ll gather I changed my mind. This occurred principally because I changed my thoughts on how I was going to use Lightroom. I moved to a strategy of storing all my images, together with the main Lightroom catalogue, on an external USB disk. That meant the external hard disk became a hub for my photography. As long as images got uploaded to the disk and added to this catalogue, all would be well and synchronisation was unnecessary. I backup the catalogue when closing Lightroom, and the images at the time of uploading them into Lightroom. [With a secondary periodic backup of the external hard disk to satisfy my paranoia.] I move between the MacBook Pro and the WinPC and the move is seemless.

And as for the iPhone photos? Well I created an IFTTT (If This Then That) recipe to move images from my iPhone Camera Roll to a Folder called Camera Roll on my Google Drive. I also Enabled Google Drive as a source for Photos when posting from Google+. With that in place, after possibly some editing in Snapseed or Camera+, the act of  saving to my iPhone Camera Roll, added the image to the Camera Roll folder on my Google Drive. I could then import the image into Lightroom from that Google Drive folder, as well as have the capability of posting directly to Google+ (the only social media platform I use) from my desktop browser.

So nearly all my images are imported into Adobe Photoshop Lightroom (v.4.4) being placed in a Folder for the Year, within a Sub-folder for the import-date, residing on the external USB disk with a Backup Copy of the imported pictures being made at the same time automatically to a folder on a different drive either on the MacBook Pro, or the WinPC. The import is controlled by a Pre-set in Lightroom which I change every year to reflect the change in year folder. The backup folders are cleared-out periodically after other scheduled backups have taken place.

After processing images in Lightroom, which includes tagging them and adding them to Collections they can be exported  as JPEGs to Picasaweb or to the Google Drive folder as a Hard Disk export – for sharing in Google+, or to 500px, or Flickr (all using Lightroom Plugins).

Iris at RHS Harlow Carr

Why the image of an iris? Couldn’t think of anything more different from what I’ve been writing about 🙂