“Whatever you do, do it in RAW!”
This motto is true in photography, and even more so in astrophotography. But why is it so? Is there really no place for JPEG in astrophotography? Are RAW images hassle-free?
Let’s find out in this article.
What Does RAW Mean
Loosely speaking, a RAW image is the digital equivalent of a film negative. In reality, a RAW file is not an image that can be visualized with classic software, but must be developed before using RAW editors such as Adobe Camera Raw.
Aside from the unprocessed signal from the camera sensor, A RAW file also contains a number of complementary information that is embedded, but not applied to the image.
Some of the most common data embedded in the RAW file are: the type of lens used and its lens correction parameters, the “in camera” white balance, picture style, etc.
While those settings are not affecting the RAW data, some of them may be applied to the JPEG preview embedded in the RAW file.
Say you set your camera to shoot in black and white: the RAW image is still in color, but it’s preview is black and white.
What Does JPEG Mean
The JPEG image format is arguably the most common standard format for digital images, and the name stands for “Joint Photographic Expert Group”.
The format uses a lossy and compressed image data to create an image file that is both lightweight and readily usable with any software and device able to visualize graphics.
Despite the lossy compression, a JPEG image can still retain good quality, but every time you save a JPEG, the compression is applied and the image quality is reduced.
Until not long ago, the JPEG format was the standard for compact cameras and camera phones, while the RAW format was reserved for prosumer DSLR cameras.
Shooting in RAW Vs JPEG: What Changes For You?
The difference between RAW and JPEG data is not limited to how the data are saved in the digital file, but shooting and editing for a format or the other are also different.
Digital cameras and smartphones are small computers with logic boards and processors at their hearts, with software able to manipulate the images before they are saved on the memory card or inside the device.
There are many settings and filters you can apply in-camera nowadays:
- Apply White Balance
- Apply Noise Reduction
- Apply Sharpening
- Apply a picture style (night scene, B&W, vivid, …)
- Panorama Stitching
- Auto HDR
- And more …
When you shoot in JPEG, the image is processed, these settings are applied and the image is compressed accordingly to the chosen quality (medium, fine, extra-fine) before being saved.
On the other hand, when you shoot in RAW, those camera settings are ignored for the most part and are not applied to the RAW data.
The only notable exception is long exposure noise reduction: this option will cause the camera to automatically take a second photo right after the one you took, using the same exposure, ISO, and aperture settings, but without opening the shutter.
This “dark frame” is then subtracted to the original image to remove hot pixels and reduce thermal noise.
No other noise reduction, sharpening, or style setting is applied to the RAW.
To summarise, here is what you should consider to decide whether to shoot in JPEG or in RAW:
- You want a readily visible image: shoot JPEG.
- You want to share your image on the fly: shoot JPEG.
- You want to directly apply filters and effects to the image: shoot JPEG.
- You want to create a panorama: shoot JPEG.
- You want to have full control over editing your image: shoot RAW.
- Light conditions are very difficult, and want to recover as many details as possible: shoot RAW.
In mixed situations, you can always shoot RAW+JPEG: you will need a larger memory card, but you can get the best of the two worlds.
RAW Format: What Pros And Cons?
Let’s quickly discuss the Pros and Cons of using the RAW format.
The biggest pro in using the RAW format is that you are in full control over the image development process.
A RAW image has a bit depth of 12 or 14-bit, which is much higher than the usual 8-bit used for JPEG: this means the RAW data can not only retain more colors but also data in a larger dynamic range than JPEG images.
This makes the RAW suitable for shooting in difficult light conditions with large dynamic range, and it is possible to recover a lot of detail during the editing, particularly in overexposed parts.
With RAW, you can carefully color grade your image with ease as in-camera white balance is not applied to the image: you can choose and tweak it during editing easily and effectively.
Having a 12 or 14 bit-depth and being uncompressed, means a RAW file is heavier (has a larger size) than a JPEG one.
For my Sony RX10, a bridge camera with 20 megapixel sensor, a RAW weighs about 21MB, while the in-camera JPEG is about 5MB.
I admit that with the drop in price of the SD cards, it is not a problem to have a memory card of 128GB or more, so the fact that RAW files are larger than JPEG is not a real problem.
A more real nuisance is the fact that RAW images are not readily available for sharing and view.
What you see as a preview is only the embedded JPEG, which is indeed affected by your camera settings. If you shoot in RAW, you cannot avoid editing.
That could be as fast as pressing “auto” in Adobe Camera Raw, Adobe Lightroom & Co., or be a lengthy process: either way, you have to develop the image.
JPEG Format: What Pros And Cons?
What are the pros and cons of using the JPEG format?
There are several Pros of using the JPEG format:
- Images are readily visible on a huge number of devices, from computer to smartphone, tablets, etc.
- Images can be shared directly from the camera or smartphone.
- Images can be printed directly off the memory card, or smartphone.
- Image quality is often good enough for small prints and screens, despite the compression.
- Images take up less space on your memory card or hard drive.
- JPEG optimization software, such as JPEG Mini, can further compress the file with negligible impact on the image quality.
- Images are often of good quality right off the camera, and may not need further editing, particularly for “snapshots”.
There are a number of Cons to consider though:
- Images are affected by camera settings such as noise reduction, sharpening, and white balance: once the image is taken is pretty much game over.
- The “small“8-bit depth makes editing of JPEG images more limited than with RAW (or TIFFs). It will be hard to recover a good amount of details from dark and bright areas of the image.
- Every time you save a JPEG, you lose image quality due to the lossy compression.
- Because of the compression and both depth, a JPEG can show a big amount of posterization in the sky or other areas with uniform colors.
- You may not be able to change the style of the image afterwards: if you shoot B&W you will not be able to get a color image out of it.
RAW Or JPEG: Which One Is Better For Astrophotography?
Now that you know what the Pros and Cons are for the two formats, which one is better for astrophotography?
I like to say that in astrophotography, there is not such a thing as getting it right in camera. From this alone, it should be clear that RAW format is the winner when it comes to astrophotography.
Astrophotography is all about recovering details and the faint signal of your target, while reducing digital noise through a series of well established pre- and post-processing steps.
Shooting in RAW will make all these usual steps in the astrophotography editing workflow much easier and successful, for a better image quality.
Things such as image calibration, image stacking, histogram stretching, star calibration, and color grading can’t be properly done with JPEG images.
For this reason, if you are using astrophotography software that does not accept RAW files, like StarStax and Starry Landscape Stacker, you should convert your RAW files as 16-bit TIFF files, rather than JPEG.
An Application For JPEG Files
Having said so, there is a place for JPEG images in astrophotography: Star Trails.
When you do a star trail you are recording the movement of the stars across the sky, often over a landscape.
A barely decent star trail, particularly if you are using a wide-angle lens, records the star movements for at least 30 minutes, and this is done with a number of relatively short exposures.
Good star trails can involve photographing the sky for several hours, during which you may collect hundreds of images.
If you can get the white balance right and a neutral style for the images, by using the JPEG format you can save a lot of space on your SD card and a lot of time in front of your computer.
But remember to take some photos of the landscape in RAW, as only the star trails will be taken from the JPEG images, while to edit the foreground is better to work with the RAW data.
RAW Files And Adobe Software: The Automatic Lens Correction Conundrum
Are you using a micro four-thirds camera and electronic lens or a bridge camera? Stay clean from Adobe Camera RAW and Adobe Lightroom.
Or, better say, convert your RAW in 16-bit TIFF using Mac OS Preview, Raw Therapee, Affinity photo, or any other RAW converter that does not apply the lens correction parameter. Then you can use the TIFFs in Adobe products.
Say you want to do a star trail: this basically means to blend all the images together in “lighten mode”.
But if you use an electronic lens for a micro four-thirds camera or a bridge, Adobe Camera RAW (ACR) and Adobe Lightroom automatically apply the lens correction parameters.
You cannot disable this, and as a result, you will end up with a checkered pattern on your images.
And this even if you use a specific software such as StarStax with TIFF created converting the RAW files with ACR or Lightroom.
This is a known issue, yet Adobe as no made it possible for the user to choose not to apply the lens correction for MFT lenses and for Bridge and Compact cameras.
If you want to know if such correction is applied by default, in ACR, go to the module optics->profile and check if you have a message that a profile has been applied.
These parameters are embedded in the RAW data, but luckily, other RAW converters do not apply those settings by default, and the checkered pattern will not show itself in the final image.
Q&A: Common Questions On Image Formats
Can you convert RAW photos to JPEG?
Of course! You must do that, at some point, as the JPEG image is the one you will be able to print and share on social media, etc.
All editing software allows you to export the edited image in several different formats, including JPEG.
When you export your image in JPEG, you will likely resize it to a smaller size: to avoid a soft image, you can choose a resize algorithm that sharpens the image, or do that manually before resizing the image.
When saving the JPEG image, I personally prefer to do so using the maximum quality for the exported image: should I need to manipulate the JPEG directly, this should give me an edge.
Are Raw Files Sharper Than JPEG?
A common complaint about RAW files is that they look dull and softer than the JPEG.
This is true, but only because RAW images need to be carefully edited to show their true potential, otherwise you are looking at how the sensor captures the image.
On the other hand, JPEG images straight from the camera already undergo an editing process which often involves noise reduction and image sharpening.
As a result, JPEG looks far nicer than unedited (or poorly developed) RAW, but this is not a problem of the RAW format.
Which Programs Are The Best For Editing RAW Images?
There are a number of options available for editing RAW images.
We have classic photo editors such as:
Or you can use the software that comes from your camera manufacturer to edit the RAW or convert it to a DNG or 16-bit TIFF.
One advantage of doing this is that RAW files are proprietary formats: every manufacturer uses different file formats.
Plus, photo editors may apply by default some settings to the RAW to make it look good: we saw Adobe can apply by default a lens correction to the raw, but it also applies a certain amount of sharpening when a RAW file is loaded in ACR or Lightroom.
Arguably, the software from your camera manufacturer is the one that better knows how to read the RAW file and the best settings to apply to it.
So, different software may display the RAW image slightly differently: don’t be surprised.
Finally, there are batch converters and editors such as RAWTherapee. You can use to convert all of your raw with the same settings applied.
I personally like Adobe Lightroom for general photography: simple and intuitive, with a lot of features and, thanks to the Adobe subscription, should you need more you will also have Photoshop for free.
And Adobe Bridge, should you need to cull and grade your images before you begin editing them.
In this article we have discussed the difference between photographing in RAW and in JPEG and which one is better.
The answer is in what you photograph and what you want from your images. Are you just getting family snapshots to share with your family members? shoot in JPEG. Do you want to be able to get the best out of editing your images? Shoot in RAW.
Are you into astrophotography? RAW is the way to go.