The purpose of this exercise it to demonstrate the processing advantages of RAW, but at the same time to put these advantages in perspective. Higher image quality from RAW is often over-praised.
In theory, JPEG compression can introduce artefacts, particularly if it later receives strong adjustments in post-processing. In practice, with what we will do in this exercise, there will be no noticeable loss of quality. Plan and shoot three images in three different lighting situations. One should be in daylight, one in artificial lighting, and one high dynamic range.
Open and process each pair of images, JPEG and RAW, in your usual image processing software. Depending on the software, you may be offered different choices. Basically though, the JPEG has already been processed, so that any adjustments you make are, strictly speaking, post-processing, while the RAW image is waiting for your choices of white balance, exposure (to some extent), and so on.
In each case, take whatever opportunities are offered by the RAW converter to make the best of the image, including, in the case of the high dynamic range image, recovery of highlights and/or shadows.
Finally compare the two version of each scene, paying special attention too:
- Dynamic range
- White Balance and colour
- Local adjustment of any kind (this is a relatively new feature being offered by the more advanced RAW converters)
What differences, if any, do you see between the RAW and JPEG?
This was quiet a difficult exercise to achieve as I am still trying to get my head around Dynamic range so it has taken me a little longer than usual to get my images.
My Nikon has the ability to shoot a RAW file with the extension .NEF plus a JPEG file; each are recorded on separate memory cards. My RAW capture is set to uncompressed with a bit depth of 14-bits and my JPEG capture is set to fine, with compression set at size priority.
Initially, I wanted to use the same location to get both my daylight and high dynamic range images, but as said, it was much harder than I thought to get these shots; so three separate locations have been used.
For my daylight image I have used a photograph taken of the funfair at our local seaside resort – Southend-on-Sea – as the sun was shinning brightly and there was lots of colour to be taken in. I have used my Nikon D800 with my Nikkor 28-300 mm telephoto lens. As the sky was so clear and bright, I have introduced a graduated filter to bring back a little life to the sky and darken the bright areas within the frame.
For both images I have conducted the following minor adjustments in Photoshop:
- Taken out water and dust spots
- Slightly cropped out unwanted information (this was very minor)
- Hue adjustment +7
- Saturation +5
- Lightness -2
I have done this on both photos so that I can compare the effects within the two different kinds of file format.
Comparing these two images side-by-side, I actually think that the JPEG file contains richer colours than the RAW file, especially in the sky, and the overall colour cast is slightly more vibrant in the compressed image file. Although the colours are better in the JPEG image, the detail in the shadow is more visible in the RAW file, which is evident if you look at the arcades in the background of the shot. The white balance in each shot, which was set to sunny in-camera, has produced a good colour cast and is true in each.
Were things do start to change is within the histogram as the one representing the RAW file is smoother than the JPEG graph, indicating that the colours are smoother and the tones more even across the range; this is due to the RAW file being captured in 14-bits and the JPEG being captured in only 8-bits – the RAW file has much more data to play with and processes.
You can see that both images are well exposed, although the JPEG histogram does highlight the areas in shadow, where the details have been lost.
Also, once I had played with the image in Photoshop, the changes I made created spikes in the JPEG graph, indicating that pixels are beginning to be lost to the post-processing I conducted.
Where the RAW file really comes into its own is when you zoom into the darkest areas of the frame, as here you can see that information has been contained, but in the JPEG file noise is beginning to show and detail is being lost and the shadows becoming fuzzy.
This loss stands true to the exercises we have conducted in the past and proves that although the RAW file may not look quiet as good as the JPEG image, the RAW file format has captured more data, the detail of which can be seen when digging deeper into the image.
High Dynamic Range
For my High Dynamic Range (or high contrast) image I have used a photograph of some flowers in the garden. Although it was a sunny day, I moved the potted plant into the shade, so that I could use the effect of dappled light to illuminate the scene – something taken from our previous exercise, and a lighting condition I really like to work with. Again, I have used my Nikon D800 with my Nikkor 28-300 mm telephoto lens.
As before, I have made only minor changes to both images in Photoshop:
- White Balance from daylight to daylight (RAW file only)
- Exposure +0.49
- Offset +0.0018
As the JPEG file opens directly into Photoshop, bypassing the RAW converter, I have only been able to change the White Balance of the RAW image. This has been changed from daylight to daylight – yes, I know this sounds strange, but when I changed the WB setting in the RAW converter there was a marked difference between the original image and the image where I chose the daylight setting again!
As seen in the previous exercise, when comparing these two images, there really is little difference between the two, although I think this time round the RAW file comes out on top. Overall, the RAW image is a little brighter and the detail of the petals and foliage more vivid in the frame. Things really seemed to open up when I changed the white balance. The background detail is present in both shots, but as we saw previously, detail in the shadows is more visible in the RAW file, which can be seen when looking beyond the plant.
Again, this all comes down the more colours and tones being available in the RAW date.
Again, the histograms of each shot are very similar, and as the image is on the dark side, it tends to the left of the graph. As seen previously, after processing the JPEG image, the histogram is beginning to comb, indicating the loss of data and therefore pixels within the frame.
This loss of data is further highlighted when you delve deeper into the image.
As you can see, both images have quiet a lot of detail still, but the JPEG file is showing lots of noise in the spins of the leaves and the pixels are becoming blocky over the RAW file, which although does show signs of noise is still quiet smooth and detailed. This again clarifies that by having more data in a 16-bit image file you will have more data to play with and the loss of image detail is less relevant than in smaller more compressed files.
Finally in this exercise I have included an image taken under artificial light. Here I have used a set of Russian Dolls, set against a yellow background and lit with quiet a strong, directional tungsten bulb. I was not able to get the white balance right for this shot, so doing something I have never tried before, I dialled in a manual Kelvin number of 3570° which seemed to make things look much more akin to the scene.
The only post-processing changes made to this image were to take out dust spots and watermarks showing within the frame.
Comparing the RAW image against the JPEG shot, I find it really difficult to decide which is the better image and I think the thing that does it for me this time round is the brightness of the yellow in the compressed JPEG photograph. The colours in the JPEG shot do look a little brighter and slightly more vivid, but it does lake clarity in the shadows case by the dolls as the edges of these are softer compared to the RAD image where the shapes of the shadows are more defined.
Once again, there is little difference between the histograms produced by each file, but as seems to be the trend, the JPEG graph shows detail to both edges, confirming that some detail in the brightest and darkest parts of the image have been lost.
When looking at the effects of noise in these shots, it is quiet evident in the shadows cast by the dolls and looking at the black base in these two shots, more detail has been contained in the RAW file than the JPEG files, as expected.
Such an interesting exercise to perform, and again, such an interesting set of results have been received.
It is quiet fascinating to see the knock on effect that post-processing has on our images, especially when you compare the different kinds of file formats we use for capturing images.
My camera captures JPEG images well, and if I get the settings right in camera, there is little or no need for post-processing, so using this file format to capture images makes for a faster turnaround when producing the end product.
Good quality JPEG shots work fine, unless you are looking to enlarge your work or need to produce images of absolute clarity, then RAW should be the definite choice to make as a RAW files attention to detail far out performs JPEG.