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The First Stage of Post-Processing

by Mike McNamee

Part 2: Michael Pilkington discusses post-production of the landscape image, concentrating on the inital adjustments.

In my last article I spoke of the need to post process your images. This time around I am going to look at some key techniques that you should really consider when post-processing. Post-processing is divided into two key stages. The first stage is the initial processing of the RAW file using Adobe Camera Raw or the Develop Module in Lightroom to apply generic actions to improve the exposure and lights and darks in the image. The second stage is solely achieved in Photoshop where we address individual components of the image. Adobe Camera Raw (ACR) comes as a plug-in for Photoshop and Lightroom. If you open a RAW file from Adobe Bridge it will automatically launch the ACR plug-in for you. The develop module of Lightroom is exactly the same in terms of functionality and capability as ACR but presented as an integrated module within the Lightroom package. It is fair to say that the interface is a little more user friendly and pretty!

There are a few key objectives that we want to address in the first stage of post-processing:

Get the correct white balance
Establish a good tonal range in the image
Make corrections for lens limitations
Perform some pre-sharpening of the RAW file


Essentially we are creating a good foundation for applying the postprocessing in stage two.

Getting the correct white balance
I have the white balance on my camera permanently set to cloudy. I do this for a few reasons. Firstly I want predictability and consistency across all the shots I take (in fact every setting on my camera is set to manual). Secondly, I find that the settings in the main do not render correctly anyway (especially for long exposures) and lastly it is so easy to adjust it in post-processing. The slider we are looking for is Temperature. There are pre-sets available in ACR/LR but as for the camera I don't find these very useful. They are worth clicking to get a sense of where you want to be and then adjust the slide manually for the look you are after - to the left to make it cooler and to the right to make it warmer.

This particular image was taken as a long exposure so shifted to the blue end of the spectrum. It is worth noting at this time that during this process you will be making a lot of judgements around tonality and colour so it is imperative that you have your monitor properly calibrated.

Setting the tonal range and exposure
Now comes the really interesting part. We have to set the tonal range for the image and manage the exposure at the same time. Firstly we set whites and blacks. Select the slide for the blacks and whilst holding down the ALT key, move the slider to the left. Initially the screen will go black, but as you move to the left, specific areas will be highlighted. Bring the slider back to the right until these disappear. Repeat the process for the white slider, but this time you will be moving it to the right. This particular image taken in Tuscany was against a very bright sky. Whilst the exposure is technically correct, by increasing the whites it seems overexposed so I have decided to bring it down by half a stop and move the highlights slider completely to the left to reduce the brightness of the sky and also bring out the cloud detail.

Lastly I have moved the shadow slider to the right to bring out some shadow detail in the rolling hills.

Correcting Lens Distortion and Chromatic Aberration
Every lens can suffer from distortion, in particular wide-angle lenses. ACR and Lightroom have the capability to dial in the lens you used for the image and make the necessary adjustments. There can be limitations on this. For example, I use the Nikon 24mm tilt and shift lens a lot. This lens does not appear in the list of lenses that ACR recognises. Secondly, it is possible with my Nikon D800E to download to the camera lens profiles and have this action performed in camera. So clearly you wouldn't want to repeat this in ACR or Lightroom. I do find the lens correction to be a bit exaggerated and make any corrections required in Photoshop using the Warp tool.

What is essential is to remove chromatic aberration. Where you have dark areas against light areas, for example trees or mountains against the sky, you will get some level of green or purple fringing. Simply checking the 'Remove Chromatic Aberration' gets rid of it. ACR does a great job at this. If, on the odd occasion, it isn't completely successful then you can manually adjust green and purple defringe sliders. Correcting this at this stage is important, as it will require an enormous amount of work to achieve in Photoshop.

Pre-Sharpening
It is a fundamental feature of sharpening that you cannot perfectly judge the effect without making the final size of print. This, however, is a counsel for perfection and, with experience, you can make an attempt based on previous efforts.

In best practice you 'pre-sharpen' your RAW image and follow this by 'output' sharpening. Digital cameras inherently create slightly soft images. The sharpening function in ACR is very adept at pre-sharpening RAW files. We will need to sharpen the fully processed file once we are finished with it in Photoshop, but then sharpening will be relative to the size and resolution of the output.

There are four sliders that we can adjust. Amount and radius affect the amount of sharpening; detail and masking are known as suppressioncontrols that constrain the effect of the two previous controls. Amount is akin to a volume control. How much sharpening do you want to apply? I find that between 50% and 100% is where we have the best effects (using a Nikon D800). You can go higher if you want, but be careful. One of the greatest sins of post-processing you see is over-sharpened files, and this is only pre-sharpening. We will do more later in Photoshop.

The radius filter is very important and determines the width of the halos generated around the edges in a photo. A small radius will pick out fine detail and a high radius will have the opposite effect. Generally I use 0.8 to 1.0. The radius setting is resolution dependent, a high-resolution file can accept a higher value than a low-resolution file. This is also true for subsequent, Photoshop sharpening where files for web use (for example) require the smallest radius setting available if over-sharpening is to be avoided.

Now the so-called suppression controls. The details slider suppresses the halo effect in your image. As you change this slider, keep the ALT key depressed. Again you will see a greyscale image. The lighter (also white) the representation, the more the effect the radius slider has. Set to zero, the whole image is affected. Typically I set the detail slider to between 50 and 60.

BELOW: Holding down the Alt key to 'highlight' the effect of Radius settings is a poor witness to what is going on. In the composite below Radius settings of zero, 0.8 px and 3 px are shown (bottom upwards). There is relatively little difference especially as values between 0.5 and 1.0 are optimum. This leads to the conclusion that the only way to really differentiate between settings is to make prints! The masking slider protects those areas with a flat tone from being sharpened. This would be useful and effective in a portrait for example where you didn't want the majority of the face to be sharpened. In this image I have set it to 10 as there are lots of small imperfections in the bonnet of this rusty old car. If everything were super sharpened it would look very gritty indeed. For a landscape image I tend to leave masking set to zero - ie everything is sharpened.

As with all controls, depressing the ALT key as you change the slider shows you the level of effect the slider will have. White has full effect and blacks no effect.

Solving the Sharpening Conundrum
Given our misgivings about judging sharpening levels, what is the printer/post-processor to do? At Epson Print Academy we have a suite of images sharpened for inkjet printing at full 20x16-inch size. A ring around made with an action in Photoshop sharpens at 12 levels of strength and the delegates are invited to judge the most pleasing level. A number of patterns have emerged from the 500+ delegates who have viewed the test prints.

Pairs of viewers rarely agree on the 'best' level between Amount 40/ Radius 0.5 and Amount 80/ Radius 1.0. In other words the optimum pre-sharpening lies somewhere between the two values.

We use the Pixel Genius method of sharpening which can have a High Pass layer opacity between 0% (no output sharpening) and 100% ('full strength' output sharpening). Delegates rarely stray above 67% opacity but usually do not agree between increments of 33% - in other words they could not decide between say 20% and 40% so there is little point in changing by increments of say 5%. The choices depend upon subject content and its detail frequency but usually lie between 33% and 67% opacity.

Architectural shots made with Nikon D800 produce a lot of confusion with delegates unable to differentiate between Amount 40/Radius 0.5 and Amount 150/Radius 1.5, the latter being towards the limits of pre-sharpening. In other words, for this type of image, the D800 can take more sharpening because of the inherently high resolution of the file (we look forward to working out what to do with the new Canon 50mp files!!).

Much of the above goes out of the window with images shot at 6400 ISO where noise is so great as to rapidly deteriorate image structure at quite low levels of sharpening.

While it is difficult to set out absolute values, we find that female portraits (especially with fine hair) require the least sharpening strength, followed by butterflies and then by low-detail frequency images such as the test 'microscope' shot.

None of the above is of great use to the printer poised to set their values so we include starting values for experimentation - they might well suffice for the majority of work without modification.

What to do with the D800?

The Nikon D700 has images 4,256 pixels wide but the D800 covers 7,360 pixels. In theory therefore if a scene value is 1.0 pixels Radius for a D700 then the D800 would require 1.73 pixels. However, the noise of the D800 should be proportionally more as it offers a smaller pixel area and this limits the amount of sharpening that you might apply to a D800 image! In trying to resolve this we made sharpening ring arounds at an even larger range of settings. The initial scoping trials showed that noise became obtrusive on the image for all pre-sharpening values of Amount 150 Radius 1.5 (ie the entire right-hand column). Additionally the 67% and 100% Opacity value for output sharpening at Amount 80/Radius 1.0 was slightly over-sharpened also. With this in mind we repeated the ring around using values of pre-sharpening of 40/0.5, 60/0.7 and 80/1.0 with the same output sharpening values. The optimum was then judged to lie in the zone indicated but we could not in all honesty differentiate between the five remaining value sets. Amid all this confusion we have only looked at two simple parameters and not even brought Clarity into the equation - if you are confused you are in good company! The message here is don't let anybody ever tell you that the optimum sharpening is 'values x-y-z', we doubt they have scoped things out sufficiently diligently to ever be able to make such a pronouncement. Faced with this confusion you are probably best to start at Amount 60/Radius 0.7 and about 40% opacity, proof out and work from there.

What not to do at this stage

There are many other options and features available to you in ACR and LR. Generally I choose not to use them but use equivalent functions in Photoshop. For example, cropping and straightening, spot removal and colour saturation. Many of these actions are destructive, that is to say they make permanent changes to your file. You cannot go back and undo these things later if you change your mind. In Photoshop we can invoke a number of techniques to perform non-destructive changes to our files.

So there we have it. We have set a good basis for the second stage of post processing (which I will cover in my next article). All in all this shouldn't take more than a few minutes per image. You can also select multiple images and apply the changes to them all at the same time before opening them in Photoshop. Simply select all the images and then hit Synchronise to bring the remaining images into line with the first (corrected) image.



Updated 27/04/2026 16:44:22 Last Modified: Monday, 27 April 2026