Category Archives: Post-Processing

Articles relating to image post-processing techniques

Overcoming the Challenge of Depth of Field in Macro Photography

As anyone who has experimented with macro photography will know, this style of photography, and more specifically the nature of the subjects and lenses used, makes achieving a suitable depth of field very challenging.

Some photographers may like to produce the style of image where only one small part of the image is in sharp focus, with the rest receding into a smooth, surreal blur.

This is well and good, but sometimes one simply wants all of the details in a macro image to be rendered in sharp focus.

Sufficient depth of field is quite difficult to achieve in macro photography for two main reasons.

Firstly, the subjects often shot are typically small, which means that one needs to get close to the subject, using a lens whose magnification is life-size (or greater); and secondly, a longer focal length is needed, especially if the subject is a critter which will run or fly away if a photographer gets too close.

Longer focal lengths and very short subject distances both reduce depth of field, and do so more dramatically when combined.

One counter-measure available is to stop the lens’s aperture down to a very narrow aperture.  This sounds good, but there is a hidden danger: diffraction.

When a lens’s aperture is stopped down to an extremely narrow aperture, light rays entering the lens at various oblique angles must bend dramatically to enter the narrow aperture, and then find their way towards the focal plane.

At very narrow apertures, diffraction causes a loss of fine detail in images, resulting in a softer appearance.  In macro photography, where fine detail is often the very subject the photographer wants to capture, diffraction is more problematic than it would be in other forms of photography, such as landscape photography.

So, with a combination of a long focal length, short subject distance and a practical limitation to how far down one can set the lens’s aperture without degrading the quality of the image, how does one gain more depth of field?

It is easier than one would think, and does not require any special software if you already have Adobe Photoshop.

The technique is called focus stacking, and it involves capturing multiple images of the subject shot multiple times with different focus distances, and digitally blending them.

Each image captured must be framed identically, but what differs is the field of focus.  After each image is captured, it is simply a matter of adjusting the lens’s focus ring by a small amount to render another part of the image in focus.

Perhaps there might be equipment available which can adjust the focus ring in precise increments, but I have never looked into it, in my experience of having produced three macro images using this technique, I have found that the adjustment of the focus ring can be done manually, and still produce excellent results.

At the capture phase, I recommend using a tripod so that precise framing can be achieved throughout the numerous images that will be captured.

Using the live view mode on the camera allows for a much better view of the lens’s plane of focus, and also reduces any potential bumps resulting from contact with the camera’s optical viewfinder.

I also recommend the use of a remote shutter release to further avoid needing to make any contact with the camera.

Some contact with the camera will be required, as without a device to rotate the lens’s focus ring, it will need to be touched.  For that reason, care must be taken so that the camera is not bumped out of alingment.

How many images need to be captured?  That depends on the subject, the subject distance, the lens’s focal length, and how much adjustment of the lens’s focus ring is required to capture a series of images in which the closest subject matter is in focus, right through to the furthest subject matter.

Yesterday I photographed the intricate details of a rose laden with water droplets, and rather than opting for the arty shallow depth of field prevalent in many macro images, I wanted rich details in sharp focus throughout the image.

For my macro photography, I use a Canon EF 180mm f/3.5L Macro USM lens, which is challenging to use at the best of times, but I also attached my Canon Extender EF 2x II, which doubles the focal length.

I was therefore shooting a relatively small subject at a focal length of 360mm, with not a great deal of distance between the lens and the subject.  The result is not much depth of field.

One might think that I would need to shoot a dozen or more images to capture the full field of focus, but in fact I needed only seven images.

To produce a focus-stacked composite image in Photoshop, the technique is as follows:

  1. After raw conversion, load all of the raw files into Photoshop.
  2. One at a time, and in sequential order (this is important), copy each image to the clipboard, and then paste it as a new layer into the first image.
  3. Rename the layers using a logical naming scheme (eg, IMG_0001, IMG_0002, etc.).
  4. In the layers pallette, select all of the layers.
  5. Click the Edit menu, and select ‘Auto-Align Layers’.
  6. Set the Projection set to ‘Auto’ and click OK.  Photoshop will align the layers.
  7. Click the Edit menu and select ‘Auto-Blend Layers’.
  8. Make sure that ‘Stack Images’ is selected, and click OK.

Depending on the bit depth, dimensions and number of images to be stacked, it could take a while for Photoshop to complete the focus stacking.

The result will be a stack of layers with layer masks on each.  Photoshop’s focus stacking algorithm selects the in-focus subject material in each image and masks out the out-of-focus areas such that the resulting image is sharp throughout.

The next step is to create a new layer for the composite of the stacked images.

From the top layer, press Cmnd-Alt-Shift-E on a Mac, or Ctrl-Alt-Shift-E on Windows.  This keyboard-only command will produce a new layer of all lower layers without discarding the layers.  This is not the same as the ‘flatten image’ command, which I never recommend.

Once the composite image has been captured as its own layer, proceed to apply any other post-processing as desired.

Now, let us look at my results from yesterday’s rose image.

Firstly, here is a montage of my seven source images, and the resulting composite image Photoshop produced using the automatic layer blending option.

Focus-Stacked Rose

Focus-Stacked Rose

As can be seen in the above screen capture, images 1 to 7 all have different planes of focus.  The composite image in the lower right shows the raw result from Photoshop’s focus stacking algorithm.

One caveat of which to be aware is that the technique results in a softening around the edges of the frame, so it will be necessary to marginally crop the image.  For that reason, I recommend composing so that no critical subject matter is positioned close to the edges of the frame, as it may be damaged by the ‘soft border’.

Now, here is the final image after I completed my post-processing, which included cloning distracting spots, detail enhancement using Calvin Hollywood’s ‘Freaky Detail’ technique, cloning out of distracting spots, and contrast and sharpening adjustments.



Hopefully this article has been helpful in illustrating how a macro photographer can overcome the challenge of very limited depth of field by carefully executing the capture of multiple frames of the same subject at different planes of focus, and using one of Photoshop’s in-built functions to digitally composite the in-focus subject matter in the multiple frames to produce a rich, detailed image with everything rendered in sharp focus.

Time for a Sea Change?

It is no secret to those who know me well, in a photographic sense, that my motivation for photography in general, and seascapes in particular, has been distinctly lacking for the past year or so.

Additionally, time has been lacking for a few years, and my ability to get out regularly for a shoot, even if the desire was there, has been somewhat diminished.  Time continues to present a challenge.

Yesterday I attended a Photoshop post-processing workshop run by one of my fellow members of the Focus seascape and landscape photography group, based on Flickr.  It has been a while since I have had much contact with the people in the group, and attending yesterday’s workshop gave me a sense of belonging again.

The group’s founder was also there, and both on this occasion and the last occasion we met, he encouraged me to get out with the guys for a shoot.  I think I should take him up on that, and make a return to seascaping.

Today I decided to process and publish an image from my last really good seascape session.  Hopefully mentally re-visiting that morning will give me a much-needed push to make a comeback.

I hope readers enjoy it.

Swishes and Swirls

Swishes and Swirls

Perhaps in the near future I will have some fresh (ie, recently captured) images.

I need to get my mojo back!

Re-visiting a Six-Year-Old Brisbane Cityscape

On a wet and cold Sunday, I decided to re-visit a six-year old image and process it quite differently.

Firstly, here is the result:

Brisbane City from Kangaroo Point

Brisbane City from Kangaroo Point

In this version, the distortion has been corrected, and the contrast is much less aggressive.

As a point of comparison, here is the original version:

Brisbane City from Kangaroo Point

Brisbane City from Kangaroo Point

Naturally the perspective correction resulted in the loss of some subject matter — notably a building on the right side which has been completely eliminated from the new version of the image.

If I were to shoot the same image again, I would ensure that I would keep the axis of the lens parallel to the ground to avoid introducing perspective distortion in the first place; but otherwise I am pleased with the new version of this image.

HDR Processing: A New and Effective Technique

It has been a while since I posted an article on post-processing, and having discovered a new, effective and pleasing technique just last month, now is a good time to discuss my learning and show my results.

Hopefully readers will find value in what I am about to present, both in words and images.

HDR (high dynamic range) processing has been a large part of my workflow since my initial foray into this technique in January of 2011.  The results I achieved with my first HDR image seriously impressed me, and I have been using HDR imaging techniques ever since.

I discovered that it is possible to achieve very photo-realistic results with a combination of careful capture and restrained HDR post-processing.  It was always my intention to produce photo-realistic results — ie, reproduce what the human eye can naturally see — rather than opting for more ‘artistic’ and less realistic results.

The software I use for HDR processing is HDRsoft’s Photomatix Pro, which is one of the more common and more popular HDR imaging packages available.

Photomatix Pro has unfortunately attracted some negative attention due to some of the very garish results it can produce.  Such is its pervasiveness that many over-processed, intensely-saturated, halo-laden, noisy, illustration-like images have been described as having the ‘Photomatix look’.

This look does not at all appeal to me, and with restraint and sensible choices, I have found that Photomatix Pro can produce very photo-realistic results; and in all of my HDR images since, I have aimed to produce such results, and avoid the over-processed look that so many before me and after me have either set out to achieve, or accidentally achieved through a lack of restraint and judgement.

I find HDR processing most effective for interior images (such as cathedrals) where the dynamic range is very broad; such environments have bright highlights from windows, and very dark shadows.  This range of light levels is too much for even the most expensive camera in the world to capture, so HDR processing is a very effective way to reproduce what you can see when you are standing inside such an environment.

While I use HDR processing almost exclusively for interior architecture images, I have also found it effective in landscape, cityscape, seascape and even still life and macro images.

My interest lies in achieveing a very photo-realistic result which shows what the human eye can see, but what the camera can never adequately capture.

To achieve this objective, I typically shoot between five and nine exposures, each a stop apart.  Once I have metered and determined the ‘correct’ exposure, I dial in up to four stops of over-exposure and work my way back to four stops of under-exposure.  This gives me nine images with which to work, capturing details from the deepest shadows and the brightest highlights.

My post-processing workflow is summarised as follows:

  1. convert the raw images;
  2. save high-quality JPGs;
  3. load the high-quality JPGs into Photomatix Pro;
  4. choose a realistic tone-mapping preset;
  5. load the HDR composite into Adobe Photoshop; and
  6. perform my usual Photoshop post-processing.

Astute readers might wonder why I choose to work from JPGs at the HDR processing phase.  In short, the raw converter in Photomatix Pro does a bad job (in my opinion and experience), and the high-quality JPGs produce a much nicer result.  See my earlier article HDR Generation: Raw or JPG? for a more detailed and visual explanation.

In choosing one of Photomatix Pro’s tone-mapping presets, I find that the ‘Natural’ preset produces the most realistic results, and 99% of the time, it just works well.  Of course, the nature of the subject and dynamic range can affect the ability of the preset to produce the desired results, but as a general rule, the ‘Natural’ preset works best.  I have dabbled with a few others, but most of the presets are garish and unrealistic, so I avoid them.

During a recent trip to England, whilst processing my images, I discovered a new way of producing photo-realistic results with extra ‘pop’.

Rather than using just one Photomatix Pro tone-mapping preset, I performed the HDR processing twice, using two different presets.  The first was the ‘Natural’ preset, and the second was either the ‘Enhanced’ preset or the ‘Creative’ preset.

In Photoshop, I then blended the two HDR composite images together, taking the best from each.

Now, the ‘Enhanced’ and ‘Creative’ presets can and do produce some very garish, unrealistic and unappealing results; but when one takes only the ‘good’ parts from the image, and blends them with the more subdued and realistic results of the ‘Natural’ preset, the resulting image has extra ‘pop’.

The best way to illustrate this is with two actual images. I will show:

  1. the results Photomatix produced using the ‘Natural’ preset;
  2. the results Photomatix produced using the ‘Enhanced’ or ‘Creative’ preset;
  3. the result of blending the two HDR composites; and
  4. the final result after the rest of my processing in Photoshop.

Let us first look at one of my images of Ely Cathedral.

The capture phase consisted of nine exposures, from -4EV to +4EV.

This is what Photomatix Pro produced, using the ‘Natural’ preset:

Ely Cathedral - HDR 'Natural' Preset

Ely Cathedral – HDR ‘Natural’ Preset

Now, this looks nice and realistic, and contains lots of rich details throughout, but to my eyes it is too bright and tonally flat.  Granted, at this stage the image has not been darkened or had contrast applied, but despite that, it summarily lacks the ambience and atmosphere that I saw with my own eyes when I was standing there.

I then processed the nine exposures in Photomatix Pro again, but this time I used the ‘Enhanced’ preset.  This was the result:

Ely Cathedral - HDR 'Enhanced' Preset

Ely Cathedral – HDR ‘Enhanced’ Preset

This version of the image has more ‘pop’, but it is bordering on the over-done side of HDR processing.  Like the first version, the image is flat, but that is normal for HDR composites, unless you tinker with contrast in Photomatix Pro, which I do not do.

I like the tonality of this image more than the first version.  There is a darker overall feel, which is reminiscent of the actual cathedral, and there is more contrast and tone in the architecture.  However, it looks ‘HDR-ish’ (particularly in the ceiling), and not as realistic as I would like.

If only I could take what I like from the first image, as well as take what I like from the second image.  The good news is that I could.  I decided to experiment by blending both of these HDR composite images into a new version.

This was the result of that experiment:

Ely Cathedral - HDR 'Natural' and 'Enhanced' Presets Blended

Ely Cathedral – HDR ‘Natural’ and ‘Enhanced’ Presets Blended

To achieve this result, I added the ‘Enhanced’ composite to the ‘Natural’ composite as a new layer, added an inverted (ie, black) layer mask to hide the ‘Enhanced’ version, and then using a soft white brush at 50% opacity, I brushed the richer ‘Enhanced’ version onto the woodwork and side walls, leaving the ceiling and stained glass windows untouched.

By brushing in the ‘Enhanced’ version at 50% opacity, I was able to infuse some of that more over-done look without actually over-doing it; the detail was there, but the HDR look was not.

Doing so gave me the extra tonality, darkness and detail enhancements I wanted in specific areas (especially the woodwork and the columns), but preserved the more realistic ceiling in the ‘Natural’ version.

In my workflow, the blending of the two HDR composite images was the very last step.  There was basic processing to be done first.

Here is the final image, after all processing was completed:

The Organ and the Nave of Ely Cathedral

The Organ and the Nave of Ely Cathedral

There was a fair bit of extra processing involved, most of it being standard practice for my HDR images.

The first step was to bring back the details and the colours in the stained glass windows in the distance.  To do so, I added one of the darker JPGs as a separate layer, added a black layer mask, carefully selected the stained glass, and brushed in the details using a soft white brush at varying levels of opacity, depending where more aggressive or subdued blending was required.

The next step was a contrast boost.  I added a Levels adjustment layer, in which I marginally increased the blacks and marginally decreased the whites to add a global boost of contrast.

The next step was to apply some selective darkening, which I achieved by adding a new layer, changing the blend mode to ‘Soft Light’, and brushing in the desired darkness with a soft black brush at 20% opacity.  This is my usual technique for darkening, and sometimes I use multiple layers.

After darkening certain areas, I felt that the areas underneath the organ needed some subtle lightening.  I added the same type of layer as in the previous step, but used a white brush to lighten those areas.

The next step was to merge all of the previous layers, and add some Unsharp Mask to increase the contrast, as well as the Smart Sharpen filter for detail sharpening.

The final step was the blending the ‘Enhanced’ composite with the ‘Natural’ composite, on top of all of the above processing.

I added the ‘Enhanced’ composite to the ‘Natural’ composite as a new layer, added an inverted (ie, black) layer mask to hide the ‘Enhanced’ version, and then using a soft white brush at 50% opacity, I brushed the richer ‘Enhanced’ version onto the woodwork and side walls, leaving the ceiling and stained glass windows untouched.

And that concluded the processing of this image.

Let us look at another image, this time an exterior night shot, where I found that details from two different HDR composites together made for a better image.

I captured a twilight image of London‘s iconic Elizabeth Tower (colloquially, but incorrectly called Big BenBig Ben is actually the bell inside the tower) on our last night in London.

Like most of my images, I bracketed exposures, and decided to use HDR processing to bring out more detail than a single exposure would yield.  For this image, I used only three images, as twilight light is not so punishing as far as dynamic range is concerned.

Here is the result of the ‘Natural’ preset in Photomatix Pro:

Elizabeth Tower - HDR 'Natural' Preset

Elizabeth Tower – HDR ‘Natural’ Preset

In this HDR composite, there is lots of detail, and the detail in the clock face in particular can be clearly seen; however, the image looks flat, and the architecture of the tower itself looks very yellow and lacks again what I call ‘pop’.

I then decided to try another HDR merge, this time using Photomatix Pro’s ‘Creative’ preset.  This was the result:

Elizabeth Tower - HDR 'Creative' Preset

Elizabeth Tower – HDR ‘Creative’ Preset

I can mentally hear you exclaiming “Eeeeeewwww!”.  Yes, so did I.  In this case, the ‘Creative’ preset most certainly went over the top, and introduced some very displeasing and cringe-worthy artefacts.  There is too much contrast in the sky, there is a nasty halo around parts of the tower, and there is a lot of noise in the sky.

However, of interest to me in this image is the less garish appearance of the tower.  It contains loads of contrast, but is not such a flat, yellow expanse; and, most appealing of all, it contains the appearance of gold rather than the horrid yellow cast produced by sodium vapour lights.

It is just a little too much, though, so let us see what happens when we take the sky from the first HDR composite, and subtly blend the tower details from the second HDR composite.  Here is the result:

Elizabeth Tower - HDR 'Natural' and 'Creative' Presets Blended

Elizabeth Tower – HDR ‘Natural’ and ‘Creative’ Presets Blended

This is much more pleasing and realistic to my eyes.  The garish sky has been omitted, and the more metallic, golden, detail-rich architecture of the tower has been preserved.

For this blend of the two HDR composites, I used a brush at 50% opacity for the tower, but used 100% opacity for the clock faces.  The details in the clock faces in the ‘Enhanced’ HDR composite were just what I wanted, and the appearance is richer.

Unlike the cathedral image, the first layer I added was the HDR blend. I then did some other processing, but not as much as what I did to the cathedral image.

I cloned out some dust blobs and flare, added a Curves adjustment layer with the ‘Linear Contrast’ preset, darkened the sky, merged the layers and applied Unsharp Mask and Smart Sharpen for the final image.  Here is the result:

After 9pm on a Rainy London Night

After 9pm on a Rainy London Night

So, as can be seen by my images above, I have found a new way to produce richer HDR images using a combination of tone-mapping presets from Photomatix Pro, and restrained digital blending to take the best of both images for a stronger final result.

I hope that readers found value in this lengthy article, and also find inspiration to experiment with my new approach to HDR processing in their own photography.

Macro Experimentation: Focus Stacking

It has been a while since I shot a macro image.

Photo macrography is a form of photography which has traditionally frustrated me, because it is very challenging in terms of depth of field.

My past efforts have produced images where focus is very selective, and with a 180mm macro lens at minimum focus distance, it is hard to get very much of anything in focus, even when the aperture is stopped down considerably to increase depth of field without introducing diffraction.

For a while I have been pondering experimenting with focus stacking, a technique whereby one shoots a series of images with an identical composition and exposure level, but different points of focus; and then digitally ‘stacks’ the images in Photoshop to produce an image with a much greater depth of field.

Today I made my first attempt at focus stacking, and it was a success.  Here is the result:

Doing My Rounds

Doing My Rounds

I am looking forward to seeing what I can do with this technique when shooting a more interesting subject, but at least I have proven to myself that it can work very well.

A few important notes:

  1. Yes, this ammunition is real.
  2. Yes, I am licensed to possess and use this ammunition.

Calvin Hollywood’s “Freaky Detail”

A German photographer by the very cool name of Calvin Hollywood some time ago devised a Photoshop post-processing technique called “Freaky Detail”.

Hollywood’s technique intensifies local contrast and brings out details.  It is very handy when applied to subject matter such as rock shelves, timber jetties, or any other weathered, texture-laden surface whose details you wish to enhance.

Here is how to apply it:

  1. Stamp visible all layers (Opt-Cmnd-Shift-E) and rename the new layer to “Merged”.
  2. Duplicate the “Merged” layer (Cmnd-J) and rename the layer to “Freaky Detail Processing”.
  3. Change the blend mode of the “Freaky Detail Processing” layer to vivid light.
  4. Invert the “Freaky Detail Processing” layer (Cmnd-I).
  5. Apply surface blur (Filter -> Blur -> Surface Blur -> 40/40) to the “Freaky Detail Processing” layer.
  6. Stamp visible all layers (Opt-Cmnd-Shift-E) and rename the new layer to “Merged with Freaky Detail”.
  7. Change the blend mode of the “Merged with Freaky Detail” layer to soft light.
  8. Turn off visibility of initial “Freaky Detail Processing” layer.
  9. Add a layer mask to the “Merged with Freaky Detail” layer, invert the mask (Cmnd-I) and brush in the effect.

The above keystrokes are Mac-centric.  If you use a Windows machine, substitute Opt with Alt, and Cmnd with Ctrl.

The Making of “The Smoking Gun”

Almost five years ago to this date, an old Flickr contact of mine, Rich Legg, created a photographic image of a smoking gun.  I was impressed, and I commented on his image at the time.

I recently decided to have a go at this type of shot myself, and did so today.

Rich used a Glock 29, but I decided to use a real gun (sorry — gun humour).

Firstly, here is the image I produced this afternoon:

The Smoking Gun

The Smoking Gun

Now I will explain how I created it.

I vaguely knew how Rich went about creating his image, but I decided to take a slightly different approach.

While Rich did it in one shot, I decided in advance that the final image would be a composite of two images: one of the firearm, and another of the smoke.  I did not want to rig the set to capture both elements in one frame, and more critically, the lighting setups for each shot would be different, and would not work together.

The image of the firearm was shot with one lighting setup, and the image of the smoke was shot with a different lighting setup.

To photograph the firearm, I did the following (not in this particular order):

  • set up the firearm on a table, and angled it to point upwards at roughly 45 degrees;
  • placed a non-reflective black backdrop 90cm behind the firearm;
  • mounted a Canon Speedlite 580EX II on a light stand, positioned at 45 degrees camera left;
  • mounted a 42″ white translucent (shoot-through) umbrella on the stand;
  • configured the flash for half-power at 24mm zoom;
  • placed a white backdrop under the firearm to bounce light under the barrel assembly;
  • mounted my camera (with 135mm lens and remote shutter release) on a tripod, composed, focused and dialled in 1/160th at f/11 and ISO 100; and
  • attached PocketWizard PLUS II transceivers to both the camera and the flash.

With my remote shutter release in my left hand, using my right hand, I held my 80cm silver reflector to the right of the firearm, pointing upwards, to bounce light into the underside of the muzzle area.

To photograph the smoke, I used the same ‘set’, consisting of the black backdrop and the camera setup.  What changed most significantly was the lighting setup.

The smoke source was an incense stick I had bought.  I placed this in a glass bowl on the table where the pistol was positioned for the earlier shot, and lit it.

I placed the flash at 90 degrees to the right of the incense stick, about 10cm away, and elevated to the same height as the smoke.  On the flash, I dialled in 1/4th power and set the zoom to 80mm to concentrate the light to a narrower beam.

From that point it was simply a matter of snapping away, capturing various smoke formations wafting through the air.  I occasionally moved around, or waved my arm to agitate the smoke.

Shooting the smoke was the most challenging aspect, as smoke tends to be unpredictable, and it can take a while to score an aesthetically pleasing, well-composed shot of smoke, especially when it is to be used in Photoshop compositing as the smoke emanating from the muzzle of a gun.

After many shots, I landed one or two that were useful.  I settled on the second of the two candidates.

To create the final image, I performed raw conversion on both the firearm image and the smoke image.  I rotated the smoke image so that the smoke wafted upwards rather than at the angle at which it was moving at the point of capture.

I added the smoke image as a new layer in the firearm image, re-positioned it to align with the muzzle, added a black layer mask and painted the smoke into the image using a soft white brush at 100% opacity.

As anyone who has shot smoke can attest, smoke tends to appear blue.  To counter this issue, I added a desaturation adjustment layer, dialled down the saturation in the smoke so it appeared a more natural grey, and using a black layer mask, I painted the desaturation effect onto only the smoke.

Other minor adjustments included cloning, contrast and sharpness.

For those curious about the firearm, it is a Kimber Stainless Gold Match II, chambered in 9mm Parabellum.

In conclusion, a few important legal and safety-related notes:

  1. This firearm is real.
  2. This firearm is mine.
  3. I am licensed to possess and use handguns.
  4. It is not loaded.

I hope you enjoy both my image, and learning about how I created it.