Clarity, sharpness, and crispness are three terms that are frequently used to express the properties of a good photo. While there is probably no rigorous definition for these terms (except for sharpness, maybe) we all know what they mean, and we all strive to give these properties to our images. But what exactly does that mean? How can you make an image look sharp, crisp, and clear? In this post, I am going to explain the principle method for achieving this in post-processing. As you will quickly see, there is no secret here, no magic and no dark forces are involved. Making an image look clear, sharp and, crisp is just a matter of understanding the image, knowing your tools, and some labor.
Assumptions and Requirements
Note that this is not a recipe for rescuing blurred and unsharp images. I assume that you have (at least reasonably) sharp images to start with. If your source images are really blurry, there is really nothing you can do except for making new source images. I assume that you have created a tone-mapped image and that you did your utmost to reduce any blur in the image (reducing CA, deghosting etc). The procedure you used for merging the source images, the tone-mapping operator you used, and the number of source images you used does not really matter here.
What does Clarity actually Mean?
For simplicity, we will subsume our three terms under the term clarity. What does clarity actually mean? I will explain this based on an example:
In Figure 1, you see two versions of the same image. Most people would say that the right one has more clarity than the left one. Why is that and what does this mean?
In Figure 2, the key elements of the image are marked. They comprise
- the marble walls
- the wooden floor
- the rich ornaments at the top of the walls
- the chandeliers
- the ceiling
- the vases to the left and right of the door, and
- the chairs that are arranged around the room.
The reason for the increased clarity in the right images in Figure 1 is the following: These key elements of the image are more clearly separated from each other and the contrast between the elements was increased by processing them separately.
Note that by contrast I do not necessarily refer to the tonal range as it can be adjusted e.g. using a levels adjustment layer in Photoshop. Contrast also includes color contrasts or the contrast between an area with high saturation and one with little saturation. E.g. note how the ornaments on the walls (3) and the vases (6) have a much larger contrast to the walls at the right side of Figure 1 than on the left side. This fact separates them from the rest of the image and makes the image appear more clear and also sharper. In the left image, all elements appear to have a slight orange cast making them appear similar and not easy to differentiate. Therefore, it appears as if you see the left image through orange sunglasses. In the right image, each element has its own color characteristics: The walls appear to be made of pure gray marble, the ceiling has nice blue tones, and the golden parts of the chandeliers come out nicely.
This separation is extremely hard to produce with normal global images adjustments. For example, any global adjustment that reduced the orange cast of the walls also reduces the saturation of the floor and the ornaments.
As you have seen in the example, clarity ia all about separating the key elements of the image more clearly from each other. This requires three essential things:
- You have to identify the key elements in your images. You do this before you start the post-processing by having a close look at the image and by making a deliberate decision about what you consider as the key elements.
- You have to process the elements of the image separately. Until now, your post-processing work may have been limited to applying some global adjustments to the entire image. This is not sufficient for what we are trying to achieve here. You will have to work on the different elements of your images separately. This requires working with layers and creating masks.
- Patience and hard labor. Creating masks in order to be able to work on the elements of your image separately is the most time-consuming task in this entire process. Just as a ballpark number, I am spending around 70-80% of my post-processing time on creating masks.
Identifying the key elements of your image
Identifying the key elements of your image is a vital part of the creative process. There are no strict rules for this, but once you have analyzed a few images, you will quickly understand this process. I will give you a couple of examples:
Figure 3 shows the tone-mapped image of the Brandenburg gate in Berlin against the sunset. On the right side, you see the key elements I identified here.
In the post-processing of this image, I was trying to enhance the color contrast between the sky and the gate in this image. My idea was to enhance the blue tones of the sky while enhancing the yellow/orange colors in the gate. This is a classical color contrast that can add an interesting aspect to an image. Doing both adjustments with a single global adjustment is not possible. The ground, on the other hand, should retain its natural color without getting too orange or too blue. Hence, the ground was the third key element in this case. Here is the final image:
The second example is shown in Figure 4. Again, I was going for an enhancement of the color contrasts. I wanted to enhance the blues in the sky and at the same time keep the clouds free of any color cast with a nice white and contrast-rich appearance. Thus, the clouds were one key element here.Â The red, yellow and orange tones in the middle part would make a nice contrast to the blue and green tones in the water. Hence, the mountains, the boats, and the dock were the second element. The water was an obvious choice for the third element. I wanted to enhance the red, yellow, and orange tones of the dock and the blue and green tones of the water by keeping a nice clean white in the board wall of the dock and in the ships in the background. Therefore, these element made up the final key element in this image.
Here is the final image after all the post-processing:
Masking the Key Elements
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After you have identified the elements that you want to work on separately, the labor starts. It is best to create a group for each of the elements. Inside this group, you can create all the adjustments layers for the element. The group itself will be equipped with a layer mask that only reveals the element and masks everything else. Hence, the main tasks are:
- Creating groups: I have covered the essentials of groups and how to equip them with layer masks in my recipe on Structuring a Project.
- Creating masks: Masks can be created by making a selection in the image and then clicking the “Add layer mask” button as explained here. The difficult part is really to make the selection. Read my recipe on Complex Selections for an overview on the different methods for doing this.
Here are a few tips for your work on layer masks:
- For delicate details, you will be using the Brush tool to work directly on the layer mask (see Complex Selections). I highly recommend that you buy a graphics tablet for this work. This work is very difficult with a mouse. You do not need an expensive graphics tablet, but you need one.
- Make sure you work with precision. Using layer masks to work on different parts of the image can considerably increase the perceived sharpness of an image at the borders of a mask: The areas on both sides of such a border will be processed differently which creates a stronger contrast at this edge. Of course this is only true if your mask is precise.
- If you are using a brush, make sure that the hardness is low. A low hardness means that the edges of every stroke are smooth and soft. This creates a more natural look by avoiding harsh transitions in the image.
- Learn how to combine masks: A mask can easily be turned into a selection by holding the Ctrl key down and making a left-click on the mask. Furthermore, if you right-click on a mask, a pop-up menu opens that lets you add, subtract, or intersect the mask with the current selection. This is an easy way of combining masks which comes in handy in some situations.
- When you are masking fine details with a brush, be prepared to zoom into the image – sometimes as much as 300%. Sometimes you will need a brush that is only a few pixels wide.
- Before you do any masking work, create the group and the adjustment layers and configure those adjustment layers to preview the effect. The effect will apply the whole image since there is no mask yet. But it lets you judge whether it looks as you intended. The fine-tuning will be done later when the mask is complete. After you have all the adjustment layers in the group, create a new black layer mask (see here and here for details) – if the brush is your choice for creating the mask. Then, start using your brush on the layer mask while you display the image. This means that you are brushing the effect of the adjustment layers right onto the image such that you can verify the effect directly.
Processing the Key Elements
Masking is the labor part but the actual processing of the elements is where the clarity is really gained. The basic goal in his process is to work on the contrasts between the different elements. The trick is to enhance these contrasts without overdoing it. For example, if you desaturate one part of the image, do not completely desaturate it as this would make your adjustments apparent and the effect would look artificial. Of course, this is subject to your taste, and people have completely different opinions on this.
You can work with saturation, levels, curves and even with photo filter layers. The latter would be used to introduce a more radical change in the color of some elements. For example, an orange photo filter layer was used on the vases in the images shown in Figures 1 and 2. The basic idea is that you create those adjustment layer inside the element’s group and work on the effect you are trying to achieve by fine-tuning the adjustments.
A Word of Caution
There are different schools of thought out there when it comes to the realism of a photo. As you are interested in HDR, you may have come across a number of discussions were people fight violently over the question as to whether HDR has to be used for creating a realistic impression that is as close to what the eye has seen or as to whether it is permissible to use the technology to create artistic images that may, in some cases, be far away from the original scene. You should be aware that the basic philosophy of creating clarity may violate the idea of realistic-looking images. As always, you may use the techniques introduced here either way.