As a recent convert to the Fuji system, I’ve definitely noticed that sharpening is one aspect of post processing that is surprisingly different from other camera systems. I’ve noticed many photographers that add slight sharpening in post having extreme artifacts in their images.
Luckily, I came across this post by Pete Bridgwood today. He talks about the differences between X-Trans and the typical Bayer array sensors uses in most digital cameras and how to account for them in post.
Sharpening Fuji X-Trans Files in Adobe Lightroom
Sharpening is one of the most taxing aspects of the digital process and consequently many photographers prefer to stick to safe and secure ways, either using presets, plug-ins, exporting to Photoshop or ultimately using JPEGs straight from camera. The X-Trans sensor produces wonderful JPEGs, and all the usual advice about always shooting in Raw doesn’t necessarily hold true anymore. There are now many professional photographers who happily shoot JPEG using X-Series cameras all the time and have no complaints.
JPEGs are very convenient, but for a landscape photographer like me, interested in the creative process and using post-processing as part of the digital alchemy, Raw files are so much more versatile. Sharpening Raw files from the X-Trans processor can be challenging for those of us who have grown familiar with more traditional Bayer array sensors; they demand a different approach and even experienced photographers will find there is a learning curve.
The sharpening controls in Adobe Lightroom have evolved to a degree of simplicity and perfection that eclipses much of the competition, including Photoshop. There were some initial teething troubles when sharpening X-trans files using earlier iterations of Lightroom; ‘waxing’ is one of the terms used to describe what can happen in images with high detail frequency (for example scenes with lots of fine detailed foliage). However, Adobe and Fujifilm have been working closely together to perfect the algorithms working behind the scenes. At the time of writing, I’m using Lightroom 5.6 to sharpen all my Fuji RAF files and creating exhibition prints up to A1 size without any significant problems.
This guide offers an introduction to perfect sharpening for Fujifilm X-Trans Raw files (.RAF files) in Lightroom 5
The processing of any digital image requires two essential and distinct types of sharpening: output sharpening and capture sharpening. Output sharpening is the final step in preparing an image for printing or display on screen. Because output sharpening always depends on known variables like printer model, paper type, and degree of enlargement, it is best performed automatically. In Lightroom, output sharpening is applied in the print module or for images intended for display on-screen it is applied on export. This guide relates only to sharpening that requires our human judgment, capture sharpening.
WHAT IS CAPTURE SHARPENING ?
The unprocessed digital image is an imperfect representation of reality due to the degradation of the projected image in various ways including separations between the micro-lenses overlying the light-wells on the sensor and, with conventional sensors, the blurring effects of the anti-alias filter. The purpose of capture sharpening is to correct for these flaws. When shooting JPEGs, the camera applies capture sharpening, but when shooting Raw images, no sharpening is applied. In Lightroom we apply capture sharpening by using the sharpening controls within the DETAIL panel of the DEVELOP module. The panel is appropriately named because sharpening works by looking for edges within the detail or micro-detail of the image; it accentuates some or all of them with relative degrees of intensity and spread according to the parameters we select. The amount of capture sharpening required varies depending on the camera, lens and aperture used and the characteristics of the individual image.
THE KEY TO SUCCESSFUL X-TRANS CAPTURE SHARPENING
I have found that the key difference between Raw files from conventional sensors and Raw files from X-Trans is that they favour different DETAIL slider settings: part of the sharpening control set within the DETAIL panel of the DEVELOP module.
Whereas conventional sensors usually favour a relatively low DETAIL slider setting and risk introduction of artefacts with very high detail settings, for X-Trans files, the reverse is true; they favour a high DETAIL slider setting and do not suffer anywhere near as much from introduction of artefacts. In fact, with X-Trans files, you’ll see more trouble from artefacts (albeit different ones) at lower detail settings. To anyone who has spent time processing conventional (Bayer array sensor) Raw files, this is completely counter-intuitive.
The DETAIL slider affects how Lightroom processes and emphasises fine details. It does this by changing the bias of which sharpening algorithms are being used. X-Trans files can take a lot of capture sharpening and they like a specific mathematical method known as ‘deconvolution’ sharpening. For my landscape work I find that most images work best with the DETAIL slider set all the way over to the right at 100; my understanding is that when the DETAIL is set to 100, Lightroom uses ‘deconvolution’ algorithms in preference.
CAPTURE SHARPENING WORKFLOW TIPS
1. Lightroom is designed with a top-to-bottom workflow in mind, because changing one parameter affects the settings required of others. For example, increasing the exposure of an underexposed image will increase the requirement for noise reduction. We should complete our adjustments in the BASIC panel before moving to the DETAIL panel for sharpening. Although a top-to-bottom workflow is most effective, moving back and forth from panel-to-panel and between controls within panels for iterative readjustment and fine tuning is the essence of a good Lightroom workflow.
2. Lightroom automatically applies a small amount of sharpening to all images by default, but this is seldom ideal for landscapes or X-Trans files. The ‘scenic’ sharpening preset is an improvement on the default settings, it can be found in the left-hand panel of the develop module under the Lightroom General Presets drop-down list. The ‘scenic’ preset offers a great starting point but it is a generic preset that disregards the camera and settings used; it is not at all ideal for X-Trans RAF files. The good news is, that you can create your own presets to better suit the characteristics of your camera.
My default landscape sharpening presets, providing good starting points for X-Trans RAF files from both the Fuji X-Pro1 and X-T1 are as follows:
X-Trans NORMAL : Amount 15, Radius 1.0, Detail 100, Masking 10.
X-Trans SHARP : Amount 25, Radius 1.0, Detail 100, Masking 10.
X-Trans SHARPER : Amount 35, Radius 1.0, Detail 100, Masking 10.
X-Trans TACK : Amount 45, Radius 1.0, Detail 100, Masking 10.
This particular naming convention ensures that when the settings are listed alphabetically, they are also listed in order of magnitude of sharpening applied from the least to the greatest.
3. We should magnify the whole image to 100% (or 1:1) before applying capture sharpening. The aim is to sharpen the image by an appropriate amount while keeping it looking natural. Throughout the process, repeatedly examine any areas of high contrast or edges and avoid the introduction of artefacts and haloes.
4. Holding down the OPTION / ALT key on the keyboard while moving any of the sliders switches to a black and white view, removing the distraction of colour contrast. This is essential when using the MASKING slider and useful when using the AMOUNT slider; it removes the distraction of colour contrasts and reveals the luminance channel on which the sharpening is actually performed.
5. The AMOUNT slider specifies the overall level of sharpening to be applied. Ask the question: are there any areas within the image that contain textural detail that needs sharpening? If the answer is yes, increase the AMOUNT until those areas start to look ‘crunchy’, then pull back a little. Images made using the best lenses on cameras with high resolution sensors can take more sharpening before developing haloes and artefacts.
6. The RADIUS slider determines the spread of the sharpening effect on either side of edges, it is an approximation of the number of pixels over which the sharpening is applied, while a high value accentuates sharpening, it also causes unwanted haloes. Increases in both AMOUNT and DETAIL will accentuate the effect of the RADIUS setting. For landscape images I find values as low as 0.6 or 0.7 can work well, but portrait photographers will often favour values above 1.0 and use correspondingly lower values for AMOUNT and DETAIL. I have found with my X-Trans files that setting RADIUS to 1.0 works well with such high DETAIL settings. Use lower RADIUS settings for high resolution images containing fine textural detail, but be wary of introducing artefacts and haloes.
7. While AMOUNT and RADIUS control the degree of sharpening, the DETAIL slider determines how the sharpening is performed by changing the individual bias of various mathematical algorithms used to sharpen the image. Conventional wisdom suggests that small values are more suited to ‘low-frequency’ less detailed images. High values are more useful for ‘high-frequency’ images with fine textural details. For practical purposes, we can think of the detail slider as controlling the emphasis of fine detail. The AMOUNT and DETAIL sliders both accentuate sharpening and increase noise, an increase in one parameter often requires a decrease in the other and an increase in either setting might lead to a requirement for noise reduction using the LUMINANCE slider.
8. All the above sliders apply sharpening globally, but our ultimate objective is often to only sharpen certain elements. The MASKING slider allows us to ‘turn-off’ sharpening in the solid or smooth toned areas of the image to remove the distraction of unwanted artefacts or noise. In landscapes, this most commonly applies to skies. With MASKING set to zero and OPTION / ALT held down, the whole image starts off white, indicating that sharpening will be applied to the whole image. As we increase MASKING from zero, any areas that become black will not be sharpened at all and any areas that remain white will be.
9. Should MASKING not allow the control required to eliminate sharpening in a particular area of the image, then we can use an ADJUSTMENT BRUSH with a setting of -50 to make local changes and completely remove any sharpening globally applied by the DETAIL panel, regardless of the AMOUNT. Setting the brush sharpness to less than -50 will actively blur the image and using a positive setting will enhance sharpening locally, this is known as ‘creative sharpening’.
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